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What Are FFPE Curls?

Researcher analyzing FFPE curl under microscope

What Are FFPE Curls?

Formalin-fixed paraffin-embedded (FFPE) curls play a crucial role in the rapidly advancing world of histology and pathology. FFPE tissue curls refer to the small sections of biological tissue that have undergone a preservation and embedding process, making them invaluable for research and diagnostic purposes. Keep reading to delve into the significance of FFPE curls, their preparations, and their applications in scientific and medical research.

Researcher analyzing FFPE curl under microscope

Understanding FFPE Curls

FFPE curls are thin, curled shavings of tissue that are meticulously prepared for microscopic examination and analysis. The process begins with tissue samples, which are preserved using formalin (a solution of formaldehyde in water). This crucial fixation halts biological processes, preserving the tissue’s cellular architecture and preventing decay. Following fixation, the tissue is embedded in paraffin wax, a process that stabilizes the sample for long-term storage and facilitates thin sectioning. 

5 Essential Steps to Prepare FFPE Tissue Curls

The journey from tissue to FFPE curls involves several meticulous steps: 

1. Tissue Fixation:

The fresh tissue sample is immersed in formalin, which cross-links proteins and nucleic acids, effectively preserving the sample at a molecular level. This process usually takes between 6 and 48 hours, depending on the tissue size and type. 

2. Dehydration: 

After that, a series of alcohol baths are used to eliminate any last traces of moisture from the fixed tissue. Dehydration is essential because paraffin and water do not mix.

3. Clearing:

After dehydration, the tissue is treated with xylene or a similar solvent, which makes the tissue transparent and prepares it for infiltration with paraffin. 

4. Embedding:

The cleared tissue is then infiltrated with melted paraffin wax. Once thoroughly filled, the tissue is placed in a mold with more paraffin and allowed to harden, forming a solid block.

5. Sectioning:

Using a microtome, the paraffin-embedded tissue block is sliced into ultra-thin sections, typically 4–5 micrometers thick. These thin sections, known as FFPE tissue curls, are collected and placed onto glass slides for staining and microscopic examination.

The Importance of FFPE Curls

FFPE curls provide unmatched insight into the mysteries of biomedical research. Through an exact procedure, researchers are able to preserve samples in a way that prevents degradation and decay. FFPE curls have proven to be extremely useful in various fields, including:

Diagnostic Application

FFPE tissue curls are a cornerstone of pathology. They allow pathologists to examine the microscopic structure of tissues, aiding in the diagnosis of various diseases, including various cancers, genetic disorders, and congenital disabilities. By analyzing these curls, pathologists can identify abnormal cell morphology, tissue architecture, and other histological features indicative of disease. 

Research and Development

Beyond diagnostics, FFPE curls are invaluable in medical research. Researchers use samples to study disease mechanisms, identify biomarkers, and develop new treatments. The preservation of genetic materials in FFPE tissue allows for molecular analyses, such as DNA and RNA sequencing, which are critical for understanding genetic mutations and their roles in disease. 

Advantages of Using FFPE Tissue Curls

Since their introduction decades ago, FFPE tissue samples have provided researchers and medical professionals with important information that helps them treat complex diseases like cancers. Thanks to these special samples, FFPE samples can be studied without being harmed in a way that prevents further research. 

Long-Term Preservation

One significant advantage of FFPE tissue curls is their longevity. Properly prepared FFPE samples can be stored for decades without significant degradation. This long-term preservation is particularly beneficial for retrospective studies, where researchers can analyze historical tissue samples to gain insights into disease progression and treatment outcomes over time. 

Wide Availability

FFPE tissue curls are widely available in pathology labs and biorepositories worldwide. This widespread availability facilitates large-scale studies and collaborative research efforts, enabling scientists to share and compare data across different populations and regions. 

Compatibility with Advanced Techniques

Modern molecular biology techniques, such as PCR (Polymerase Chain Reaction) and next-generation sequencing (NGS), are compatible with FFPE tissue curls. This compatibility allows researchers to extract and analyze genetic material from preserved tissues, opening new avenues for genetic and genomic studies.

Challenges and Considerations

Though the benefits of FFPE curls are overwhelming, the challenges involved with correctly preserving delicate tissues can mean the difference between a successful preparation and a tissue that will yield inaccurate results. Consider the following factors when selecting a reputable biobank provider: 

Quality Control

Despite their advantages, the preparation of FFPE tissue curls requires meticulous attention to detail. Variations in fixation time, dehydration, cleaning, and embedding can affect the quality of the final sample. Therefore, standardized protocols and rigorous quality control measures are essential to ensure the reliability and reproducibility of results. 

Degradation of Nucleic Acids

While FFPE preservation maintains the structural integrity of tissues, it can sometimes lead to fragmentation of nucleic acids. This degradation poses a challenge for molecular analyses, particularly when studying dated or poorly preserved samples. Advances in extraction and amplification techniques are continually improving the ability to work with degraded nucleic acids from FFPE curls.

Future Perspectives of FFPE Curls

FFPE tissue curls are merely a stepping stone in the journey to biomedical understanding of disease and health. Examining FFPE samples has led to various discoveries for researchers, but with proper sample preservation, FFPE samples have a special potential to advance future medical research as well. FFPE curls have a wide range of potential future applications, which include: 

Technological Advancements

The field of histology and pathology is continually evolving, with new technologies and methods enhancing the utilization of FFPE tissue curls. Digital pathology, for instance, is revolutionizing the way tissue samples are analyzed and shared. High-resolution digital scanning allows for the creation of virtual slides(digitally scanning physical FFPE slides to share them from anywhere in the world), enabling pathologists and researchers to examine FFPE tissue curls remotely and collaborate more effectively.

Personalized Medicine

The integration of FFPE tissue analysis with genomic and proteomic data is paving the way for personalized medicine. By understanding the molecular and genetic underpinnings of diseases, clinicians can tailor treatments to individualize patients, improving outcomes and minimizing adverse effects.

Order Top-Quality FFPE Curls from Superior BioDoagnostics

FFPE curls are vital in biomedical research. The delicate process of preparing FFPE tissue samples, if performed properly, can provide answers to longstanding medical mysteries. The advantages of using FFPE tissue curls, such as long-term preservation, wide availability, and compatibility with advanced techniques, make these thin samples hold a major significance in pathology medical research. Order from a top biobank provider like Superior BioDx for only the best human FFPE tissue curls.

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PCR Using DNA From FFPE Tissue Samples

Researcher holding PCR tube to put into PCR machine

PCR Using DNA From FFPE Tissue Samples: A How-To Guide

Polymerase Chain Reaction (PCR) is a widely accepted technique used in molecular biology, aiding researchers in amplifying and analyzing specific DNA sequences with heightened accuracy. However, when DNA is extracted from Formalin-Fixed, Paraffin-Embedded (FFPE) samples, you’ll face unique challenges due to DNA fragmentation and chemical modifications introduced during the preservation process. 

In this complete how-to guide, we walk you through how to perform PCR on FFPE-derived DNA. We share helpful tips and best practices, ensuring your PCR testing is accurate and efficient. Whether you’re an experienced researcher or utterly new to this field, our guide will give you the knowledge and expertise to achieve reliable results in your PCR analyses. Keep reading if you’d like to learn how to conduct PCR techniques on DNA collected from FFPE tissue samples!

Researcher holding PCR tube to put into PCR machine

What Are FFPE Tissue Samples?

Formalin-fixed paraffin-embedded (FFPE) tissue samples are essential to scientific and medical research. FFPE is a preservation technique that aids in maintaining the cellular and tissue structure of biospecimens, preparing them for various purposes, including cancer research, genetic studies, immunohistochemistry (IHC), translational clinical research, and more. 

FFPE tissue samples are fixed in formalin, embedded in paraffin wax, and stored in biobanks, laboratories, or hospitals. After the preservation process, these samples can be used for decades. 

The Basics of PCR

Polymerase Chain Reaction (PCR) is a widely used technique in which short sections of DNA or RNA are amplified into multiple copies using primer-mediated enzymes. PCR allows researchers to make billions of copies of a specified DNA gene or fragment, permitting the investigation and identification of gene sequences using visual tactics based on charge and size.

polymerase chain reaction

There are 3 primary steps involved in PCR: denaturation, annealing, and extension. Outlined below is what happens during the amplification process: 

  1. Denaturation: Denaturation involves heating the selected double-stranded DNA sample to about 94℃ for 0.5–2 minutes. This temperature breaks down the hydrogen bonds between both strands of DNA, converting them into a single strand. Researchers will use this single-stranded DNA as a template for producing new strands. If necessary, the high temperature must be applied for an extended period to ensure the separation of the two strands. 
  2. Annealing: Next, researchers will lower the temperature to 54–56℃ for about 20–40 seconds. During this time, the primers will anneal or stick to their complementary regions on the template DNA. Primers are sections of single-stranded RNA or DNA around 20–30 bases in length. Lowering the temperature allows hydrogen bonds to form between the template DNA and primers in areas where the section corresponds. Both separated strands of DNA run in opposite directions with two primers: a forward and a reverse primer. 
  3. Extension/Polymerization: During extension, the temperature is again raised to 72–80℃. Then, the DNA polymerases are added to the 3’ end of each primer. These enzymes move along the DNA base by base in the 5’ to 3’ direction, adding the matching DNA nucleotides as it goes. The DNA polymerase often adds about 100bp/minute under pristine conditions. As the polymerase attaches to the primer, it adds DNA bases to the single strand, resulting in a double-stranded DNA molecule. 

Denaturation, annealing, and extension are usually repeated 20–40 times to obtain the necessary number of DNA sequences of interest quickly. PCR testing contributes to diagnosing infectious diseases, monitoring the gene in gene therapy, genetic fingerprinting and paternity tests in forensic science, finding small amounts of cancer cells that could be overlooked in other studies, and more.

Can You Do PCR On DNA From Formalin-Fixed Paraffin-Embedded Tissue? Yes, Here Are 5 Steps You Can Follow

If you’d like to try PCR testing on DNA extracted from FFPE tissue samples, here are 5 simple steps you can follow:

Prepare the FFPE Tissue Samples for DNA Extraction

You’ll need to use a microtome to cut the exposed FFPE tissue samples into thin sections (5–10 micrometers). A microtome slices specimens continuously, creating a “ribbon” of tissue sections that can be used for DNA extraction. After cutting, you can place the FFPE tissue sections in microcentrifuge tubes. Then, the FFPE tissue samples need to be deparaffinized. Remove the paraffin using a series of xylene washes and ethanol rinses to rehydrate the biospecimens. 

Extract DNA and Run a Quality Assessment

After preparing the FFPE tissue samples, it’s time to treat the deparaffinized specimens with proteinase K. This enzyme allows the specimens to break down a wide range of proteins and release DNA. The use of proteinase K in DNA extraction reduces the risk of false negatives or various errors that can arise in diagnostic studies. 

Incubate the DNA and proteinase K mixture at 55–65℃ for several hours or overnight, ensuring the protein contaminants are removed from the DNA samples before the PCR process. This will increase the likelihood of reliable results. Following incubation, use a DNA extraction kit (specialized for FFPE samples) or phenol-chloroform extraction to purify the DNA.

It’s essential to quantify the DNA concentration at this time. A spectrophotometer (e.g., Nanodrop) or fluorometer (e.g., Qubit) is used to measure the DNA concentration. Additionally, ensure the quality of the DNA by running a small section on an agarose gel. The FFPE DNA is commonly fragmented, which is normal. 

Optimize and Prepare PCR Setup

Before performing PCR testing, you need to prepare the setup and ensure quality at every step. Here are 3 best practices for optimizing your PCR process:

    1. Practice Expert Primer Design: Due to the formalin fixation process, FFPE specimens often contain highly fragmented DNA. In this case, design a primer that amplifies short DNA sections (100–300 base pairs). Professional primer design technology (e.g., Primer3, NCBI Primer-BLAST) should be used to make certain the primers are customized to the specified sequence instead of forming secondary structures or primer dimers.
    2. Invest in High-Quality PCR Reagents: We recommend using a high-fidelity DNA polymerase, precisely one that’s compatible with complex templates. These polymerases are increasingly tolerable to the inhibitors often appearing in FFPE-derived DNA. For your PCR buffers, use ones that are provided with high-fidelity DNA polymerases since they’re ideal for challenging templates. 
    3. Include Additives: PCR additives or enhancers can improve the overall amplification efficiency. Consider adding bovine serum albumin (BSA) or dimethyl sulfoxide (DMSO) to stabilize the polymerase and improve the PCR process on difficult DNA templates. Other additives, including betaine or formamide, can also reduce the chance of secondary structures. 

After gathering your supplies, it’s time to prepare the PCR setup. Assemble the PCR reaction mixture, including the primers, template DNA, deoxynucleotide triphosphates (dNTPs), buffer, polymerase, and any chosen additives. Then, consider the ideal PCR cycling conditions for your process, which involve denaturation, annealing temperature, extension time, and the number of cycles. 

Perform the PCR Amplifation Process

Using a thermal cycler, you’ll then perform the PCR process on the FFPE-derived DNA. As we’ve mentioned prior, there are 3 steps involved in amplification: denaturation, annealing, and extension. If you’re new to trying PCR, doing a temperature gradient during the process is helpful. Here are the standard cycle conditions for PCR you can start with according to University of Nebraska’s Herman Lab:

Conditions

Guidelines

Denaturation

Temp: 95℃. Time: 2 minutes on initial cycle; 30 seconds to 1 minute on rest.

Annealing

Temp: 5℃ below Tm (melting temperature) of the primers; no lower than 40℃. Time: 30–45 seconds. This is the step where you’d use a gradient.

Extension

Temp: 72℃. Time: ~1 min/kb of the expected product; 5–10 minutes on the last cycle.

Number of Cycles

~30 cycles

Analyze the PCR Products

Once you’ve finished the amplification testing, analyzing the PCR products is crucial to ensure the process is successful. Use agarose gel electrophoresis to determine effective amplification and correct amplicon size. If needed, you can purify the PCR products by utilizing a PCR cleanup kit for purposes such as sequencing or cloning.

Obtain FFPE Tissue Samples for Your PCR Analysis

Are you in need of high-quality FFPE tissue samples for PCR testing? Superior BioDiagnostics has a biorepository containing thousands of pristine FFPE tissue samples that are available for your research purposes. Our biobank specializes in normal, malignant, and disease-state FFPE specimens collected from various anatomical sites, including but not limited to breast, cervical, lung, muscle, and uterus samples. Contact Superior BioDiagnostics today to order FFPE tissue samples and ensure accuracy in your PCR analysis.

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What is H and E Staining? A Complete Guide

Storage rack of tissue sections on slide glasses used for H&E staining

What is H and E Staining? A Complete Guide

Microscopic tissue analyses are essential in the fields of medicine and medical research. Staining techniques are frequently employed to enhance the visibility of cellular structures and enable differentiation between various tissue components. One of the most popular and effective methods currently in use is the H and E stain method. Keep reading to explore the complexities of H&E stains, the technique’s significance, and its applications.

Storage rack of tissue sections on slide glasses used for H&E staining

H&E Stains: A Closer Look

H&E staining, short for Hematoxylin and Eosin staining, is a histological technique for visualizing cellular structures under a microscope. It provides vital information about tissue composition, cellular morphology, and pathological changes. Named after the dyes used in the process—hematoxylin and eosin—H&E stains allow easier identification and detailed analysis by dying specific tissue components with distinct colors.

How to Prepare Human Tissue for H and E Stain

The process of H&E staining involves several procedural steps, each crucial for achieving optimal results. Before a sample can undergo staining, it is prepared using methods that allow for long-term storage and examinations. 

The tissue specimen, obtained through biopsy or surgical excision, is first set in a fixative solution to preserve its structure and prevent degradation. The most common fixative method is called formalin-fixed paraffin-embedded (FFPE) tissue samples. This preservation method involves dehydrating the tissue with an increasingly concentrated drying agent, formalin, which removes water molecules from the tissue, preparing it for infiltration with paraffin. The embedding process supports the tissue and allows for thin sectioning. A microtome is used to create thin sections of the embedded tissue, usually 4-5 micrometers thick. These sections are then mounted onto glass slides for staining. 

Now that the sample is preserved, a section will need to be deparaffinized before it can accept staining agents. Deparaffinization is achieved by immersing the slides in a series of xylene, a volatile liquid created by distilling wood, coal, tar, or petroleum. Xylene is a solvent that will dissolve the paraffin. Next, the sample is rehydrated through an alcohol regimen with decreasing intensity. Finally, the sample is ready for staining.

How To Apply H&E Stains in 4 Steps

  1. Hematoxylin Staining: The tissue sections are immersed in a hematoxylin solution, a basic dye derived from the logwood tree. Hematoxylin selectively stains acidic structures (such as nuclei), imparting a blue-purple color. 
  2. Differentiation: After hematoxylin staining, the slides are rinsed with water or acidic alcohol, removing excess dye. This step is easy, but it is very important because it helps achieve the best contrast and definition of cellular nuclei.
  3. Eosin Staining: The tissue sections are then counterstained with eosin, an acidic dye that stains basic structures such as cytoplasm and extracellular matrix, turning a pinkish-red color.
  4. Dehydration and Mounting: Following H&E stains, the slide is dehydrated in alcohol solutions, flushed in xylene, and mounted with a coverslip using a mounting medium.

Once staining is complete, researchers are able to view structures like nuclei distinctly as a cool, blueish-purple color, clearly separated from cytoplasms and extracellular matrix, which are now dyed bright red.

Applications of H&E Stains

H&E staining finds widespread applications across various fields, including histopathology, biomedical research, and furthering medical education. In medical diagnostics, H&E staining is indispensable for examining tissue specimens to identify pathological changes indicative of diseases such as cancer, inflammation, and infection. The staining pattern and cellular morphology observed under the microscope aid pathologists in making accurate diagnoses.

H&E staining is a fundamental tool in biological research because it allows scientists to study tissue structure, cellular organization, and structural alterations in experimental models. It provides valuable insights into the underlying mechanisms of diseases and the efficacy of potential medical interventions. H&E stains are highly regarded by top biomedical professionals and researchers. The technique is integral to the histology curriculum in medical and life sciences education across the globe. Students learn to interpret tissue sections and recognize normal and abnormal histological features, laying the foundation for understanding disease processes and further discoveries.

Advantages and Limitations of H&E Stains

H&E staining offers several advantages, including simplicity, versatility, and ease of interpretation. The H&E staining protocol is relatively simple and cost-effective, making it accessible to laboratories large and small. H&E staining is incredibly versatile and can be applied to a wide range of tissue types and species, making it suitable for diverse research and diagnostic purposes. The distinct color contrast imparted by H&E staining facilitates easy interpretation of tissue morphology and cellular architecture under the microscope. 

However, H&E staining also has certain limitations, such as interpretive subjectivity, the introduction of unwanted artifacts, and insufficient specificity in research results. Interpreting H&E-stained slides may be subjective and require expertise and experience, particularly in distinguishing subtle biological changes. Additionally, any variations in tissue processing and staining techniques can introduce artifacts, potentially affecting the accuracy of histological assessment. While H&E stains provide an overview of tissue structure, they may not always offer sufficient specificity for certain pathological conditions, necessitating additional ancillary tests. 

H&E staining, with its ability to reveal intricate details of tissue architecture and cellular morphology, remains a cornerstone of histological analysis in both clinical and research settings. By employing a simple yet powerful staining technique, researchers and pathologists can gain invaluable insights into the complex world of biological tissues, paving the way for advancements in diagnosis, treatment, and understanding of human health and disease. 

Quality FFPE samples for H&E Stains by Superior BioDiagnostics

Order your professional-quality FFPE human tissue samples for H&E staining from Superior BioDiagnostics today and discover the genetic secrets of tomorrow. Explore our inventory of normal and malignant samples of varying tissue types, including breast, cervical, muscle, lung, and more. Contact Superior BioDx to order your samples today. 

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DNA and RNA Extraction from FFPE Tissue

Diagram showing DNA molecules

DNA and RNA Extraction from FFPE Tissue

Biomedical research frequently involves long-term studies, making tissue sample preservation essential for further advancements. Formalin-fixed paraffin-embedded (FFPE) tissue is a widely used preservation technique that continues to provide groundbreaking biological insights. This preservation method maintains the tissues’ integrity over an extended length of time and allows for the extraction of multiple sections from a single block. However, researchers face particular complexities when attempting to extract genetic material from FFPE samples. Continue reading to discover the process and understand the special care taken in order to isolate RNA and DNA samples without damaging the material in the process.

Diagram showing DNA molecules

FFPE DNA Extraction, A Slice of Innovative Biomedical Research

FFPE DNA extraction is a sensitive procedure and a trusted practice that holds immense significance in various fields, including cancer research, genetic studies, and forensic investigations. These archived tissue samples offer valuable insights into disease progression, biomarker discovery, and therapeutic plans. The FFPE preservation method was established in the late 1800s, and according to SageJournal’s Journal of Histochemistry & Cytochemistry, DNA extraction from FFPE samples began in the late 1900s. Since then, researchers have taken calculated action to optimize extraction protocols to obtain high-quality genetic material from FFPE samples. The practice has become essential in advancing biomedical research and clinical diagnostics.

Once the genetic material is extracted from the FFPE section, researchers are faced with multiple hurdles to preserve the sample before it succumbs to deterioration. Formalin-induced cross-links and RNase (äreˈnās), enzymes that break down RNA into smaller molecules, exacerbate the molecule’s inherent instability and susceptibility to degradation. To overcome such obstacles, RNA extraction protocols for FFPE samples incorporate methods to reverse cross-links, mitigate RNase activity, and preserve sample integrity.

Overcoming The Challenges of FFPE DNA Extraction

Traditional DNA extraction methods often fail to efficiently recover intact DNA stored for long-term use in FFPE samples without damaging the strands. However, specialized protocols tailored to FFPE tissue have proven to promote the longevity of extracted samples. Heat-induced antigen retrieval is a common pre-treatment step that involves incubating the FFPE tissue sections to maintain their integrity and reverse formalin-induced cross-links.

After incubation, the nucleic acids have been exposed, but the presence of enzymes like RNase often prohibits extraction at this point. Utilize proteases, enzymes that break the peptide bonds of proteins, or proteinase K, to remove any remaining enzymes that could damage your sample. This enzymatic digestion helps break down proteins and release DNA from the cross-linked matrix. If any remaining enzymes are present, samples are oftentimes bound to silica-based columns; fragments of the sample can be isolated using magnetic beads, reducing damage while residual contaminants are removed to complete the process.

Advancements in FFPE RNA Extraction Techniques

Advancements in FFPE RNA extraction techniques have significantly improved the efficiency and reliability of isolating high-quality RNA from archived tissue samples. These advancements address the challenges posed by formalin fixation and degradation, allowing researchers to unlock valuable genetic information stored within FFPE specimens. One notable advancement is the development of specialized extraction kits tailored specifically for FFPE samples. These kits often incorporate innovative reagents and protocols designed to optimize RNA recovery while minimizing sample breakdown.

4 Steps For Successful FFPE RNA Isolation

In addition to the specialized extraction protocols that have revolutionized FFPE RNA isolation, several key considerations must be addressed to ensure optimal results.

  • Sample Quality: The quality of an FFPE RNA isolation often reflects the quality of the original FFPE sample. Assess FFPE sample quality, including tissue fixation duration and storage condition. This crucial step could determine your extraction success. By ordering from a reputable biobank, you can trust the quality of your samples and set your research up for success.
  • Pre-treatment: Tailor pre-treatment steps, such as antigen retrieval and enzymatic digestion, based on sample characteristics to enhance nucleic acid recovery. Different sample characteristics, such as tissue type, age, and preservation method, can affect nucleic acid recovery. For example, heterogeneous samples, like tumors, often need customized protocols to ensure a representative analysis. 
  • RNase Barrier: Incorporate RNase inhibitors throughout the extraction process to safeguard RNA integrity and prevent decay.
  • Quality Control: Implement rigorous quality control measures, such as spectrophotometric analysis–to determine the concentration of DNA and RNA molecules–and PCR-based assays–to determine the presence of pathogens. These tests can be used to validate the integrity, purity, and success of the FFPE RNA isolation.

 

Unlock the Biomedical Secrets of FFPE Tissue Samples with Superior BioDiagnostics

DNA and RNA extracted from FFPE tissue offer a vital gateway to uncovering the genetic mysteries concealed within archived samples. The recovery of high-quality genetic material from FFPE samples has been transformed by creative extraction techniques despite the difficulties presented by formalin fixation. By adopting specialized methods, researchers will overcome challenges, enable the leverage of the abundant data in FFPE tissue, and propel progress in biomedical research and clinical practice.

Order your FFPE human tissue samples directly from Superior BioDiagnostics to pave the way for transformative discoveries and shape the future of medicine and molecular biology. Contact Superior BioDx–the biobank of choice for top-rated academic institutions–today and launch your research to the future with top-quality FFPE human samples. 

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FFPE Blocks, Slides, & Sections: Definitions & Use Cases

A tray on lab table carrying ffpe blocks, slides, and sections

FFPE Blocks, Slides, & Sections: Definitions & Use Cases

Formalin-fixed paraffin-embedded (FFPE) tissue samples are vital in pathology and biomedical research. This preservation method was established in the late 1800s and has brought incredible understanding to biomedical researchers. Now, FFPE samples provide a long-lasting preserved archive of samples for repeated examinations. Keep reading to learn the stages of a sample collected for FFPE preservation and explore the diverse uses of FFPE tissue samples across different disciplines.

A tray on lab table carrying ffpe blocks, slides, and sections

What Are FFPE Tissue Blocks, Slides & Sections?

FFPE Tissue Blocks

Collecting tissue to create a formalin-fixed paraffin-embedded sample is a process that can take many forms. Doctors have the option to biopsy diseased tissue, healthy tissue, or both. FFPE tissue blocks usually require a biopsy of only a few millimeters of tissue, making the process quick, efficient, and generally painless.

Immediately following the biopsy, the tissue is submerged in formalin for 18–24 hours to preserve the tissue’s pristine condition. Next, the preserved tissue is dehydrated before being embedded in IHC-grade paraffin wax. Immunohistochemistry (IHC) is a clinical method that uses antibodies to check for antigens with a fluorescent dye. IHC-grade paraffin wax has the ability to accept these dyes to be used in IHC testing.

By preserving the tissue in this way, researchers can cut sections from the FFPE block for closer examination.

FFPE Tissue Sections

FFPE sections are thin slices of tissue cut from FFPE blocks. These sections are then prepared using a microtome (a device that trims the tissue to precise depths ranging from a few micrometers to several millimeters). FFPE sections are used for a wide range of microscopic studies.

FFPE sections stored in archives have the ability to last up to 20 years! They offer a historical perspective on disease and a clear record of medical advancements. FFPE is a versatile preservation method; sections can be stored at room temperature, making FFPE sections a less expensive option to preserve and study the microscopic structures and the protein makeup of test samples. These sections can be mounted onto slides for examination under a microscope.

FFPE Tissue Slides

FFPE slides are thin sections of tissue samples mounted onto glass slides from FFPE blocks. These slides are typically stained for microscopic examination using various histological or immunohistochemical techniques. FFPE slides allow pathologists and researchers to visualize tissue morphology and study cellular structure under a microscope.

4 Common Uses of FFPE Tissue Blocks, Slides & Sections

1. Histopathology

Histopathology is the study of the change of tissue over time as a result of a disease. FFPE tissue samples are often used in diagnostic histopathology to diagnose diseases like cancer. Pathologists examine FFPE slides under a microscope to identify irregular cellular structures, tissue architecture, and other pathological features that indicate disease.

2. Molecular Biology Research

Scientists can extract DNA and RNA from FFPE sections to study genetic mutation, gene expression patterns, and epigenetic modifications associated with various diseases.

3. Drug Development

FFPE tissues are frequently used in the drug development process. Researchers use FFPE sections to assess drug efficiency or toxicity.

4. Forensic Pathology

FFPE blocks are valuable in forensic pathology for preserving tissue samples from cases involving biomatter. These samples can be archived for long periods of time, allowing forensic scientists to conduct postmortem examinations and investigations into the cause and manner of death.

FFPE Tissue Samples—A Closer Look at The Future

Formalin-fixed paraffin-embedded (FFPE) tissue samples have become vital in pathology and biomedical research. FFPE blocks, slides, and sections have become a standard in diagnostic histopathology to diagnose diseases since the preservation method’s inception in the 19th century. FFPE tissues are frequently used in the drug development process and forensic pathology to preserve tissue samples from cases involving biomatter. FFPE is a versatile preservation method; FFPE sections can be stored at room temperature, making them less expensive options to preserve and study the microscopic structures and the protein makeup of test samples.

Are you interested in the benefits of FFPE tissue blocks, sections, or slides for your research? Join top-rated academic institutions and biomedical companies that have made Superior BioDiagnostics their choice biobank supplier. Order your FFPE samples today!

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The Importance of Control Tissues

Lab technician preparing a FFPE control tissue slide

The Importance of Control Tissue in Medical and Scientific Research

Control groups are a necessary component of medical research. Control tissue samples are commonly used as a reference in biomedical research; these tissue samples can be collected from patients who are either entirely unaffected by the condition being studied or by using a healthy area from the patient’s body. Similar to control groups, control tissue samples are crucial to verifying results (and proving they are not the outcome of coincidence).

Control samples are used as benchmarks to diagnose or observe biopsy samples and are vital to establishing a treatment’s accuracy, reproducibility, and reliability. Researchers have launched biomedical research years into the future through hypothesis testing with control samples. In this article, we explore the importance of control tissue and FFPE samples in medical research.

Lab technician preparing a FFPE control tissue slide

What are FFPE Control Tissue Samples?

Formalin-fixed paraffin-embedded (FFPE) tissue samples are preserved using formalin and then embedded in paraffin wax and are commonly used as control samples in medical diagnostics. FFPE control tissue samples are great for experimental tests. The wax allows researchers to examine multiple extremely thin and fragile sections from a single biopsy.

According to the National Library of Medicine, “Pathology departments routinely archive vast numbers of FFPE blocks as compared to frozen tissues. This largely untapped resource represents an extensive repository of tissue material with a long-term clinical follow-up, providing a valuable resource for translational clinical research.”

FFPE control tissue creates standardization and quality control. These tissues provide a stable reference point for experimental procedures, ensuring that tests are performed consistently across different laboratories over time.

Validation Tissue & Benign Tissue Samples

Validation tissues are often used to compare experimental findings/diagnostic attempts. These samples are chosen because they show distinct characteristics that accurately represent the illnesses studied. Validation tissues are control measures to guarantee the quality and repeatability of findings. Researchers can detect and correct an experiment’s inconsistencies or errors using the tissues’ known characteristics.

Benign tissue samples are other types of control tissue collected from areas of the body that exhibit non-malignant, non-cancerous, or otherwise healthy characteristics. These samples serve as comparisons in diagnostic research. Oncologists have advanced biomarker studies by examining benign samples to create personalized cancer treatments. This customized treatment allows doctors to target the illness efficiently. Benign samples create a baseline for comparison with diseased tissue. Researchers can gain insights into illness progression, biomarker discovery, and therapeutic targets by analyzing the differences between benign and diseased tissues at the molecular, cellular, or microscopic levels.

Did you know that 75%–85% of biopsies lead to a benign result diagnosis? These frequently studied samples are in high demand for biomedical research. As your trusted biobank, Superior BioDiagnostics provides high-demand samples to keep your research moving.

The Future of Biodiagnostics

Control tissue samples are used as independent variables in clinical research and diagnostics. They serve as uncorrupted benchmarks that researchers can compare with test samples to diagnose and monitor conditions. With formalin-fixed paraffin-embedded (FFPE) samples, validation samples, and benign samples, researchers have been able to better understand and treat various conditions.

FFPE samples create standardized, quality-controlled results, whereas validation studies help researchers confirm experimental findings. Finally, benign tissue samples are crucial comparators in biomedical research, particularly in studying diseases such as cancer. These samples have helped treat, diagnose, and prevent diseases advancing the medical industry.

Today, clinical research is advancing rapidly, and the need for control tissue samples is growing daily. With Superior BioDiagnostics, you will have access to high-quality control tissue samples from various sites such as lung, brain, melanoma, breast, cervical, ovarian, and more to advance your research. If you’re looking for reliable control tissue samples, we’ve got you covered. Contact Superior BioDiagnostics today to order the tools for your next scientific breakthrough.

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What is Paraffin? Everything You Need To Know

What is Paraffin? Unlock The Potential of Biomedical Research

You may heard of paraffin, but likely don’t know exactly what it is. The unique substance can (and is) used widely in diverse industries. Paraffin can be found in beauty products and candles, but this incredible tool is particularly crucial in biomedical research.

Biomedical researchers now have the ability to seal tissue samples in paraffin and formalin, allowing them to examine even thinner tissue samples under a microscope than they were able to previously. By preserving human tissue samples in a paraffin and formalin compound, researchers can conduct various tests on tissue samples, diminishing the need for additional biopsy procedures. Keep reading to learn the unique and groundbreaking ways that paraffin is used throughout various industries.

What is Paraffin?

What is Paraffin?

Paraffin is derived from petroleum and shale oil. The substance is well known for its colorless, odorless, and waxy solid properties and its various applications. Liquid Paraffin, also known as mineral or white oil, has unique lubricating properties. Paraffin oil, sometimes called kerosene, is the byproduct of refining petroleum oil to fuel lamps and heaters.

Paraffin can remain in a solid state at room temperature but can also be melted easily with temperatures as low as 120℉. Thus, the versatile substance is most often found as wax and used in candles and cosmetics. Nevertheless, paraffin is also known for its critical role in preserving human tissue samples for biomedical research.

Paraffin For Tissue Preservation

Perhaps paraffin’s most useful duty is as a biomedical stabilizer. Researchers now have the ability to take smaller biopsy samples and examine the samples in great, transparent detail with the help of paraffin. Formalin-fixed Parafin-Embeded (FFPE) is a fantastic biomedical tool that prevents decay and enables the thorough examination of the tissue. Surrounding the sample with melted wax, or liquid paraffin, protects it from decay. FFPE is a preservation method that maintains the tissue sample’s composition—allowing researchers to examine thin, fragile layers without fear of damage. Samples preserved using FFPE also allow for the long-term storage of tissue samples and precise, reproducible results in histopathological research.

The use of paraffin, particularly FFPE tissue samples, mitigates every bioresearcher’s fear of encountering a false positive caused by a decaying sample. By studying FFPE tissue samples, scientists have made significant progress in analyzing genetic mutations, identifying targets for treatment, and predicting biomarkers. FFPE allows physicians to develop personalized approaches to treatment, which have led to better outcomes for patients.

Research and Diagnostics Uses

Formalin-fixed paraffin-embedded tissue specimens are used in biomedical research and clinical diagnostics to understand disease and predisposing biomarkers. Through studying FFPE samples, researchers have developed a deeper understanding of various diseases’ molecular and cellular characteristics, including cancer, infectious diseases, and neurological disorders.

FFPE tissue specimens are crucial for diagnosing diseases, evaluating their severity, and determining the best course of treatment for patients. These specimens are utilized in molecular diagnostic tests, like polymerase chain reaction (PCR) and next-generation sequencing (NGS), to identify genetic mutations and other changes related to the disease.

Is Paraffin Wax Toxic?

Thankfully, paraffin wax on its own is considered safe and non-toxic. It is a trusted substance often used in cosmetics, candles, and food packaging. However, when used in combination with formalin, paraffin can become toxic. Though paraffin wax is a safe and versatile option for tissue preparation, the process of preparing FFPE samples requires formalin, which is known to be poisonous and should be handled professionally.

Yield Clear Results With Paraffin-Embedded Tissue Samples

Paraffin preserves the integrity of tissue samples and enables the accurate analysis of formalin-fixed paraffin-embedded (FFPE) tissue samples. By encasing tissue specimens in a solid wax matrix, paraffin enables long-term storage and allows the safe examination of thin, delicate sections. Paraffin has advanced, and will continue to advance, pivotal tissue preservation techniques in biomedical research.

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The Most Common Types of Tissue Samples and Their Uses

The Most Common Types of Tissue Samples and Their Uses

Human Tissue and Biological Samples for Use in Research: 3 Common Types & Their Purposes

Human biological samples are a staple of scientific research. Whether collected from living or diseased human patients, these specimens are vital for various areas of health care. In routine clinical care, tissue and biological samples are used for diagnosis, prognosis, and monitoring of various diseases. On the other hand, in a research context, these specimens are crucial for creating new treatments, understanding human biology, and advancing medical knowledge.

Have you ever wondered what types of specimens are used in research and medical care? This article addresses 3 common types of human and biological samples used in various scientific fields. You’ll learn about the common types of tissue samples, how these specimens are collected, what type of tissue is best for DNA extraction, and more. If you’d like to learn more about the fascinating world of tissue samples in research, keep reading!

The Most Common Types of Tissue Samples and Their Uses

3 Common Types of Human Tissue and Biological Samples Used in Research

1. Epithelial, Connective, Muscle, and Nervous Tissue Samples

There are numerous types of tissue in the human body. Human tissue samples are often organized into four categories:

  • Epithelial Tissue: Epithelial tissue is found in your organs and internal and external body surfaces and is the most prominent tissue in glands. The lining of your intestines and respiratory tract, sweat glands, and the outer layer of your skin (epidermis) are a few types of epithelial tissue in your body. 
  • Connective Tissue: Structures that support and protect other tissues or organs in the human body. Connective tissue often stores fat, aids in transporting nutrients between tissues and organs, and helps restore damaged tissue. Connective tissues include bone, cartilage, lymphatic, and fat tissue. 
  • Muscle Tissue: Muscle tissue comprises cells that shorten and contract to move different body parts. Muscle tissue is often arranged in layers and surrounded by connective tissue. The 3 types of muscle tissue are skeletal, cardiac, and smooth. 
  • Nervous Tissue: The main tissue component of the nervous system. Nervous tissue comprises neurons and neurological cells that control and coordinate countless body activities. This tissue type is prevalent in the brain, spinal cord, and nerves.

The body’s various anatomical regions usually include multiple of the types of tissue samples mentioned above. For example, the lungs are lined with epithelial tissue, supported by connective tissue, regulated by nervous tissue, and contract and relax with smooth muscle tissue. Whether you’re collecting tissue from the brain or cervix, multiple types of tissue samples are most likely present in the anatomical site. Once collected, properly preserving the human tissue samples is essential. Standard preservation techniques include fixing specimens in formalin and embedding in wax, known as Formalin-Fixed Paraffin-Embedded (FFPE) tissue, or rapid freezing in liquid nitrogen, referred to as fresh frozen tissue. Preservation helps maintain the tissue’s cellular structures and molecular makeup, crucial for accurate research results.

How Are Tissue Samples Used in Research?

Human tissue samples are invaluable sources of information for researchers, aiding in advancing scientific research and improving our understanding of health and disease. Here are a few areas of study that use human tissue samples:

  • Biomarker Discovery: Tissue samples help researchers identify biomarkers, which are molecules that point out a specific disease or physiological state. Biomarkers aid in early disease detection, diagnosis, and monitoring. Immunohistochemistry (IHC) is a common technique used in biomarker analysis, determining the location of a particular protein in the tissue or call sample. FFPE tissue blocks collected from individuals carrying various diseases are usually the preferred tissue type used in biomarker research.
  • Disease Research: Biospecimens assist researchers in understanding how diseases affect the body at a cellular level. For instance, FFPE malignant tissue samples are analyzed for better insight into tumor growth, metastasis, and microenvironment. 
  • Drug Development and Testing: Various pharmaceuticals are tested on different types of tissue samples to assess their safety and viability before progressing to clinical trials. Drug testing also includes testing for pharmaceuticals’ potential side effects or toxicity. Drug development can involve numerous FFPE, fresh frozen, or fresh specimens collected from differing anatomical regions. 
  • Neuroscience Study: Normal, malignant, and disease-state brain tissue samples are critical in understanding neurological diseases such as Parkinson’s, Alzheimer’s, and multiple sclerosis. 

Numerous additional research fields use human tissue samples, including developmental biology, immunological studies, genetic analysis, regenerative medicine, and more. There’s no doubt that human tissue samples are paramount to our understanding of the human body and its intricacies.

2. Biofluids

Biofluids is the shortened term for biological fluids. Biofluids are collected from the human body in primarily 3 ways: excretion (e.g., sweat), secretion (e.g., breast milk), or extraction (e.g., blood). Here’s a list of the common forms of biofluids used for research purposes:

  • Blood
  • Urine
  • Sweat
  • Cerebrospinal fluid
  • Bile
  • Breast Milk
  • Plasma
  • Saliva
  • Stool
  • Swabs (nasal, oral, and vaginal fluids)

How Are Biofluids Used in Research?

Biofluids are primarily used to identify, diagnose, and monitor illnesses. However, that’s not all they offer to scientific research; biofluid specimens also make it possible to detect harmful substances in the body, discover the amount of specific proteins or hormones present, and estimate the concentration of drugs. Additionally, these fluids are necessary for biomarker studies, helping scientists and medical professionals track the biological components associated with certain diseases.

In 2020, biofluids proved especially important when COVID-19 instigated a worldwide lockdown. People were diagnosed with COVID-19 using a simple nasal swab during this period. Researchers had to obtain sufficient swab samples from patients with suspected COVID-19 (asymptomatic and symptomatic) and subjects without exposure to COVID-19. Without biofluids, researchers and medical professionals wouldn’t have been able to diagnose or study COVID-19.

3. Cells

Cell samples are groups of cells that can be obtained from biofluids, biopsies, or tissue samples. Below is a list of cell sample types used in scientific research:

  • Myoblasts
  • PBMCS
  • Buffy Coat
  • Bone Marrow
  • Mononuclear Cells
  • Fibroblasts
  • Epithelial Cells
  • RBCs

How Are Cell Samples Used in Research?

Countless researchers use cell samples for scientific analysis. Here are 2 of the common scientific areas to which cell samples contribute significantly:

  • Drug Development: Before new drugs are released, testing their safety and efficacy using cell samples is essential. Researchers utilize human cells, separated from blood or tissue samples, to assess how drugs could react to cells, their toxicity, and their possible healing effects. This testing is crucial for scientists to perform before advancing to animal models and human clinical trials.
  • Cell Biology Research: Basic cell biology research is integral to understanding a cell or tissue type’s inner workings. While some scientists may use immortalized cell lines, this field of study often requires researchers to obtain primary human cells from patients that carry the disease or indication of interest.

Human cells contribute to cancer research, regenerative medicine, and genetic and molecular biology studies. The main advantage of human cells is that they allow scientists to simplify a disease and focus on a small number of variables. Human cell samples help us better understand basic physiology and dive deeper into numerous diseases affecting countless subjects.

3 FAQs Regarding Tissue and Biological Samples for Use in Research

Here are 3 popular questions we hear regarding specimens that are used in medical research:

1. What’s the best tissue for a DNA sample?

Tissue collected from the brain, heart, or kidney is best for DNA samples.

According to the National Library of Medicine, “Our study suggested that quality and quantity of DNA extracted from tissues of putrefied unidentifiable human corpse was best seen in brain followed by heart and kidney preserved at -80℃ and 4℃. Muscles were found to be least useful for DNA extraction.”

2. How are human tissue and biological samples collected?

Biobanks, hospitals, and laboratories collect tissue and biological samples from voluntary donors. Patients can donate the leftover tissue samples, blood, and other specimens to these professional institutions following lab tests, surgeries, or other medical appointments. Medical facilities like biobanks prepare, store, and keep track of these samples, providing them for international research purposes. Researchers can then order specific types of tissue and biological samples from these facilities, aiding them in learning more about human health and the overall quality of life.

3. Which preservation method is the best for tissue samples?

FFPE is often the gold standard for tissue preservation. Researchers have relied on FFPE tissue samples for decades, knowing this form of conservation and storage holds together the specimens’ original structures and molecular makeups. Since FFPE tissue samples can be stored for up to a decade, scientists rely on this form of preservation for long-lasting studies and research purposes.

Order Quality Tissue and Biological Samples for Your Research Purposes

Do you need specific tissue and biological samples for use in your unique research purposes? At Superior BioDiagnostics, we have thousands of tissue samples ready to satisfy your scientific needs. Our biobank is stocked with normal, malignant, and disease-state FFPE tissue from various anatomical sites such as the brain, lungs, skin, and more. Don’t wait to receive the highest-quality tissue samples for your analysis. Contact Superior BioDiagnostics’ team to order your FFPE tissue samples today!

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How to Prepare Tissue Samples For Microscope Slides: A Step-By-Step Guide

How to Prepare Tissue Samples For Microscope Slides: A Step-By-Step Guide

Histology technicians play a significant role in biological research. Without these scientific experts, we wouldn’t have tissue slides carrying thin sections of biospecimens ready for microscopic analysis. Tissue samples prepared for microscope slides have radically impacted science; researchers can study cellular structures, disease traits, and the effects of various treatments on specimens. Pathologists can accurately diagnose diseases such as cancer, inflammatory conditions, and bacterial infections. Without histology technicians, we wouldn’t have tissue samples properly prepared for microscopic analysis. 

You may ask the question, “How do histology technicians prepare tissue samples for microscope slides?” In this blog, we share the 5 steps it takes to prepare human tissue samples for microscopic study. Whether you’re an experienced histology technician or simply curious about what goes into microscopic examination, this article is your guide to preparing tissue samples for microscope slides. From the fixation of human tissues to various staining techniques, you’ll walk away knowing exactly how to prepare biospecimens for microscopic research purposes. 

What You Need for Tissue Sample Preparation

Before you get started, there is an essential list of tools you will need for tissue sample preparation. The supplies list depends on the tissue type and what you’re using the biospecimen for. However, here are some staples you’ll most likely need when you prepare tissue samples for microscope slides: 

  • Fixatives (e.g., formalin, glutaraldehyde, etc.)
  • Processing solutions (e.g., xylene, ethanol, and other solutions as needed)
  • Embedding medium
  • Microtome or cryostat
  • Staining agents
  • Water bath
  • High-quality slides and coverslips
  • Slide labels
  • Slide storage boxes

Remember that the supplies you need for tissue preparation vary depending on the tissue type, staining method, and studies to be conducted. Ensure that you follow the protocols and safety guidelines of your laboratory or scientific institution when prepping tissue samples for microscopic analysis.

Tissue Sample Preparation for Microscope Slides: 5 Simple Steps You Can Follow

Once you’ve gathered all the necessary material, you’re ready to prepare tissue samples for microscope slides. Whether you’re new to it or not, you likely understand how large of an undertaking tissue sample preparation is. That’s why we’re here to give you a complete step-by-step guide to preparing tissue samples for microscopic study. Below are the 5 steps you can follow to prepare tissue samples for microscope slides: 

Fix the biospecimens

After obtaining the fresh tissue sample, it must be fixated, whether that’s through freezing or chemical fixation. It’s important to start the fixation process immediately after collecting the biospecimen, ensuring that it holds its original structures and molecular makeup. In turn, you’ll get the best results! Fixation is critical for the rest of the tissue sample preparation. Fixation preserves the chemical composition of the biospecimen, securing and hardening the sample to initiate easy sectioning. Below are the two primary types of fixation that researchers use for tissue sample preparation:

  • Fixative Solution: Researchers immerse biospecimens in a chemical fixative solution for 6–24 hours shortly after collection. Neutral Buffered Formalin or Paraffin-formalin are popular, effective solutions scientists and laboratories use for chemical fixation. Fixative solutions must penetrate every part of the biospecimen, preserving the sample and preparing it for microscopic analysis. 
  • Freezing: Scientists submerge the tissue samples in a tissue-freezing medium, which is then immersed in liquid nitrogen. Freezing biospecimens is an alternative to the fixative solution method and is preferred by researchers who need an immediate diagnosis.

Fixing human tissue samples, whether by freezing or using a chemical fixative, assists in preserving specimens and preventing degradation. Once you fixate the biospecimens, they’re ready to be processed. 

Process the tissue samples

Tissue processing can be performed with an automated machine or by hand, preparing the biospecimen for sectioning. Here are three general steps involved in tissue processing:

  1. Dehydration: Before converting the biospecimen into a solid form appropriate for sectioning, it must undergo dehydration. Ethanol is a popular agent used for the dehydration process. Ethanol removes water from the tissue sample and hardens it for microscopic use. Researchers immerse the specimen in multiple ethanol solutions of increasing intensity, ensuring that the tissue is free of water and formalin. 
  2. Clearing: After the submergence of ethanol and before the embedment of wax, the tissue sample needs an in-between “clearing” medium that is compatible with both paraffin wax and ethanol. Xylene is a popular solvent that rids tissue of ethanol and prepares it for infiltration of wax. 
  3. Embedding: Using an embedding center, the biospecimen is placed into a mold of molten wax (typically paraffin wax), forming what is called a “block” ready for sectioning. The newly created block is then cooled and prepared for thin-section cutting. Embedding also preserves the cellular structure of a tissue sample, making it more compatible with succeeding tissue sample preparation steps.

Processing helps preserve the integrity of tissue samples, leading to more accurate analysis and improving scientific diagnostics. Processed biospecimens also absorb stains more effectively and can be stored long-term in a biobank if needed. In summary, proper processing sets you up for success during the rest of the tissue sample preparation procedure.

Cut the biospecimens into sections

Now, your biospecimen is ready to be cut into sections on a microtome. First, the wax is removed from the surface of a block, exposing the tissue sample. Using a microtome, the biospecimen is sliced into sections no more than 4–5 micrometers. A microtome can cut continuously, creating a “ribbon” of tissue sections that are perfect for microscopy. If the sample is frozen, you’ll use a cryostat to cut it into tissue ribbons. These specimen ribbons can then be placed in a warm water bath to flatten. From here, tissue samples are easily collected for staining and examination on a microscopic slide. 

Stain the samples

Staining specimens is a vital element of tissue sample preparation. While there are numerous staining techniques, we’ll highlight a few of the most common methods below: 

  • Hematoxylin and Eosin: The use of Hematoxylin and Eosin (H&E) is the most widely used staining technique for pathologists. Hematoxylin is a dye that stains acidic structures, while eosin is a counterstain done after hematoxylin that marks the sample’s basic structures. The result? Cell nuclei are often colored blue/purple, and other cellular structures that attract eosin (eosinophilic structures) are stained with a pink/red hue. RNA in ribosomes or the rough endoplasmic reticulum, for instance, would be stained blue, while the cytoplasm would be colored pink. 
  • Gram Staining: Gram staining is used primarily to differentiate bacterial species according to the physical and chemical components of their cell walls. With the help of a gram stain, differing bacteria will change one of two different color sets (purple to blue or pink to red). Bacteria are then labeled as “gram-positive” or “gram-negative” according to their coloring. Gram-positive bacteria contain a hefty layer of peptidoglycan, making them appear purple. Gram-negative bacteria, on the other hand, hold a thin layer of peptidoglycan and other lipids in the cell wall, which washes out the violet in the decolorization process and stains them pink. Gram staining aids in diagnosing bacterial infections and the types of bacteria causing the illness.
  • Masson’s Trichrome: Masson’s trichrome staining is a popular method that produces multicolor results on biospecimens. In a trichrome staining procedure, collagen is stained blue, muscle tissue is colored red, cytoplasm is dyed pink, and nuclei have a dark brown tint. The trichrome technique can distinguish collagen from muscle and identify pulmonary fibrosis, cardiac fibrosis, chronic kidney disease, muscular dystrophy, and various tumors of muscle origin.

Staining tissue samples enhances scientific studies by identifying a tissue sample’s components such as proteins, lipids, and carbohydrates. Varied stains can also aid in diagnosing diseases, differentiating normal and abnormal specimens, and detecting the presence and location of particular proteins. Overall, staining helps histologists better understand the minuscule structure and function of normal, malignant, and disease-state tissues. 

Mount the tissue sample sections for microscopic examination

After the biospecimen has been stained, the tissue sample section is ready to be mounted between a slide and coverslip, ensuring that it’s secure and ready for microscopic examination. Outlined below are the steps of mounting a slide: 

  1. Apply a single drop of an aqueous-based or resinous mounting medium onto the tissue section.
  2. Hold the coverslip at a 45° angle and allow the drop to spread to the edge of the slip. 
  3. Gently let go of the slip so it covers the tissue section, allowing the medium to spread slowly and cover the biospecimen completely.

It’s important to utilize a clearing agent that’s compatible with the mounting medium, preventing issues in the mounting stage. It’s also necessary to label each slide with the patient ID, tissue type, and date. After mounting your biospecimen, it’s ready to be stored for observation under a microscope! Store tissue samples in a cool, dark place to prevent the fading of stains.

Receive the Finest Tissue Samples Prepared for Microscopic Study

Do you want to skip the tissue sample preparation process and invest in high-quality biospecimens prepared exclusively for microscopic analysis? Superior BioDiagnostics has everything you need and more. Our biorepository is stocked with thousands of normal, malignant, and disease-state FFPE tissue samples ready for your research purposes. We provide biospecimens from just about every anatomical site in the form of blocks, slides, and sections. 

We collect tissue samples that are 100% US-procured and processed, ensuring you receive the purest biospecimens for microscopic analysis. Superior Biobank’s team can also include data on the tissue sample’s tumor type (if applicable), TNM stage, histologic grade, and donor demographics to improve your discoveries. Contact Superior Biobank to order pre-prepared tissue samples for your microscopic study.

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Biospecimen Storage & Preservation: A Guide for Researcher

Biospecimen Storage & Preservation: A Guide for Researchers

Biospecimens are a key part of modern scientific research. After collection, tissue samples are preserved and prepared for distribution, ensuring researchers receive only the highest-quality tissue samples. During the preservation process, it’s vital to maintain biospecimens’ original structures and molecular makeups. One misstep in this process could compromise the tissue sample’s effectiveness for research purposes and drug development. This information raises the question: how exactly do you store biospecimens effectively?

In this blog post, we share everything you need to know about biospecimen storage. We answer common questions such as, “What’s the best way to preserve tissue samples?” and “Why is tissue preservation important?” We also share 3 best practices for the tissue preservation process. Keep reading to find out how you can keep tissue samples in top condition from collection to distribution!

Why is Tissue Preservation Necessary?

Proper biospecimen storage is a vital element of scientific research. Whether you’re preparing tissue samples for microscopic slides or need to extract the biospecimen’s molecules for DNA and protein analysis, tissue preservation is a skill you need to learn or, at the very least, understand.

Human tissue samples for use in oncology, spatial biology, pathology, and other biological research fields can lose their integrity and reliability without the proper temperatures and preservation conditions. The primary purpose of tissue preservation is to maintain the tissue’s original molecular and structural state without losing quality and deterioration.

Tissue preservation is especially important for long-term research and studies. Well-preserved biospecimens can be stored at a biobank for countless years, providing invaluable resources for a variety of medical research purposes. Long-term tissue sample storage allows researchers to re-examine high-quality biospecimens over the years in light of new scientific discoveries or upgraded techniques. 

Let’s take a look at a few of the best preservation methods for tissue samples.

3 Common Preservation Techniques Used for Human Tissue Samples

There is a diverse range of preservation methods within biospecimen storage. From freezing tissue samples in extremely low temperatures to fixating specimens in chemicals, tissue preservation is a learned science all on its own. However, the scientific community has relied on several popular preservation methods over the past few decades. Below are the 3 common preservation techniques scientists use for biospecimen storage: 

Snap-Frozen and Cryopreservation

Perhaps the most well-known preservation method is the act of freezing tissue samples. Scientists take one of two paths when freezing biospecimens: snap-freezing or cryopreserving. Let’s take a closer look at each of these preservation processes: 

Snap-freezing is the process of rapidly cooling tissue samples to temperatures below -70℃ using dry ice or liquid nitrogen. If using liquid nitrogen, researchers will place collected biospecimen samples on a cryomold or wrap them in foil, immerse them in the nitrogen, and immediately freeze them. On the other hand, researchers can use the dry ice method, placing the specimen on prepared dry ice. This method takes longer than liquid nitrogen and isn’t the preferred method. Snap-frozen tissue samples are stored in -80℃ freezers.

Cryopreservation is a long-term method of preserving samples at very low temperatures (-196℃ to -250℃) to preserve the overall integrity of cells and tissue. Cryopreservation involves the use of cryoprotectants (e.g., ethylene glycol, dimethyl sulfoxide, glycerol, etc.) to protect biospecimens from damage during the preservation process, specifically from ice crystals forming. 

Freezing tissue samples, whether through cryopreservation or snap-freezing, is a reliable preservation method used for long-term biospecimen storage. Tissue samples can be frozen for several years, maintaining their original structure and quality for an extended period.

Formalin-Fixed Paraffin-Embedded

Chemical fixation and embedding is another trusted preservation method for tissue samples. Formalin-fixed paraffin-embedded (FFPE) biospecimens are immersed in a fixative of 10% formalin. Formalin immediately stops the biological and cellular activity within specimens, stopping the decay process right after fixative immersion. After 18–24 hours, fixed specimens are then dehydrated using ethanol and prepared for embedment. The tissue samples are then embedded in paraffin wax, making it easier for the specimens to be sliced and mounted on microscopic slides. 

FFPE tissue samples can be stored indefinitely in biobanks, hospitals, laboratories, or research centers. For quality assurance reasons, fixed and embedded specimens should be stored at 4℃ with limited light exposure. FFPE tissues are compatible with a variety of histological staining techniques, such as immunohistochemistry (IHC), allowing researchers to find and locate protein structures within the biospecimen. Fixing and embedding tissue samples preserves the cellular and tissue structure of specimens, which is essential for histopathological studies. If stored at room temperature, FFPE samples can be stored for an extended amount of time, making it possible to curate extensive archives of specimens that can be used for future analysis. The fixing and embedding process of FFPE specimens is also well-standardized across the board, leading to consistently pure samples, which is paramount for comparative research.

Other Short-Term Techniques

Apart from freezing and FFPE techniques, there are other shorter-term preservation methods for biospecimen storage. Hypothermic preservation, for example, slows down the chemical processes occurring in human tissues and protects refrigerated specimens from cold-induced injuries. Tissue samples are bathed in a cold storage solution, preserving them for no longer than 1 to 2 days in low temperatures. 

Depending on the type of tissue sample, researchers can also store specimens in a refrigerator with a temperature of 2–8℃. Biospecimens stored in a refrigerator will stay preserved for just a few days, so it’s important to utilize these samples quickly for research purposes.

3 Best Practices for Tissue Preservation

Biospecimen storage is an extremely important step of tissue procurement and preservation. Here are 3 best practices to implement when storing tissue samples:

  1. Label Tissue Samples: Label tissue samples with collection date, tissue type, and preservation technique. You can also include donor demographics such as age, gender, and ethnicity. Labeling biospecimens with as much information as possible reduces errors down the line and maintains traceability for future research needs.
  2. Avoid Contamination: Rapid processing is a top priority in tissue preservation. If you want to ensure quality control, minimize the time between human tissue collection, transportation, and preservation as much as possible. Make certain that tissue samples are being handled with care and adhering to ethical guidelines 100% of the time. Rapid processing prevents the risk of unnecessary tissue contamination. 
  3. Prevent Degradation: Consistently check the condition of the stored biospecimens, ensuring the preservation methods are effective. Monitor and log the biospecimen storage temperatures, preventing degradation and breakdown of structural integrity. 

Consistency is key when it comes to tissue preservation. If you prioritize labeling samples, rapid processing, and monitoring tissues day in and day out, stored biospecimens will stay in top-notch condition. 

Preserved Tissue Samples For Your Research Goals

Superior BioDiagnostics understands how important it is to obtain tissue samples that are preserved in top-tier facilities. We provide researchers, laboratories, medical facilities, and more with high-quality biospecimens. Our team’s #1 goal is to maintain each tissue sample’s original structural and molecular state, ensuring you get the purest biospecimens for your research needs. 

Our biobank carries thousands of FFPE tissue samples, including normal, malignant, and disease-state biospecimens. Superior BioDiagnostics collects 100% US-procured chemically fixed and embedded tissue samples from the following anatomical sites: breast, lung, brain, muscle, skin, and more. Contact our biorepository to order specimens in the form of blocks, slides, and sections for your analysis.