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The Importance of Human Tissue Samples and Bio-Fluid Biospecimens in Cancer Research

Researchers require access to unique tools and materials, including human biospecimens and biofluids, to study cancer and other diseases. Therefore, since most biological materials are both fragile and perishable, researchers must take special care to process and preserve them properly to ensure viability.

Fresh human tissue biospecimens and biofluids are, in fact, best for modeling living tissue in the human body. For scientists and researchers, fresh tissue provides a platform for early-stage immunotherapy development.

Additionally, individual tumor cells (either primary or dissociated) allow for the characterization of tumors and the exploration of important molecular and cellular pathways.

Usually, there are two major tissue preparation methods used: FFPEs and fresh frozen tissue samples.

For a long time, researchers have processed human tissues as FFPE tissue blocks, also known as formalin-fixed paraffin-embedded. Specifically, researchers saturate these human tissue samples with formalin and then embed them in a block of paraffin wax (referred to as formalin-fixed paraffin-embedded or FFPE tissue).

Moreover, with the invention of reliable ultra-low temperature freezers and ample availability of liquid nitrogen, researchers have found it feasible to freeze tissue as a second means of long-term storage.

Fresh Frozen Tissue Samples

Frozen tissue refers to tissue samples that have been rapidly frozen, typically using liquid nitrogen, for preservation and analysis. Moreover, this process is crucial for preserving the structural integrity and biochemical components of the tissue, allowing for various microscopic and molecular studies.

Additionally, human tissue degrades quickly at room temperature and does not store well when kept in a standard “-20” food or household freezer. Therefore, you must freeze the tissue samples as soon as possible, and then keep it very cold.

Furthermore, researchers use frozen tissues for molecular genetic analysis – especially when they dip the biopsy materials in liquid nitrogen in a method called “flash freezing,” and then store them in an ultra-cold freezer at less than -80 degrees Celsius.

Consequently, researchers require a dedicated ultra-low temperature freezer to keep the human tissue samples always frozen.

Collection and Processing of Fresh Frozen Tissue Samples

Researchers primarily use fresh tissue biospecimens to isolate unique cell types or prepare smaller 3D structures. Therefore, they must carefully collect human tissue in the appropriate culture media and process it within specific time and temperature parameters.

To isolate cells from tissue samples, researchers must follow subsequent digestion or disintegration steps. They need to undertake this process meticulously, adhering to special protocols and lab conditions. The choice between mechanical or enzymatic digestion depends on the type of tissue being processed. Additionally, the protocol should account for the desired cell type, as the conditions will vary accordingly.

While blood samples do not require digestion or fragmentation, isolating fresh and functional blood cells involves more requirements and specifications than the traditional buffy coat isolation method.

FFPE Tissue Samples

Formalin-fixed paraffin-embedded (FFPE) tissues serve as the most common sources of archived material. For decades, pathologists at hospitals have created and archived FFPE tissues.

Whenever they study a biopsy from a patient, they archive some of this material for later use, often referring to it or seeking second opinions during the patient’s treatment. Researchers also preserve donated human tissues and materials collected from animals to build archives for future study. These archives, known as “biobanks,” can be developed by universities and hospitals or created for commercial purposes by companies serving the research community.

Because these archival materials have accumulated over a long period, they provide a historical perspective and serve as a rich source of research material.

FFPE tissue blocks can be stored in a cabinet at room temperature, making it cost-effective to create a large, stable collection. The formalin and wax preserve fragile structures within and between the cells, making FFPE tissue ideal for those studying cell and tissue morphology, such as pathologists diagnosing cancer from preserved biopsies. The proteins in FFPE tissue remain intact, not just the structures visible under a microscope.

Histologists can employ fluorescently labeled antibodies or other tagged antibodies that specifically bind to certain proteins, allowing them to determine the presence of these proteins in specific cells within tissues. They can also assess how the locations and amounts of these proteins differ between diseased and healthy tissues. This technique is known as immunohistochemistry (IHC).

Finally, since FFPE is a well-established method for tissue storage, pathologists are well-versed in examining and diagnosing conditions from FFPE tissue biopsies.

Fresh Frozen Tissue Samples Vs FFPE Tissue Samples

Frozen tissue effectively preserves DNA, RNA, and native proteins. However, researchers can quickly lose frozen tissue archives due to power outages, mechanical failures, or carelessness in the lab.

Pathologists also find frozen tissues less familiar, as they typically prefer making diagnoses through microscopic analysis of FFPE tissue.

FFPE tissues excel in creating extensive archives for research. Once prepared, FFPE tissue remains robust and does not require special equipment to maintain stability for decades.

With decades of experience, pathologists confidently diagnose conditions using FFPE tissue. Additionally, FFPE samples can be utilized for certain immunohistochemistry (IHC) studies.

However, FFPE tissue samples may not be suitable for analyzing native proteins and are generally less effective for genetic analyses, such as PCR, qPCR, or next-generation DNA sequencing, which are becoming increasingly common in research.

Human Bio-Fluids

Human biofluids are the biological liquids found within an organism’s body, including whole blood, lymph, and interstitial fluid.

These fluids play a crucial role in transporting nutrients, removing waste, and maintaining overall health. Researchers can also examine biofluids for diagnostic purposes.

A human biofluid is a water-based liquid containing solutes essential for bodily functions, resulting in a highly variable chemical composition that depends on the specific body region.

Researchers utilize biofluids such as blood products, human saliva, serum, plasma, and urine in clinical studies and translational and biomarker research.

In medical contexts, healthcare professionals analyze biofluid samples for diagnostic evaluations, aiding in the identification of diseases and conditions.

Biofluids, including blood, urine, saliva, and other bodily fluids, are vital for biomedical research. They provide valuable insights into disease, drug effects, and overall health.

Researchers employ biofluids in various fields, including drug discovery, biomarker studies, and the development of diagnostic tools.

Drug Discovery and Development

Researchers use biofluids to assess drug concentrations and effects in the body, facilitating the development of new therapies.

Biomarker Studies

By analyzing biofluids, scientists can identify and track measurable biological components (biomarkers) linked to specific diseases, which aids in early detection and monitoring.

Diagnostic Tools

Biofluids can be used to develop diagnostic tests for various conditions, such as infectious diseases, cancer, and autoimmune disorders.

Research Applications

Researchers utilize biofluids in various fields, including:

• Oncology: Examining cancer development and treatment responses.
• Infectious Diseases: Investigating infection mechanisms and developing antiviral therapies.
• Hematology: Studying blood disorders and their underlying causes.
• Metabolism: Analyzing individuals’ metabolic profiles to understand disease pathways.
• Neurology: Exploring the effects of neurological disorders on brain fluids and other bodily fluids.
• Reproductive Health: Investigating how reproductive health conditions impact biofluids.

Types of Human Bio-Fluids

Here are some of the different types of human  bio-fluids available for research.

• Whole Blood
• Plasma
• Serum
• PBMC
• Amniotic fluid
• Bronchoalveolar fluid (BALF)
• Breast Milk
• Cell culture supernatants
• Cerebrospinal fluid (CSF
• Gastric fluid
• Peritoneal fluid
• Nasal fluid samples
• Pleural fluid (pleural lavage)
• Saliva
• Semen (seminal fluid)
• Synovial fluid,
• Vaginal secretions
• Urine