In a cell culture laboratory, any foreign components or component changes in the cell culture system should be regarded as contamination. Cell contamination cannot be completely eliminated, but it can reduce the frequency of its occurrence and the severity of its consequences. Cell contamination can mainly be classified into physical, chemical and biological contamination based on the source of pollution.

(1) Physical pollution

Physical contamination affects the metabolism of cells by influencing the biochemical components in the cell culture system. For instance, temperature, radiation, vibration, and radiation (ultraviolet rays or fluorescence) can all have an impact on cells. Common examples include: the temperature of the incubator being too high, placing equipment that can cause mechanical vibration around it, and reagents being placed in a refrigerator with a glass door and exposed to light for a long time, etc. Physical pollution is often overlooked by people or generally classified as chemical pollution.

(2) Chemical pollution

Many chemical substances in the culture environment can cause contamination of cells. Chemical substances are not always the driving force for the growth of YZ cells. Some chemical substances, such as hormones, can promote cell growth. Unpurified substances, reagents, water, serum, growth cofactors and containers for storing reagents can all be sources of chemical contamination. To prevent the contamination of water by substances such as metal ions, organic molecules, and intracellular toxins, ultrapure water free of impurities must be used when preparing liquids and cleaning containers. All substances used in cell culture should be of high purity and have been identified by authoritative institutions. The experimenter himself should also conduct purity identification on the above components. At the same time, it is also very important to correctly prepare and store the culture medium and reagents. Standard operating procedures should be adopted to avoid errors such as incorrect calculation of liquid volume and the mixed use of similar compounds.

(3) Microbial contamination

The causes of microbial contamination can be divided into two stages: the experimental preparation stage and the experimental operation process. The reasons for the preparation stage include: incomplete sterilization of experimental consumables; The cleanliness of the cell room is insufficient, increasing the risk of microbial contamination. The cleanliness of the laminar flow hood is insufficient, the disinfection is not thorough enough, the ultraviolet rays are not pre-exposed for a sufficient period of time, and the surface is not wiped with alcohol. Not wearing sterile latex gloves; The reagent itself has been contaminated and has not been detected. Contamination in experimental operations is often caused by lack of strictness and carelessness, such as passing hands over sterile reagents. Improper operation of the pipette caused the liquid to come into contact with the front end of the pipette. The pipette sucked the liquid too vigorously; The gun tip has not been replaced, and there is poor contamination, etc.

(4) Cross-contamination of cells

Cell contamination is different from bacterial contamination. Cell contamination occurs when various cells are cultured simultaneously and the equipment or liquids used are mixed. This kind of pollution has no microorganisms present, but it causes confusion among different types of cultured cells, and changes in cell growth characteristics and morphology. The contaminated cells cannot be used for experimental research due to impure types.