Gonad Quandary!!!

Well, the latest New York Times Sunday Magazine had one of the creepier articles I've read in quite some time...

It's about using human stem cells to create genetic chimeras: animals with human cells in some of their organs. The sci-fi reading side of me goes, "Ooo, cool!" when it's not actively cringing right next to my humanist side.

Some samples of the freaky genetic chimera-y goodness inside the article:

Several years ago, Zanjani and his colleagues began injecting fetal lambs with human stem cells, mostly ones derived from human bone marrow. He said he hoped that the cells would transform into blood cells so that he could use the sheep to study the human blood system. According to Zanjani, when he examined the sheep he discovered that the human cells had traveled with their lymphatic system throughout the sheep's body, developing into blood, bone, liver, heart and assorted other cells, including some in the brain. While some scientists are skeptical of his findings, Zanjani told me that some have livers that are as much as 40 percent humanized, with distinct human structural units pumping out uniquely human proteins.

While the idea of partly humanized sheep might make some people a little uncomfortable, it isn't easy to see where they trespass across some unambiguous ethical line. But according to Dr. William Hurlbut, a physician and consulting professor in human biology at Stanford, who serves with Kass on the President's Council for Bioethics, the seeing is exactly the point. What if, instead of internal human organs, Zanjani's sheep sported recognizably human parts on the outside -- human limbs or genitals, for instance, ready for transplant should the need arise? Hurlbut maintains that this is scientifically plausible. But it would be wrong. Every living thing has a natural trajectory through its life beginning at conception, and in Hurlbut's view, a visible chimera would veer dangerously off course.

''It has to do with the relationship between signs and their meaning,'' he told me. ''Human appearance is something we should reserve for humans. Anything else that looks human debases the coinage of truth.''

Um, excuse me, Dr. Hurlbut? If I may interject for a moment? Debasing the coinage of truth is the least of our ethical worries here, okay? Jeez, are you seriously saying that a sheep could have a human brain and internal organs, but as long as it still looks like a sheep, everything's okay?

Apparently, a large part of the reason the sheep do still look like sheep is that the human stem cells weren't injected until late in their fetal development, when they were already pretty definitively sheep. But there's a mad researcher who wants to try a similar experiment with highly impressionable 3-5 day old mouse embryos, which gives even genetic researchers the creeps.

Why all the shuddering? For starters, there is the gonad quandary. If the experiment really works, the human cells should differentiate into all of the embryo's cell lineages, including the one that eventually forms the animal's reproductive cells. If the mouse were male, some of its sperm might thus be human, and if it were female, some of its eggs might be human eggs. If two such creatures were to mate, there would be a chance that a human embryo could be conceived and begin to grow in a mouse uterus -- a sort of Stuart Little scenario, but in reverse and not so cute.

''Literally nobody wants to see an experiment where two mice that have eggs and sperm of human origin have the opportunity to mate and produce human offspring,'' says Dr. Norman Fost, professor of pediatrics and director of the bioethics program at the University of Wisconsin and a member of the National Academy of Sciences committee reviewing stem-cell research policies. ''That's beyond anybody's wildest nightmare.''

Gah!

More fun with mice:

...[Irving Weissman] came up with an ingenious idea: why not make a mouse with a brain composed entirely of human neurons? In theory, at least, this could be achieved by transplanting human neural stem cells into the fetal brain of a strain of mouse whose own neurons happen to die off just before birth. If the human stem cells took up the slack and differentiated along the same lines as in the earlier experiment, you might just end up with a living newborn mouse controlled by a functioning brain that just happened to be composed of human cells.

Or, if you want to really go for the creepiness home run...

''One could imagine that if you took a human embryonic midbrain and spliced it into a developing chimpanzee, you could get a chimp with many of our automatic vocalizations,'' says Terrence Deacon, a biological anthropologist at the University of California at Berkeley and a member of the Johns Hopkins committee. ''It wouldn't be able to talk. But it might laugh or sob, instead of pant-hoot.''

Thankfully, it doesn't appear that anyone has any intention of trying this. But the man-mouse is unsettling enough, even though the article claims that, in essence, the human brain cells wouldn't have enough space to grow into anything like their accustomed human capabilities, and that the fetal man-mice would be aborted and never brought to term. Somehow, that all fails to make me feel a whole lot better about the whole enterprise...

Finally, this puts me in mind of some works of fiction: One is David Brin's Uplift Trilogies, in which humans have elevated chimps and dolphins to full sentience (i.e., ability to speak and fly spaceships), much to the horror of the galactic community - not really the Uplift itself, but the fact that we bootstrapped ourselves to sentience all by ourselves, without the aid of a patron race. But for what it's worth, we Uplifted the dolphins and chimps by augmenting their existing genetic makeup, not by blending it with our own, so it's somewhat less horrific. The chimps seem a bit rough around the edges, but the sentient dolphins are rather elegant and poetic creatures who like to speak in haiku.

The other is a truly horrific Larry Fessenden (Habit, Wendigo) movie called No Telling, about a bioresearcher and his wife, who move to the country in hopes of salvaging their marriage. He does animal experiments for a pharmaceutical company, and becomes utterly obsessed with his chillingly heartless work. When his employer balks at sending him the monkeys he craves for his experiments, he begins kidnapping and buying up local animals. The movie ends with him showing off his crowning achievement - I can't really tell you what it is, but suffice it to say that this post reminded me of it, and it is possibly the most haunting and awful thing I have ever seen. If you're an animal lover and are even remotely easy to upset, do not see this movie. I'm serious. It's good, but it's terrible, if you know what I mean.