Cell culture is a technique enabling in vitro growth and analysis of cells outside of their host tissue, in an artificial environment. This enables intra and extracellular conditions to be more readily modified for scientific enquiry.

An early breakthrough involved chicken embryonic nerve folds maintained in saline solution, which established cell culture as a viable technique for tissue cells. Further developments arose with the “hanging drop technique”, suspending tissue samples in a drop of blood or serum in which cells spread to occupy the drop and divide (Taylor, M.W., 2014). In 1911 a prolonged cell culture was established from embryonic chick heart tissue, utilizing a modified hanging drop technique with incubation, followed by passaging of the tissue (Carrel & Burrows, 1911). The cells continued to grow and proliferate for three months, drawing the conclusion that tissue can be maintained indefinitely under optimum conditions.

  1. Hayflick put this theory to the test by successively sub-culturing cells once they had grown to fully occupy their growth medium. Using this technique with human fibroblasts, he established the first cell strain, which maintains the original karyotype of cells isolated from the tissue of origin. He demonstrated that eventually cells stop dividing and die, known as the Hayflick limit: a feature underlying cell strains, which occurs at 40-60 division cycles in human cells. Cell lines on the other hand can be grown indefinitely as their karyotype is abnormal, this allows indefinite testing using the same progeny, a valuable trait which has been integral to polio vaccine development.

Culturing of cells allows for better examination and isolation than in vivo, so mutants can be selected based on their genotype, morphology or antibiotic resistance, then subcultured to initiate a cell line. The HeLa cell line, which was derived from cancerous cervix cells removed from a woman in 1951, became the first human cells to grow relatively well in vitro.

A problem with using blood derived medium in cell culture was its poorly defined nature, making replicating results a problem. Fully defined liquid medium first developed in 1911 improved reconciliation of results. However, serum is currently still added as a component in cell cultures, promoting better growth due to its micronutrient availability, broad spectrum macromolecules and growth factors (Gstraunthaler 2013).

Disaggregation of cells from tissue is significant in cell culture and is achieved mechanically, enzymatically or via non-enzymatic chemicals such as EDTA. Tissue often contains many cell types and by disaggregating the cells, specific cells type can be easily isolated and propagated in fresh medium.

Aseptic technique to maintain sterile conditions is essential in cell culture, preventing microbial contaminants entering the culture medium which could cause putrification and introduce false positive results (Winston et al. 2007). Methods include heat and chemical sterilization, the use of latex gloves and biological safety cabinets to isolate specimens from environmental contaminants and vice versa.

Antibiotics, first introduced into culture media in 1940s, provide some degree of protection against common microbial contaminants. Penicillin and streptomycin for example target the bacterial cell-wall ribosome respectively, so do not affect eukaryotic tissues.

Cell culture incubators provide optimum temperatures to promote cell growth and maintenance. These are often used in conjunction with agitators to disperse cells, nutrients, dissolved gases and solutes throughout the media.

Cells can be grow on a 3D matrix utilizing collagen and other support structures that collectively simulate the extracellular matrix of tissue. This gives several advantages over a 2D monolayer for some cell types, as they show more natural behaviour, allowing greater accuracy in predictions for in vivo conclusions and generating more physiologically relevant results (Antoni et al. 2015).

Stem cell research was initiated after successful culturing of embryos isolated from mouse blastocysts in 1982. The potential of ESCs to differentiate into any cell type was a huge breakthrough in science and medicine. Subsequently in 1998 the first human ESCs were derived from human blastocysts and successfully cultured. Their innate pluripotency allowed for a relative abundance of difficult to acquire cell types to be studied in vitro.

Induced pluripotent stem cells, a more recent advancement, bypass the ethical considerations arising from ESCs as they can be derived from almost any cell. iPSCs were initially generated from human fibroblasts, genetically reconfigured to a state of embryonic cell pluripotency. Another advantage is their potential for supplanting damaged tissue in the donor, phasing out any risk of tissue rejection as is likely with embryonic stem cells (Singh et al, 2015).

Innovations in cell culture have enabled cells to be studied independent of the organism of extraction and continually improves disease diagnoses efficiency as well understanding of cellular biology, disease mechanisms and regenerative medicine.

 

Winston, L. G., Roemer, M., Goodman, C., & Haller, B. (2007). False-Positive Culture Results from Patient Tissue Specimens Due to Contamination of RPMI Medium with Cryptococcus albidus. Journal of Clinical Microbiology.

 

Antoni, D., Burckel, H., Josset, E. & Noel, G. (2015). Three-Dimensional Cell Culture: A Breakthrough in Vivo

 

Taylor, M.W., (2014) A History of Cell Culture.

 

Carrel, A., & Burrows, M. T. (1911). Cultivation of tissues in vitro and its technique. The Journal of experimental medicine, 13(3), 387

Gstraunthaler, G. ALTEX. (2003) Alternatives to the use of fetal bovine serum: serum-free cell culture, 20(4):275-81.

Singh, V. K., Kumar, N., Kalsan, M., Saini, A., Chandra, R. (2015) Mechanism of Induction: Induced Pluripotent Stem Cells (iPSCs). Journal of Stem Cells ISSN: 1556-8539 Volume 10, Number 1.