system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is it impossible to transplant a bladder? It seems strange to me that a heart can be transplanted and a bladder can't.
gpt
It's not impossible, it's a weighting of the positives and negatives of a procedure. Transplantation is drastic, dangerous, and life altering. The patient will have to take drugs that suppress their immune system for the rest of their life along with the many side effects that patients will now have to live with. So we generally only do it for stuff that's either not prone to rejection that the patient won't have to spend a lifetime on anti-rejection drugs (i.e. cornea) or for stuff where if the patient doesn't have it they will die.

A heart? You can't live without it. So transplanting easily edges out the risks and possible complications. A bladder? Not so much. Surgeons are good at fashioning bladders from bowel or small intestine, they can create urine accumulation pockets to be drained by cathater, they can route the ureters to a port on the body to be collected by a bag. These are a mere minor inconvenience compared to a lifetime on anti-rejection drugs and a weakened immune system.