ok, so you're reading the newspaper, or you're watching the news and they're talking about some new medical technology, some breakthrough treating congestive heart failure or regrowing muscle tissue in wounded soldiers. i bet you that that story is going to mention that this new type of therapy uses stem cells. and i bet you, like most people, are going to listen along and just go [nods agreeably] without actually knowing what stem cells are, because who has time to know what stem cells are?!? today, we are making time. you have lots of different types of cells in your body. you've got muscle cells, and skin cells, and liver cells, and brain cells,
most of these cells have to be replaced every once in a while. your tastebuds, for instance, are replaced every 10 days or so, skin cells are replaced every couple of weeks, and liver cells turn over every 300-500 days. the cells that are doing the replacing of the old cells, and the repairing of the damaged tissue are adult stem cells, also called somatic stem cells. the different sort of cells, skin cells, liver cells, retina cells,muscle cells and intestine cells, they all have very specific jobs and they're built in very specific ways to do those jobs. different shapes, sizes, contents, mean you can't just stick a muscle cell into adamaged liver an expect it to start breaking down your alcohol for you. somatic stem cells, on the other handhaven't decided what the heck they're gonna be. they're undifferentiated. they haven'tspecialized yet.
like a college freshman, or, let's face it, a recent collegegraduate. they have no idea what they're going to do with their lives. but just like there are different types of college graduates, there are different types of adultstem cells. some can become more different kinds of things thanothers. pluripotent adult stem cells can become many different types of cells all overthe body, however, they're really hard to track down because there are so few ofthem in each organ or tissue. there also multipotent adult stem cells which are more common in the body, but restricted in the kind of cell they can become it is kinda like the difference between graduating from trade school where you have been trained to do a few different possible jobs and graduating with a degree in philosophy or something
equally unprepared for all jobs so yeah , stick a pluripotent cell in a damaged liver and it just happily becomes a liver cell pretty cool but there are some even better types of stem cells to be had embryonic stem cells which are also pluripotent these are the cells inside a human embryo when it is a blastocyst basically just a tiny nugget of human cells four or five days old
which is destroyed in the process of removing the stem cells from inside it these embryonic cells are obtained from in vitro fertilization clinics that fertilize eggs outside of the mother's body for couples who are having trouble conceiving naturally, these clinics have some left over fertilized eggs so with the donor's permission they are given to scientists doing stem cell research now the main advantage of the embryonic stem cells is that while adult stem cells can be grown in culture for time meaning they can be made to multiply over and over in a nutrient solution they can't grow as long or as fast as the embryonic stem cells
which can be maintained indefinitely into the right conditions after just six months in culture , a single wad of 30 embryonic stem cells will have yielded millions of stem cells which can go on to develop pretty much into any type of cell in the body also adult stem cells if used in some sorts of transplant therapies are more likely to be rejected than embryonic stem cells stem cell research is currently pretty hopin embryonic stem cells are being used by researchers all over the world to figure out how to repair or replace damaged cells and organs and create new drugs but regulations have taken their toll there are only about thirty five stem cell lines or families of identical pluripotent stem cells that are available for federally funded research in america
whereas europe has a couple thousand so there , now you never have to " nod along " your way through another news report about stem cells again thanks for watching this episode of scishow if you have any questions , comments or suggestions you can find us on facebook and twitter or of course down in the comments below and if you wanna keep getting smarter with us here in scishow you can go to youtube.com/scishow and subscribe transcription by dr.a
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