I'm not sure if this is the correct place for this question - if not, happy for the mods to move it where they think best.

In the story I'm currently writing, one of the protagonists takes part in an experimental medical trial. The researchers are trying to grow a new, specialised organ within adult bodies, and I'm looking for pointers on how this might be achieved. While the procedure is fantastical, I would like to avoid falling into too many of the usual "magical genetic engineering" holes.

My immediate thought is that this is like the intentional creation of a tumour - and indeed, it's useful for the story if there's a risk of creating a damaging, cancerous growth - but I am open to other possibilities. Another avenue that has occurred to me is some kind of gene therapy. It's important for the story that the procedure is carried out on adults rather than embryos - I don't know if that makes a difference.

I am very happy to do further research on this, but I am not a biologist and have only a superficial understanding of medicine, so I need guidance on which topics I should investigate.

I am interested in:
- how the researchers might create a growth of tissue within the body
- how they might trigger that change in an adult individual (delivery mechanism)
- how they might control the form of tissue growth (i.e. to grow this new organ rather than replicating existing tissue)
- how they might prevent the organ being passed hereditarily to offspring (the organ design is their intellectual property and they want to sell the procedure to new generations, rather than having it passed on)

Any pointers or suggestions are welcome. Rep points and good vibes for all responses!