What are the main sources of cell contamination?

Any components that are harmful to cell survival in a cell culture environment and foreign substances that cause cellular purity should be considered contaminated, and cell contamination cannot be completely eliminated, but can reduce the frequency and severity of its consequences.
cell pollution according to the source of pollution can be divided into physical, chemical and biological pollution.
sources, hazards and prevention of physical pollution: physical pollution is often ignored or generally classified as chemical pollution.
physical contamination affects cell metabolism by affecting the biochemical components of the cell culture system.
factors in the cultured environment, such as temperature, radiation, vibration, radiation (ultraviolet or fluorescence), affect cells.
cells, culture fluids, or other culture reagents exposed to radiation, radiation, or overheated temperatures can cause changes in cell metabolism, such as cell synchronization, inhibited cell growth, and even cell death.
can reduce the influence of physical factors in the environment on cells through the rational design of laboratories and the establishment of standardized operating procedures.
incubators should be placed in a more constant temperature environment, surrounded by equipment that can cause mechanical vibration, such as centrifders.
culture fluids and culture reagents should be placed in a fixed position, in order to avoid lighting reagents can not be placed in the glass door of the refrigerator, reagents around the isotopes can not be placed.
the culture solution is removed from the refrigerator and placed at room temperature for a period of time before conducting experiments to avoid the effects of too cold temperature on cells.
sources, hazards and preventions of chemical contamination: many chemicals in the cultured environment can cause cell contamination.
chemicals do not always inhibit cell growth, and certain chemicals, such as hormones, promote cell growth.
different cells react differently to chemical contamination.
, reagents, water, serums, cofactors and containers for storing reagents can all be sources of chemical contamination.
essential nutrients for cell culture, such as amino acids, can also be toxic to cells if the concentration exceeds the appropriate range.
, the requirements for serums and buffers are different under the optimal culture conditions of different cell lineages and should be strictly controlled in culture.
denatured agents or soaps (usually on the inner surface of the cap) that remain during cleaning of glass products are the most common chemical contamination.
water is the only compound that expands when solidified.
this factor should therefore be taken into account when selecting containers for frozen cells.
the rupture of the container due to the expansion of water is an important cause of reagent contamination.
in order to avoid contamination of water by metal ions, organic molecules, endotoxins and other substances, ultra-pure water without impurities must be used in the preparation of liquids and cleaning containers.
note that ultra-pure water is placed too long and its purity decreases.
water is often contaminated during high-pressure vapor sterilization and distilled water, as there may be a small amount of chemical residue after routine maintenance of high-pressure steam pans and pure water machines.
to ensure the purity of water, we should take measures to avoid chemical residues.
animal serum is a natural medium commonly used in cell culture, but serum is also a potential source of biological and chemical contamination.
because the serum is collected in multiple animals, and the production process and quality of different manufacturers are different, so the concentration of many components in the serum there is a great variation.
's ability to grow and toxic side effects on different cells depend on factors such as their differentiation function, tissue sources, and the composition of the culture.
in a series of experiments, in order to ensure the repeatability of the experiment, it is best to choose the same batch of serum.
, culture additional ingredients, reagent culture fluids, culture additional ingredients, reagents may become a source of chemical contamination.
substances used in cell culture should be high purity, and after the identification of authoritative institutions, the experimenter himself should also be the above-mentioned components of purity identification.
the same time, it is also very important to properly configure and store culture fluids and reagents, and standard operating steps should be taken to avoid errors in liquid volume calculation and mixing similar compounds.
a variety of different petri dishes and containers are used in the process of cell culture.
size of the petri dish, the forming design may affect the pH of the gas exchange, humidity, culture fluid and cell growth density in the culture.
in the process and sterilization of the petri dish may have an impact on the culture system.
plastic products may be left with some toxic forming agents in the production process, different production processes may cause different surface adhesion capabilities of utensils.
use suitable plastic or glass containers when storing different substances, as alcohol, strong acids, and strong alkalis dissolve certain components of plastic or glass.
Microbial contamination Because in-body cultured cells themselves do not have the ability to resist pollution, and the anti-pollution capacity of antibiotics in media is also limited, so cell microbial contamination, once occurred is often irresisticable.
in the early stages of cell contamination or less contaminated, can be timely treatment and removal of contaminants, some cells may also be saved.
But when cells continue to grow in a contaminated environment, the light cells grow slowly, the division phase decreases, the cells become rough, the contours are enhanced, more particulate matter appears in the cell pulp;
effects of different microbial contaminants on cells vary, and the effects of mytrogens and viruses on cell morphology and skills in microorganisms are long-term, slow, and potential.
mold and bacteria multiply rapidly, inhibiting cell growth or producing toxic substances to kill cells in a very short period of time.
of mold contamination: many kinds of fungi, pollution is more than tritomy, white candide, yeast, black mold, spores and so on.
most of the mold pollution in the culture liquid to form a pale yellow or white floating objects, generally visible to the naked eye, more easily found, in the short term culture liquid more unchanged turbid.
inverted microscope, cells can be seen crisscrossing the silk, branch or tube-like mycelium, and floating in the culture fluid.
many strains of mycelium that can be seen in chains under a high mirror.
candid bacteria and yeast strains are egg-round and grow on and around cells.
sometimes through a microscope may find the growth of mycelium in the outer wall of the culture bottle, more easily mistaken for pollution.
found outside the bottle of mycelium should be cleaned with alcohol in a timely manner.
: First, determine whether the contaminants are bacteria, fungi, myetrogens, or yeast.
now you're sure it's mold contamination.
therefore, contaminated cells are isolated from other cell lineages as soon as possible, and the equipment and reagents used in the experiment need to be treated.
In general, high concentrations of antibiotics and antimycin may have toxic effects on cells or cell linens, and therefore dose reaction experiments are conducted to determine the dose levels at which antibiotics and antimycin are toxic.
this is especially important when using antibiotics such as methromycin B and antimycin such as terecin.
following are recommended experimental steps to determine toxicity levels and eliminate culture contamination.
1) Digest, count, and dilute cells in antibiotic-free mediums, diluting concentrations to conventional cells.
2) Disperse cell suspension into porous culture plates, or in several small culture bottles.
the selection of antibiotics into each hole within a concentration gradient.
example, the following concentrations are recommended for methromycin B, 0.25, 0.50, 1.0, 2.0, 4.0, 8.0 mg/ml.
3) Cytotoxic indicators are observed daily, such as shedding, empty bubbles, decreased convergence and rounding.
4) After determining the antibiotic toxicity level, culture cells 2-3 generations of cultured cells with antibiotics below the toxic concentration of 2-3 times the concentration.
5) Culture a generation of cells in antibiotic-free mediums.
6) Repeat step 4.
7) Culture 4-6 generations in antibiotic-free mediums to determine contamination.
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