I dont know, i am sure that its being done right now.. and it has allready taken place.... so yeah...
one day you'll have extra parts of your bodies, waiting there untill u have a hartattack.. and then u just say. i want my hart.. or a new kidney.. or a new new leg.. or a new ear.. or a new nose.. or a new eye.. or a new penis
haha
or some new titties... all is possible...