Key Factors to be Considered for Replacement of Cell Line Medium

Cell lines are permanently established cell culture, which will proliferate indefinitely given appropriate fresh medium and space. Lines differ from cell strains in that they become immortalized. Cell lines are most cost-effective and ethically viable resource for performing scientific research. The development of cell lines was idealized for their phenotype and genotype homogeneity over recurring cell populations.

Types of Cell Lines

Continuous Cell Lines

A continuous cell lines are the one that is capable of unlimited number of population doublings, often referred to as an immortal cell culture. Continuous cell lines are generally aneuploidy and often have a chromosome number between tetraploid and diploid values. There is significant variation in constitution and chromosome number among cells in population. Several noticeable properties of continuous cell lines include

1. Decreased density limitation of growth
2. Reduced serum requirement
3. Aneuploidy
4. Growth in semisolid media

Some normal cells do not generate continuous cell lines. For instance, normal human fibroblasts remain euploid during their life spam and usually around 50 generations will stop dividing, though they remain active for 18 months thereafter. On the other hand, epidermal cell have exhibited gradual growing lifespan with improvements in culture techniques. Increasing lifespan of cell lines is big challenge to producers. Therefore, number of investers are investing more in research and development activities to improve cell line’s life. Further, the increasing investment in the research and development activities has positive influence on the growth of Cell Lines Market.

Finite Cell Lines

Finite number of cell lines are capable of producing only limited number of population doublings after which the line ceases proliferation. Finite cell lines develop within primary cell cultures where the initial attempt at increasing the cell lines is made. Primary cell culture consists of independent or dependent cell types. Dependent cells require actual culture medium in order to expand. The culture medium delivers certain nutrients and materials required to sustain life of dependent cells. Independent cells don’t require culture medium meaning they can survive in suspended environment for growth procedure to occur.

Selection of Cell Lines

There are thousands of cell lines developed from various laboratories across the globe. However, some factors need to be considered while selecting them. Some of the factors have been described below.

• Species

Generally non-human cell lines have less risk of biohazards and therefore they are preferred. However, differences in species should be taken into account while extrapolating the data to humans.

• Normal or Transformed Cells

Transformed cells are preferred as they are immortalized and expand rapidly.

• Finite or Continuous Cell Lines

Cultures with continuous cell lines are more preferred as they grow faster than finite cell lines and are easy to clone and maintain. Further they deliver higher yield. However, it is doubtful whether the continuous cell lines express the appropriate and correct functions of the cells. This is why several workers suggest to use finite cell lines though they are difficult to use.

• Growth Characteristics

Several growth parameters need to be considered while selecting cell lines such as -

1. Ability to grow in suspension
2. Population doubling time

• Cloning efficiency

1. Saturation density

• Availability

The ready availability of cell lines is much more important as sometimes it is necessary to generate cell lines in laboratory as well.

• Phenotypic Expression

It is most important that cell lines will possess cells with correct type of phenotypic expression.

Factors to be Considered for the Replacement of Medium

For the maintenance of cell lines in culture, periodic change of the medium is necessary, whether cells are proliferating or non-proliferating. The medium needs to be changes frequently for proliferating cells than that of non-proliferating cells. The rate of metabolism and cell growth will decide the time interval of changing the medium. Several factors need to be considered while changing the medium such as

• Cell Concentration

The cell cultures with high cell concentration uses the nutrients in the medium quicker than those with low concentration. Therefore the medium is needed to be changed more frequently than former.

• Decrease in pH

Decrease in the pH is the indication to change the medium. Most of the cells grow when the pH is at 7.0 and they generally stop growing when pH falls down to 6.5. The cells are likely to lose their viability with further drop in pH. The rate of fall is calculated for each cell line with chosen medium.

• Morphological Changes

Frequent examination of cell morphology is very important in culture techniques. Any deterioration in cell morphology might result in irreversible damage to cells. To avoid complete risk of cell damage, the medium needs to be changed completely.

• Cell Type

Transformed cells, continuous cell lines and embryonic cells grow rapidly and needs more frequent sub-culturing and change of medium. This is totally opposite to normal cells, which grow comparatively slow.

Conclusion

The development and different other aspects of primary culture have been covered in this article. Cell line refers to the propagation of culture after the first subculture. Once the primary culture is sub-cultured, it becomes a cell line. A provided cell line contains cell lineages of either same or distinct phenotypes.

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Created on Sep 3rd 2018 07:17. Viewed 688 times.

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