I’d imagine the limiting factor in all of these is still functionality of these organs. We can reorganize them to look somewhat like the actual organ (like in the linked article), but whether or not the organ functions the same is still under much investigation.
Also how do you connect up the nerves? A heart transplant works because the heart is basically self-regulating. But the eye needs thousands of nerves to connect to the brain to be useful.
This is weird because the vagus nerve and breathing rate can both slow/speed up the heart. What about when doing exercise, how is the signal sent to the heart to say speed up?
