ES cells: Where do they come from? Part Two.
As we learned last week, ES cells come from the blastocyst stage embryo. We also touched on three ways to obtain ES cells. But I stopped short of describing the actual donated tissue used to make them. So this week, we’ll briefly describe where these precious little cells come from.
First off, the in vitro fertilization (IVF) clinics. Again, I make no claims or offer up my take on the ethics involved in this. I am simply stating facts with no emotional input. There are plenty of embryos out there. Millions, even. They are being held in liquid nitrogen tanks, frozen for future use. Many couples who have a hard time making babies turn to modern medicine to help them out. And for good reason: It works. Sparing unnecessary specifics, the woman is given a regimen of hormone therapies to get her eggs to be released. Sparing more unnecessary specifics, the eggs are fertilized in vitro (in a dish) and some of the embryos are put back into the woman with the hopes that one or more will attach resulting in a pregnancy.
The others are frozen and stored if the first round does not work. Well, as we’ve seen with countless sets of twins, triplets, and the occasional sextuplets and Octomom, IVF works, sometimes better than hoped. So, if you were trying to have a baby and end up with triplets, chances are, you might reconsider having the rest of the embryos you have frozen, used to make more kids (unless, of course, you’re you-know-who or you aspire to live in a shoe). A lot of people do not want these embryos, and more importantly, most parents do not want these embryos to become someone else’s kids. Luckily, there are enough parents out there who have donated these embryos to research, with the understanding that they may very well be made into ES cells. It’s these embryos that provide the starting material for many ES cell lines.
Next up is one that has a little bit of that Hollywood yuck factor to it: Somatic Cell Nuclear Transfer (SCNT), or cloning. Yes, like Dolly the sheep. The idea is to take the nucleus of an adult cell and in Dolly’s case, it was a mammary cell, to provide all the genetic material for a new critter, or in this case, a new stem cell line. In case you’re asking (and I was when I found out about Dolly) Dolly was named after Dolly Parton. And, yes, it was done with reference (dare I say deference) to Dolly Parton’s apparently impressive mammary gland tissue. Ahh, those crazy scientists and their quirky sense of humor!
So why do this? Well, the idea is that you can take one of your own cells, find a woman who wants to donate her eggs, put your genetic material into the egg, and make a blastocyst that is genetically identical to you. Then, you don’t have to worry about your body rejecting the cells (they’re kinda your own cells, you know?). However, this approach is losing steam fast, as we now have iPS cell technology. More on that another time.
Finally, we have our third and most utilized option: Existing ES cell lines. Scientists are an altruistic bunch. They share. So, many cell lines out there have been spread across many many labs and most labs using human ES cells, are using a line (or several) that they either purchased or acquired from other labs. That’s how I got mine, and that’s how most of my friends got theirs. Yeah, I know, not too exciting and ridiculously obvious to some. But hey, I said there are three ways to get ES cells, and as lackluster as this one is, it IS the third way.
So stay tuned for next week, kids. We’ll dive into the adult stem cell world. Actually, it’s more like snorkeling where we’ll see stuff, but nothing too deep. This is summer, after all!