These are the responses we received from the offices of the maraje’:
The office of the Grand Ayatullah Khamenei:
If the organs of the donors are used for the cure of other patients, but quicken their death, it is impermissible, other than that, if the surgery is done with the donor’s permission or another ‘muhtaram’ person’s life depends on it, it is permissible.
The office of the Grand Ayatullah Makarem Shirazi:
It is permissible, given that all necessary conditions are met.
The office of the Grand Ayatullah Sistani:
Amputating the organs of a dead Muslim is impermissible and entails diyah, and burying the organ in the case of an organ getting cut off is wajib, unless the life of another Muslim depends on it, which in this case, it will be permissible, but the diyah will still be wajib, unless the donor has willed it himself before his death which will no longer entail the diyah. Nevertheless, if the life of a Muslim doesn’t depend on the organ, and the donor has willed that his organs be donated, acting upon that will be problematic.
The office of the Grand Ayatullah Safi Golpaygani:
In my humble opinion, amputating any organ of a Muslim who hasn’t passed away yet, even if brain death is for sure, it is still impermissible.