By: Dr. Chelsea Hughes, Ph.D., MS, T32 Postdoctoral Associate
Let’s make a cell line!
Every day at work, the first thing I do in the lab is cross my fingers and look through a microscope.
Normally, looking through a microscope would not be a particularly exciting task for me: for the past decade of my life, I have probably spent most of my days peering through a microscope. These days, however, this task has become extra special because I am trying to create cell lines from three unique populations of Atlantic killifish, Fundulus heteroclitus. Despite belonging to the same species, populations of these killifish have adapted to survive different environmental pollutants. To better understand the molecular tools that different populations use, I am trying to create a cell line from each of these populations.
What is a cell line?
A cell line is a population of cells that are clones of one another. They can be kept in the lab for a long time while retaining specific characteristics and functions.
Why create a cell line?
Studying organisms like fish can help us understand how different organs, such as kidneys, react to environmental contaminants. Organismal research (studying impacts on individual organisms) is also important because it allows us to study how fish in the embryo stage may be affected by contaminants that lead to later life consequences in adults. It also helps us understand how specific cells respond to stressors and what molecular strategies they use to overcome this stress.
Cell lines help us understand even more about the impacts of stress and especially those that cannot be easily answered when studying individual fish. For starters, they “cut out the noise” that can occur when studying organisms. Organs are made of multiple cell types that behave to stressors differently, so when we study organs, we’re actually studying how many cells respond to a stressor together. While it’s critical to understand how different cells work together to survive, one cell type can respond poorly to a stressor while others do not, and the response of the “poor responders” can drown out the beneficial response of the “good responders.” Cell lines represent a single cell type, allowing us to have a clearer picture of specific good or poor stress responses on the molecular level. Cell lines often start from a single cell and are clones of one another. Even though cell lines can accrue mutations over time, this means that these cells are genetically similar and therefore should have similar responses to stressors.
Fish cell lines and how those cells respond to stress can be easily compared to human cell lines. Fish and humans have very similar molecular toolkits to respond to stressors, but we often use these toolkits differently. We can perform the exact same experiments on both human and killifish cells, such as exposing both types of cells to the same pollutant and comparing the responses of each cell type. Comparing the responses allows us to directly compare strategies of tolerance. My hope is that understanding how adapted species effectively use their toolkits will inform treatment strategies for susceptible organisms, like us!
Why am I crossing my fingers every time I look under the microscope?
It can take a lot of work and time to make a cell line. An ideal cell line consistently grows well, maintains its characteristics over time, and has undergone a process called immortalization. Immortalization is a process by which cells gain the ability to divide indefinitely, which allows researchers to have a reusable cellular tool for years. However, spontaneous immortalization is a rare event, and, even if it occurs, there is no guarantee that the resulting cell line will survive and grow consistently over time.
After extracting embryonic killifish tissue, it took 88 days for my cells to propagate enough to be transferred to their next cell dish. For months, I have been propagating these cells in the hopes of selecting a single cell and creating a cell line from it. A mistake, such as an accidental contamination, would mean losing these killifish cells after almost six months of hard work. Each time I look through my microscope, I am hoping that months of patience, hard work, and careful bench practices have enabled my killifish cells to be healthy and grow. So if you’re reading this, cross your fingers for me: I’m probably doing the same thing as I look through the microscope.
