Cornell scientists use 3-D printer, living-cell injections to create new ears

[Posteritatis]

3. I'm utterly certain people are thinking of it, since it's definitely a known problem

Prosthetics - or, in this case, newly grown replacement parts - are (relatively) easy on their own, but handling sensation properly is right on the edges of medical science these days, especially with body parts as, ah, specialized as those affected by reassignment surgery.

It's the same reason we've had artificial hearts for awhile but don't have artificial lungs and are really struggling with artificial kidneys - the more complex a part, the more stuff it has to do, the more types of wiring running through it, the harder it is to reproduce.

Stuff like this, or the wholly prosthetic arm being tested later this year that can carry sensation, are definitely steps along the way though. Getting everything to behave properly is a huge, huge, huge challenge, though; if someone made the breakthroughs necessary to allow completely functional reassignment surgeries to become commonplace, they'd be a shoe-in for a Nobel for that alone, never mind the zillions of spinoffs something like that would allow.