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

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.