BioIVT’s wide range of isolated cells can be applied in various areas of research. From autoimmune diseases to oncology, BiolVT’s expertise covers numerous disease indications and research applications.
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Researchers often struggle to select which cells to utilize in their research and when to employ them.
Cell lines, dissociated tumor cells, and primary cells all have their place in research. While there may be some overlap, each occupies a unique niche.
Immortalized cell lines have been a prevalent research tool for more than five decades. While they remain valuable, technological advancements have enabled the development of techniques to isolate and culture other cell types that are potentially more suitable for research applications.
What are these different types of cells? How are they derived? How do they relate to each other?
All cell types are derived from biofluids or tissue. There are four main types of cells.
Dissociated tumor cells (DTCs) originate from fresh tumor tissue that is dissociated into a single-cell suspension. The cells are subsequently cryopreserved without any additional modification.
Immune cell subpopulations can also be isolated from biofluids or tissue. Depending on the number of specific subsets in the starting material, various techniques can be employed to isolate the different sub-populations of immune cells.
If tissue is dissociated into one cell suspension and then the cells are placed into culture, rather than being cryopreserved, the resultant cell population is typically composed of epithelial cells or fibroblasts. These cells are often termed “primary culture cells,” as they grow in culture for a few passages but are not immortalized.
Primary culture cells and immune cells can be transformed into immortalized cell lines.
Immortalized cells
Immortalized cells can be propagated in culture continuously, making them particularly valuable, especially when intending to employ the same cells repeatedly in numerous assays. Well-established cell lines frequently have known genetic profiles and are well-characterized.
However, the primary limitation of cell lines is their considerable divergence from the source material, at least in comparison with other types of cells. These cells typically undergo intentional modification, so they may not be representative of in vivo conditions.
How DTCs are made
To obtain DTCs, the tissue is minced and then enzymatically and mechanically digested. Following this, the suspension is strained, washed, and frozen. Since DTCs originate from the dissociation of fresh tumor tissue, they constitute a diverse mixture of all the cells found in the tumor, potentially including tumor-infiltrating lymphocytes (TILs).
DTC products must be quality-checked and well-characterized. To begin with, the original tumor tissue must be reviewed by a pathologist to confirm the type of tissue and disease state. Mycoplasma, sterility, and human pathogen-free testing are essential for downstream applications, especially in culturing.
Short tandem repeat (STR) profiling is employed to verify the absence of contamination in these samples with known cell lines.
The implementation of a post-thaw cell count, growth assessment, and viability assessment provides researchers with an idea of how the cells will perform in additional downstream applications.
Examining the expression of common leukocyte markers is beneficial for characterizing DTCs. This data will vary with each tumor and is valuable for researchers exploring TILs as it can indicate the presence of certain leukocyte subsets.
DTCs vary among tumors. The cells from different tumors or donors will behave differently in culture. Some may adopt a fibroblast-like morphology in culture, while others appear more epithelial-like. Many will appear to be mixed cultures while others will not proliferate in culture at all.
DTCs offer the closest comparison to the original tissue while still providing the flexibility of working with cells.
An additional consideration when assessing DTC products is the availability of clinical data sets from the DTC donor—more detailed clinical data yields more variables for analysis. Another important factor is the availability of matched peripheral blood mononuclear cells (PBMCs) or cells from matched normal adjacent tissue.
Following dissociation, starting, and washing, DTCs are frozen, whereas primary cells are placed into culture. The resulting cell types are dependent on the starting tissue. Many of these cultures typically become epithelial-like or fibroblastic.
The more time primary cells spend in culture, the more phenotypic drift they will undergo, making them less representative of clinical research and reducing their value to researchers. As a result, primary cells are most effective when utilized after one or two passages.
The differences between primary cells and DTCs
Primary cells do not grow as quickly as cell lines; they are typically passaged approximately every two weeks, rather than every few days.
Although primary cells are frequently derived from tumor tissue, cells from other tissue types can be employed. Researchers may also be specifically interested in primary culture cells from diseased tissues, such as idiopathic pulmonary fibrosis (IPF) and cystic fibrosis (CF) lungs, and rheumatoid arthritis (RA) and osteoarthritis (OA) synovium.
Primary cells should undergo quality checks and characterization in the same way as DTCs—that is, a pathology review, contamination testing, and post-thaw growth checks. As primary culture cells frequently appear to be epithelial cells or fibroblasts, conducting a leukocyte marker expression evaluation is not as valuable.
Alternatively, primary culture cells can be evaluated for the expression of an epithelial cell marker (such as cytokeratin) or a fibroblast marker (like vimentin) to verify their epithelial or fibroblast cell type.
Compared to DTCs, primary culture cells are more purified populations, as culturing frequently results in the selective expansion of epithelial cells or fibroblasts over the other cell types present.
When these primary culture cells are derived from oncology tissues, they are called cancer-associated epithelial cells (CAEs) and cancer-associated fibroblasts (CAFs). When these cells originate from normal lung tissue, they are called Primary Parenchymal Fibroblasts or Primary Bronchial Epithelial Cells.
Primary culture cells are similar to cells in the original tissue, particularly if they have only been cultured for a short duration. Similar to DTCs, the availability of matched normal cells and PBMCs, as well as the presence of an entire clinical data set, quality check, and characterization data, are all essential considerations when examining primary cell products.
Due to the critical role of the immune system in disease advancement, researchers investigating various diseases necessitate immune cells from relevant donors. Immune cells are often isolated from several tissue types—typically bone marrow, spleen/lymph node or tonsil tissue, peripheral blood, and cord blood.
These isolations are frequently conducted by density gradient centrifugation, which produces a population of mononuclear cells (MNCs). Various cell types can be isolated from these mononuclear cells, such as T and B cells, natural killer (NK) cells, and monocytes. Hematopoietic stem cells can be derived from cord blood and bone marrow MNCs.
Samples for immune cell isolation can be obtained using various formats, including whole blood, buffy coats, CPT tubes, and leukopaks.
- Whole blood is most common and frequently collected in all biomedical settings. Various anticoagulants can be selected depending on the specific application.
- Buffy coats are derived from whole blood units enriched for MNCs.
- CPT tubes have a gel barrier that enables easy and quick PBMC isolation.
- Leukopak samples are collected by leukapheresis and have an extremely high yield of MNCs from an individual donor.
Cell applications
Cell products are beneficial for various applications. Cell products may be employed in biomarker discovery studies, particularly those from a wide variety of disease types that may not be obtainable in other formats.
Cells that best mimic vivo conditions will be the most suitable for these studies, making DTCs and primary cells the most appropriate cell products for biomarker discovery research.
Cell products are also valuable in drug discovery research. Having the correct disease type for candidate compound screening assays is essential, making a diverse inventory of diseased cell products invaluable to researchers.
Cell therapy is an emerging field of research. As DTCs, primary cells, and immune cells are directly derived from human donors with no alteration, they are of high importance to cell therapy researchers who might use them as targets for cell-killing assays or to validate gene editing techniques.
Cells from diseased tissue are frequently required for diagnostic development work. Access to various disease types (including respiratory disease, joint disease, and oncology) is therefore valuable to those developing novel diagnostic techniques.
Immunotoxicity is a significant factor in medical device validation. Access to a diverse, large inventory of immune cells from a broad range of disease indications, as well as from different species, is a valuable tool for those evaluating the immunotoxicity of medical devices.
Cell lines, primary cells, and certain DTCs can be integrated into 2D and 3D culture models. These viable human cells will provide a superior representation of the clinical environment, facilitating the generation of more pertinent models for drug screening and chemosensitivity testing.
Personalized medicine researchers can utilize BioIVT’s patient-derived cells to evaluate how specific disease cohorts will respond to different drug therapies, as its cell products provide close representations of the clinical scenario (particularly its DTCs).
About BioIVT
BioIVT, formerly BioreclamationIVT, is a leading global provider of high-quality biological specimens and value-added services. We specialize in control and disease state samples including human and animal tissues, cell products, blood, and other biofluids. Our unmatched portfolio of clinical specimens directly supports precision medicine research and the effort to improve patient outcomes by coupling comprehensive clinical data with donor samples.
Our Research Services team works collaboratively with clients to provide in vitro hepatic modeling solutions. And as the world’s premier supplier of ADME-Tox model systems, including hepatocytes and subcellular fractions, BioIVT enables scientists to better understand the pharmacokinetics and drug metabolism of newly discovered compounds and the effects on disease processes. By combining our technical expertise, exceptional customer service, and unparalleled access to biological specimens, BioIVT serves the research community as a trusted partner in ELEVATING SCIENCE®.
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