What all sources are there for stem cells

I have heard that there are other ways to get stem cells aside from embryos. What other sources are there?

Can one embryo provide cells that replicate and provide enough cells for everyone or do you need to keep finding new sources?

The stem cells that you can make from embryos are totipotent, meaning that they have the potential to turn into any cell type in the body. You aren’t carrying any of those around with you, but in your body’s tissues are pluripotent stem cells specific to each tissue type, which can make a bunch of different related sorts of cells. For example, in your bone marrow, you’ve got stem cells that can turn into a bunch of different types of blood cells, but not into, let’s say, liver cells.

As someone who has done research with these, let me tell you that, despite everyone’s fondest wishes, “one of these things is not like the other.”

In my lab we were using pluripotent stem cells to try to do something that really required totipotent stem cells, and it was a complete mess. For example, bone kept showing up in the wrong places, because the only stem cells we could easily harvest were from connective tissue, and boy did it really want to become the connective tissue of its own choice.

So “stem cells” is a much misunderstood term, and although I think we’d all love to find a substitute for ebryonic stem cells, there just isn’t any such thing that we’ve identified.

As far as one embryo being enough, the answer is that cell lines wear out. Just like the cells in your body that decline in function as you get older and in some cases stop completely (for example the ones that make melanin to color your hair) cells in a dish can only replicate so many times. This is caused by a lot of things, but they are particularly limited by a little stutter step that happens at the end of each DNA chain every time it’s replicated, causing part of it to get chopped off. You only have so many buffer sequences, called telomeres, to lose before the code itself gets chopped away. Interestingly, some cancer cells can add on new telomeres, while normal human cells cannot - that’s why cancer cell replication is or at least seems to be unlimited. Some species get around this by having circular DNA!

There are a few “human” cell lines that have lasted for decades (you can look up “HELA cells”) but there’s much debate as to how human they really are at this point, and I personally wouldn’t want anyone transplanting them into my body. They’ve been heavily contaminated over time with other things (of course, thanks to viruses, so have we, but that’s for another thread).

Your questions make me think that you’re trying to come up with a good way around a thorny problem, and I, for one, really appreciate your thoughfulness. Keep trying! If we can figure this one out we’ll all be better off for it.

I have heard about stem cells being harvested from the umbilical cord.
Research on Umbilical Cord Matrix

And on NPR the other day (which is available on podcast or can be streamed from NPR.org), there was a story about how babies give mothers defensive stem cells that have repaired livers and cured mothers of various illnesses. It’s worth a listen/read.

Babies Give Cells to Mothers.

There is also research being done into harvesting stem cells from piggies, particularly in finding a cure for diabetes. I would assume the ratio of donor:recipient would remain about the same, but given the the donors would be pigs, we’re likely to have better success finding donors…

Sorry to resurrect an old thread, but I learned something new and thought I’d share:

http://www.newscientist.com/article.ns?id=dn3643

Looks like teeth are a source of stem cells.

But aren’t the HELA cells originally from a cancerous tumor? As you already mentioned, cancer cells don’t seem to “age” in the same way as healthy cells.

Reading over the article The Controvert linked, it looks like the tooth cells are more versatile than most adult stem cells, but still not as much as embryonic ones. So the debate isn’t exactly moot, yet.