In the Cell and Molecular Biology course that I took during my second year, we learned how to maintain adherent mammalian cells in the lab. Cell Culture is used in biology to study how cells grow under controlled conditions. Since this is not a widely known topic, I will start off with defining and explaining some of the common terminology.
- Culture Flask – transparent rectangular container in which cells grow.
- Pipette – dispensing specific volumes of liquid.
- Adherent cells – cells that grow by attaching themselves to the bottom of the flask.
- Media – liquid that cells grow in that provide nutrients.
- Confluence – state in which cells are spread completely across and covered the bottom of the flask.
- Passaging – process of removing cells from a flask and moving a portion of those cells to a new flask to glow until confluency.
The cells we used in our class were derived from hamster ovaries and made into immortalized cell lines which means that the cells have been mutated to proliferate indefinitely. Our lab instructor started our first flask of cells for us, then each student was responsible for keeping their line of cells healthy.
Passing Cells:
When the cells in a flask have reached nearly complete confluency, they should be passed to a new flask. The first step is to remove the old media from the flask with a pipette. Next, the cells must be “rinsed” with a buffer solution to rid the cells of leftover ions from the media that can cause the cells to stick together. Now the cells have to be treated with an cleaving enzyme called trypsin. This soaks on the layer of cells for several minutes and breaks the protein bonds the cells made to attach themselves to the bottom of the flask. Once the cells are visibly detached from the surface, a small volume of media is added to the flask to deactivate the trypsin. Then, depending on the density of cells desired, remove the necessary amount of cell solution from the flask and place in a new flask with media. The flask should be placed in an incubator set at 37 degrees Celsius with a flow of carbon dioxide. After a few hours, the cells will attach to the bottom of the flask and begin to proliferate. Within the next few days, the cells will grow, spreading throughout the bottom of the flask. It is important that the cells do not reach complete confluency before they are passed again. If this happens the cells may grow on top of each other or start to die off. An improvement that would be extremely beneficial would be a flask that could recognize when the cells are close to becoming confluent. If there was an LED light implemented on the flask and could signal when the flask was almost ready to be passed, that would save researchers from checking their flasks everyday.
Leah Felker
Technical Writing and Editing 