I'm hopeful that someday we'll have a good system for "caging" cells to prevent an immune response (in either direction) while also permitting the visitors to sustain themselves with blood nutrients and regulate hormones or clean waste.
Sort of like the role of the blood-brain barrier, or maybe a placenta.
I am of the glum opinion that the hideously interwoven nature of our immune system is at least partly a security feature rather than an engineering flaw.
That said, we might still learn from the success of its contemporary attackers, who haven't been slacking over the past millions of years either.
Yes! I think there was some work being done with a islet transplant like that. I'm not sure of the details though - it's probably a long way off, if it works.
Sort of like the role of the blood-brain barrier, or maybe a placenta.