Cell Culture

Today at my internship I learned how to grow cells in culture! First, we created a liquid medium for the cells to grow in. Our DMEM medium consists of 90% nutrients including salts, glucose, amino acid, and vitamins. The remaining 10% of the medium is growth factors, specifically, serum. Serum is very important for cell growth as it provides cells with adhesion factors, hormones and lipids and other minerals that allow the cell to grow as a confluent layer across a surface. The serum used in our medium is Fetal Bovine Serum. It is a (somewhat creepy) amber liquid that is a remnant of the coagulated blood collected from a cow  fetus. The red blood cells are taken out of the serum by centrifuge, and growth factors and a small amount of antibodies are left. 0.55 mL of antibiotics was also added to our medium, which is a key factor in inhibiting any type of contamination in the cultured cells, including bacterial, fungal, yeast, mold, and viral growth. Avoiding contamination is extremely important in keeping healthy cells alive and multiplying. To avoid any type of contamination, we worked in a ventilated hood that filtered out any pathogens in the air, wore gloves, disposed of all pipettes after a single use, and cleaned the surfaces of anything that might come into contact with the cells with isopropanol.

Next, we took a flask of growing BSC-1 cells, which are African green monkey kidney cells. These cells are epithelial cells, which grow attached to a substrate. Our goal was to split these cells into two flasks, and in order to do so, we needed to get them off the surface of the flask which they were growing on. We did this by adding a solution known as Trypsin which is a protease that essentially eats away at the cell membranes, thus making them weak and unable to hold onto the surface. They were only exposed to the solution for a few seconds, as we did not want to damage the cells beyond repair. The suspended cells were round and more mobile compared to the initial cells that were growing on the surface of the flask. The initial cells were a mixture of round and long, football-shaped cells.

We then added the medium, and split the cells into two flasks. As they begin to grow and spread out as a layer on the bottom of the flask, they start to resemble tiny islands floating in the pink solution of the medium. My internship (sadly) only lasts three hours, so I will not be able to see the cells grow into a confluent layer until next time. However, as I checked on my cells every 20 minutes, I began to see them grow into these tiny clusters. We stored our BSC-1 cells in an incubator that is set at 37 degrees Celsius- about body temperature. The cells are kept in a humid environment, with 5% carbon-dioxide. The carbon-dioxide acts as a buffer zone that keeps the pH of the cell cultures at a healthy level- about pH 7.4.