In a message dated 9/9/99 9:59:56 PM Pacific Daylight Time, firstname.lastname@example.org writes:
> I would comment, that our engineering is getting pretty specific, e.g.
> "Mice lacking all conventional MHC class II genes", PNAS 96:10338-10343.
> The next step in this process is - "enginerring humanized mouse models
> of human MHC-II-associated autoimmune disorders" (perhaps including
> diabetes, rhumatoid arthritis, etc.).
Yes, our engineering is getting specific and we already do things like extralarge mice routinely.
> > > If it looks like something you already grow, you could probably
> > > them in a fairly ad hoc fasion.
> > Yes, but it gets harder away from pet organisms. Details matter; a lot
> > these things are concentration-dependent and you have to get the
> > concentrations right. It's a real problem for "engineering" people -
> > in addition to ethical issues about lack of choice there's a very high
> > chance that you'd make a few goofs fine-tuning the process and that's
> > *really* unacceptable.
> Why? If we can do it on adults with informed consent, I can open
> "Robert's Spare Body Parts For U" and the spares can go up for grabs
> on eBay! You get your 5-fingered hands, your 4-fingered hands, your
> 2-thumbed hands, the possibilities are simply endless.
Well, yes, but developmental genes are off in adults. The developmental tweaks we're getting good at are ineffective in adults and unsafe for children.
For spare parts we need
in vitro organs plus reactivation of neural development. We still can't do that in any system, never mind routinely. We can grow things like ears but a hand is well over a decade off.