Cell Culture: Videos & Practice Problems

Cell culture is the process of growing cells in a laboratory, initiated in 1907. There are two main types: primary cultures, derived directly from tissues, and secondary cultures, which are cell lines that can grow indefinitely due to genetic modifications. These cultures require specific nutrients, temperature, and gas exchange to thrive. Research using cell cultures is often referred to as in vitro, while some biochemists may call it in vivo. This method allows for the study of cellular processes in a controlled environment, making it essential for various scientific investigations.

Cell Culture

Hi. In this video, I'm going to be talking to you about cell culture. So what cell culture is the process of growing cells in a laboratory setting. This began in 1907, and there are really two types of cultures that cells can be grown in. The first is called a primary culture, and these are cells directly taken from tissue. So you have some type of tissue, skin tissue, a kidney, a brain, whatever. And you begin to dissect that tissue. You take apart the extracellular matrix. You cut the tissue into extremely thin slices, and then you can extract those cells from those thin slices and actually grow them in a laboratory. Now, you can imagine all of that processing is really harsh on these cells that aren't used to stuff like that. And so these cells, although very useful because they come directly out of individuals, are hard to work with because they don't live that long, and they're really difficult to keep alive in a culture setting. So what researchers have done is created these secondary cultures, and these are cells that are derived from other culture cells. So if you can keep these primary culture tissue cells alive long enough so that they can divide, then you can continue dividing those cultures if they're properly processed to create these cell lines. Now cell lines are cells that have undergone some type of genetic modification either by themselves or something a scientist has done to them. And this allows them to grow indefinitely. So can you think of maybe diseases for instance that cell lines could come from? Can you think of any disease that is the result of cells growing indefinitely? Right. This sounds exactly like cancer. Right? So cancer is, you know, just uncontrolled cell growth essentially and division. And so cell lines are often derived from cancer cells, or scientists have taken cells that aren't cancer cells and mutated them so that they can grow indefinitely. And generally, if you were to put these cells into a special type of laboratory mice, they would typically grow tumors. But, although these can be grown indefinitely, they are cells, and so cells don't live forever. Right? So they usually die after about 25 to 40 divisions. And you say okay well, then why do you put that much time into creating these cell lines? Well, the reason is that when you have a cell line and it divides, and it divides a couple of times, then you have a ton of cells. I mean, you cannot deplete a flask of cells after just a couple of divisions. And so, you take those early dividing cells, the cells that only have a couple of divisions, and you can freeze them. You can freeze them at minus 80 degrees Celsius, you can freeze them in liquid nitrogen, and you can keep them essentially in liquid nitrogen forever. And when you thaw those cells anytime a year later, 10 years later, or 50 years later, they will just start dividing as they did before. So cell lines are super useful because you can have these cell lines that you freeze and then just use when you need them. But growing cells require because cells require a lot of care when grown in a laboratory. They have to have nutrients they would normally get in the body. Right? And so we provide that through some type of media solution. They have to be grown usually on some type of flat dish or in a 3D environment that has like a fake extracellular matrix in it. And they also have to be maintained at body temperature and with certain gas exchanges. You don't really think about it. We breathe in oxygen and exhale carbon dioxide. Well, the cells need those gases. So whenever you're growing these cells in a laboratory, you have to facilitate that gas process. But it's all worth it. All the care that they take is entirely worth it because, this provides a single cell population to work with, which makes doing it much easier. And it's so convenient, you know, you don't need a hundred million individuals, you just need a hundred million cells. And that can be grown in a single dish, and you can have so much more than that grown in a dish, and it's so easy to do, so it's really convenient. But one of the confusing things about it is that research using cell culture is called different things depending on who you talk to. So the majority of people call cell culture in vitro research because this means that it's not happening in a living organism. I mean, we're not dealing with rats, we're not dealing with mice, we're not dealing with humans. So this is in vitro because it's happening essentially in a plastic dish. But if you talk to some people, especially biochemists who like to do things in tubes, biochemists typically call this in vivo because cells are living. So the experiments you do with cells are in living cells, so they call it in vivo. Now, which one should you call it? I mean, I can give you my preference. My preference is in vitro, but you should probably ask your professor or go with what your book does because you don't want to miss a question or something just because of this misunderstanding. So let me back out of the way. Typically, when you grow cells in culture, you grow them in some kind of dishes like these. And you can see this red stuff here is the media. So that's providing the nutrients to the cells, which are growing, you know, on this very bottom plastic layer of this dish. Now, if you were to zoom in, what the cells would look like is this. Now, these have been stained with something that makes their nucleus blue, so they wouldn't normally look blue. If you look at the rest of the cells, so this outside part here, outside of the blue, this is what cells really look like when you look at them under a microscope. They are transparent, you can see some structures, but I mean, unless you really know what you're looking for, you're not going to know what these are. But this is what cells look like, and scientists use these cultures to study a lot of different cellular processes. So with that, let's now move on.

Which cell types are derived from primary tissue?

• A. Primary cell cultures
• B. Secondary cell cultures
• C. Tertiary cell cultures
• D. Cell lines

Answer: (A)

In vitro can describe experiments happening in all but which of the following?

• A. In a tube
• B. In cells
• C. In living organisms

Answer: (C)

Here’s what students ask on this topic:

What is cell culture and why is it important in scientific research?

Cell culture is the process of growing cells in a controlled laboratory environment. It began in 1907 and involves two main types: primary cultures, derived directly from tissues, and secondary cultures, which are cell lines that can grow indefinitely due to genetic modifications. Cell culture is crucial in scientific research because it allows for the study of cellular processes in a controlled setting. This method provides a consistent and reproducible environment to investigate cell behavior, drug responses, and disease mechanisms, making it essential for advancements in medical and biological research.

What are the differences between primary and secondary cell cultures?

Primary cell cultures are derived directly from tissues, such as skin or kidney, and involve dissecting the tissue to extract cells. These cells are challenging to maintain as they do not live long in culture. Secondary cell cultures, or cell lines, are derived from primary cultures and have undergone genetic modifications to grow indefinitely. These modifications often involve mutations that allow continuous cell division. While primary cultures provide cells that closely resemble those in the body, secondary cultures offer a more sustainable and convenient option for long-term studies.

How are cell lines created and maintained in the laboratory?

Cell lines are created by taking primary culture cells and inducing genetic modifications that allow them to grow indefinitely. This can occur naturally, as in cancer cells, or be induced by scientists. Once established, cell lines are maintained by providing essential nutrients through a media solution, ensuring proper temperature and gas exchange, and growing them on flat dishes or 3D environments. Early dividing cells can be frozen at -80°C or in liquid nitrogen for long-term storage. When thawed, these cells resume dividing, making cell lines a valuable resource for research.

What are the common challenges faced in cell culture?

Common challenges in cell culture include maintaining cell viability, preventing contamination, and providing the correct environment for growth. Cells require specific nutrients, temperature, and gas exchange to thrive, which can be difficult to consistently manage. Contamination from bacteria, fungi, or other cell lines can compromise experiments. Additionally, primary cultures are particularly challenging as they do not live long and are sensitive to the harsh processing required for extraction. Despite these challenges, cell culture remains a vital tool in scientific research due to its ability to provide a controlled environment for studying cellular processes.

What is the difference between in vitro and in vivo research in the context of cell culture?

In the context of cell culture, in vitro research refers to experiments conducted outside of a living organism, typically in a plastic dish or tube. This term is widely used because the cells are grown in a controlled laboratory environment rather than within a living body. In contrast, in vivo research involves studying processes within living organisms, such as animals or humans. Some biochemists may refer to cell culture as in vivo because the cells are living, but the majority of researchers prefer the term in vitro to distinguish it from whole-organism studies.