tisiwoota

1. Read this post, by some twisted wacko whom you probably shouldn’t trust with your pet monkey.

{1a. Optional background on the chimera experiments/issues.}

2. Now you’re ready to be updated on something I randomly stumbled across [well, if by ‘randomly’, you mean ‘by clicking the amazing filter-blog I check everysingleday’… but the timing of this topic turning up is quite a random coincidence…]:

It turns out the response of stem-cells to their microenvironment [a factor I vaguely speculated about in my comments to #1] is a hot topic right now.

Check this out:
“Some researchers argue that providing an appropriate three-dimensional environment in which signals come from the right direction will matter as much as using the right biochemicals.”

Of course embryonic stem cells are likely to be less picky about things than adult stem cells, but even so…

“Just injecting embryonic stem cells is probably not the way to go… Left to their own devices, they do their own thing and go in different directions.”

On the other hand, it seems that stem-cells themselves aren’t just helpless direction-following slaves:

“…Gage’s group has also found that mammalian neural stem cells are not such passive players in their microenvironment as the fruitfly germline stem cells studied by Spradling and Fuller. Andrew Wurmser, a postdoc in Gage’s lab, has found that neural stem cells can, under certain conditions, give rise to endothelial cells. This hints that, if the need arises, they may be able to populate their microenvironment with the support cells that they need to thrive.

Researchers led by Elaine Fuchs of Rockefeller University in New York have added further weight to the idea that some stem cells can create their own microenvironments. She has isolated individual epithelial stem cells, which give rise to skin and hair, and cultured them in the lab. When she subsequently grafted cells from these cultures into the skin of mutant hairless mice, they gave rise to hair follicles containing stem cells and support cells. The nude mice grew tufts of hair.”

…

So… What to conclude? It does seem that stem-cells are tricky enough that merely injecting human stem-cells into an animal brain probably won’t give them a substantially human-acting brain (as in fully sentient/conscious)– but could perhaps lead to something just human enough to make us morally uncomfortable. [Then again, as the article points out, in the wrong environment stem-cells can be wiped out or turn cancerous– The survival of the small sample injected in Weissman’s initial experiment doesn’t necessarily indicate that total replacement would even create a functional whole…]

Wow, what a dizzying topic…