By: Annie Hu
One of the most fundamental skills for biological research is understanding how to culture cells. At its core, cell culture provides scientists with the ability to grow and observe cells of many types in an artificial environment outside of the organism that can be easily controlled and changed. Testing cells in a controlled environment free of variations provides a useful model for studying cellular processes and cell morphology, physiology, and biochemistry. This has huge implications, as cell culture provides a medium for scientists to test the effects of drugs and compounds on human cells, and develop novel medical treatments. Since cells are essentially the building blocks of life, cell culture provides many research opportunities to be excited about!
Cell culture usually begins with acquisition of the cells by obtaining cells from an organism. This can be done directly by taking pieces of the tissue and then putting these pieces into a culture that produces the desired cells (this is known as explant culture). Or, cells can also be separated from soft tissue by enzymatic reactions (most normally using the enzymes trypsin and proname) and grown in a culture. Since these cells are closest to the time of removal from the actual tissue, this first culture is commonly known as the primary culture. Primary culture persists until after the substrate it is grown on is completely or close to completely populated with cells. This is called “reaching confluence.” Cell culture doesn’t stop there: after reaching confluence, the cells are typically passaged into a new subculture with fresh media so they can continue to grow.
This first subculture is referred to as a cell line. These cell lines generally have a more limited life span and are termed finite (cell lines which acquire the ability to keep dividing are termed continuous), and during this stage certain phenotypes become more prominent because certain cells will be more favorable in terms of growth and reproduction. If you remember natural selection from biology, this process is similar! Cell lines can become what is known as cell strains if a cell line is taken from the culture by certain methods like cloning.
So now that we understand the process cells undergo, from primary culture to cell lines and to cell strains, what is it actually like for a cell to live in a culture? Normally, their culture environment will consist of a vessel, and within that vessel some sort of growth medium or substrate. The growth medium or substrate provides vital nutrients to the cells, essentially feeding the cells valuable resources like vitamins, minerals, and amino acids. Usually the environment must be regulated according to the type of cells being grown in order to somewhat mimic the naturally occurring environment that the cells would have grown and divided in before they were extracted. Some cells, called anchorage-dependent cells, grow attached to a solid/semi-solid substrate, while others might be able to survive and be grown floating in a growth medium (suspension culture). There are three types of cells that are typically cultured, characterized by their morphology. Fibroblastic cells are elongated cells which are anchorage dependent, Epithelial-like cells are polygonal and grow in patches, and are also anchorage dependent, and lastly Lymphoblast-like cells are spherical and usually grown in suspension culture. Cultured cells can also be stored for later use by cryopreservation, where they are treated with certain protective substances and then stored at very cold temperatures, to be preserved.
The process of cellular culture is certainly very intriguing! After all, being able to grow the most fundamental biological structure of the human body is no small feat. It requires many steps and a fundamental knowledge of the procedure, important terms, and other information relating to culture. These techniques can be applied to almost any area of biological science, as cells remain the source of many of the great questions in modern science and may hold the key to answering them.
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Citations:
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What Did You Learn?
Questions:
1. Why is cell culture important?
Cell culture provides a means to observe cells outside of the actual organisms, in a controlled, in vitro environment. The controlled environment creates a culture that can serve as a model for scientists studying cellular processes and testing medical treatments. The experimental benefit of having cell cultures is that it facilitates many studies conducted into observing or testing specific aspects like cell morphology, and interactions in a more favorable and simpler way.
2. What are typical culture conditions?
Cells are grown in vessels on a substrate or in a growth medium. These substrates or growth mediums provide the nutrients needed for the cells to carry out cellular processes necessary for cell life and replication. Environmental conditions like pH and temperature will vary from cell type to cell type, and as a general rule of thumb, the artificial culture environment should be close to that of the normal cellular matrix (the cell’s environment) to promote cell growth. There are also different types of cultures including anchorage dependent and suspension culture.