DNA & Transplants

[ScaryMonster]

There is a hypothetical scenario: a man without a hand has a hand transplanted onto the stump of his arm, the man is treated with the necessary drugs to avoid tissue rejection and the transplant is successful. So if you were to take DNA from above the join on the stump the DNA would belong to the transplant patient and the DNA from the hand would be that of the transplant donor.

Now my question is if over a period of time all the cells in the arm replace themselves, would not the cells in the hand be replaced by cells with DNA makers the transplant recipient?

 

[Hercules Rockefeller]

.....would not the cells in the hand be replaced by cells with DNA makers the transplant recipient?

No, I don’t think so.

Skin, skeletal muscle and bone regeneration from stem cells is localised. Stem cells that regenerate these tissues in the donor hand will have come with the hand from the donor. I’m not aware of any major migration of these cell types. But there would likely by some small overlap of donor/recipient DNA in the muscle/bone/nerve tissue at the joining point.

Blood, of course, is another matter. Recipient DNA from blood cells will be found in the donor hand.

 

[ScaryMonster]

So basically the transplant recipient will have to take the anti rejection drugs for the rest of their lives! You said that there probably is a small migration of cell types.
Might it be possible to artificially induce this sort of migration on a lager scale, so that it could encompass the entire limb or organ?

 

[Hercules Rockefeller]

So basically the transplant recipient will have to take the anti rejection drugs for the rest of their lives!

Yes (unfortunately).

Might it be possible to artificially induce this sort of migration on a lager scale, so that it could encompass the entire limb or organ?

Hmmmm, not really. We could envisage some sort of science fiction scenario, but that's all it would be. I can see no such technique being developed any time soon with any existing technology.

 

[nucleotideboy]

Might it be possible to artificially induce this sort of migration on a lager scale, so that it could encompass the entire limb or organ?

Possibly but it would probably be massively undesirable. Cell migration into different areas of the body is quite rare and in fact the control mechanism for this is not really well understood at the moment.

The reason I say undesirable is that actually the ability for cells to migrate around the body is one of the little tricks common to cancer, which is essentially how metastases occur. Cancer cells somehow overcome the body's strictly regulated (but currently mysterious) mechanisms for staying put.

I suspect deliberately overcoming this mechanism would not be a great plan. But I acknowledge that I speak from the unscientific position of a gut feeling!

 

[ScaryMonster]

With a transplant how they get the tissue to heal together? I imagine its one of the effects of the anti rejection drugs. But how does it work?
Is the scar tissue some kind of genetic composite of the donor and recipient? And hypothetically if you were to grow a clone from this tissue who genetically who would you get?