Contamination of Your Cell Culture

The most common and widespread issue with cultures is the potential for loss due to contamination. Nearly every culture laboratory has experienced the loss of cell cultures at some point or another and understand how frustrating it can be after having put hours of work into creating and maintaining viable cultures. Culture contamination comes in various types, but always has an adverse effect on the quality of the cell, as well as the research conducted. Whether the contamination is seen or unseen, chemical or biological or seemingly harmless or overtly destructive, it is always exasperating.

There are three classes of contamination: Minor irritations, when up to cells are intermittently lost due to contamination; serious crisis, when the frequency of loss increases due to contamination, and in some instances, entire experiments are ruined; and lastly major devastation, where contamination calls the validity of the current or past work into question.

Cell culture contamination is any nonliving substance that causes undesirable and adverse effects. It is important to note that even essential nutrients can become contaminants in high doses, making it difficult to avoid unwanted changes.

The cell culture media is often responsible for chemical contamination because of the reagents, water and additives used to make and supplement them. Because of this, only the purest and highest quality reagents should be used, and proper storage to prevent deterioration employed. Evaluation by the researcher or supplier certification is essential to ensuring the highest quality is being used. There are several other possible contaminants that pose a threat such as metal ions, endotoxins, plasticizers, free radicals and germ residues to name a few.

Though it has always been the dream of scientists and researchers to eradicate all potential for cell culture contamination, it is a highly unlikely and generally unattainable goal. Contamination cannot be completely eliminated, but the frequency and severity of it can be managed effectively, helping to preserve and protect the valuable cultures as well as the time put into the experiment.

If you do encounter contamination of your culture there are some basic steps you can take. The ideal scenario is to remove those culture from incubation, bleach them and start with fresh cells, media and reagents. If you are working with cultures which are irreplaceable you can treat with a course of antibiotics to see if that resolves the contamination. This can be monitored but media turbidity, pH and growth rate as basic monitoring tests.

As always with a contamination, be sure to check all your media, reagents, sera and supplement stocks as the possible source and thoroughly clean your incubator and hood to prevent spreading to other cultures.

As a preventative measure, routinely screen your cell lines for lentivirus, mycoplasma and other viruses or bacteria. Although in some cases these will not drastically alter the growth rate of your cells, they may alter your results. Reproducibility is vital to publication so this is a must for all cell culture users. These contaminants can be screen for with a simple over the counter PCR kit available from most life science companies and only requires media from a near confluent flask.