January 25, 2025

Cell Culturing

Cell lines are a series of cell cultures that have been through many passages, movements from one culture to another, to the point of which the cells are a homogenous population. To conduct a proper passage, one must use a sterile hood to avoid bacterial contamination. In this case, it was a passage for 4T1 cells, mammary breast tumor cells from mice. After adding trypsin, which allows the cells to detach from the flask, the culture was incubated and then the cells were resuspended in fresh culture media, specifically RPMI media. The RPMI media inactivates the trypsin and contains serum proteins. Then the tube of cells was centrifuged for five minutes at 500 rcf. After centrifuging,  the supernatant was discarded and the cells were resuspended in media. The culture was then added to a new flask, carefully avoiding the neck of the flask to avoid bacterial growth and returned to the incubator in order to return to 100% confluency, which is the percentage of a cell culture surface that is covered in cell growth. Proper sterile procedure is essential to a well-run experiment. If the media or flasks were ever opened outside of the sterile hood, there was a chance of contaminating the culture. Sterility was ensured by spraying everything with ethanol and purifying the hood with UV light.