Is it immoral to preserve human parts from a dead person?

People suffer from eye blindness, kidney, lungs, etc. Would it be immoral to preserve human spare parts from a dead person to help people living but suffering from defective organs? Do modern legal systems forbid this? How about religions? I do not know about what is provided in modern legal systems national or international. As far as religion is concerned, one can argue in favour of preserving human spare parts from a dead person based on reasons. The key mission of any religion is good deed. One of the good deeds is, thus, helping people to live without suffer. Thus, preserving human parts from a dead person in order to replace the damaged organ of a living person is more than good. It is understood that individuals donate one of their kidney and other parts to their relatives or anyone whom they love or like to help at their will and there is no legal as well as religious restriction or condemnation in this regard. But can it be immoral to legalize it by international laws or conventions to help people living but suffering from damaged organs?