One doctor hopes to get that list down to zero.
Stored inside a lab at the Children's Hospital in Los Angeles, doctor Roger De Filippo, is using stem cells taken from amniotic fluid, which surrounds fetuses in the womb, to heal damaged kidneys.
The stem cells can actually help a dying kidney fix itself.
The doctor believes the same stem cells could be injected directly into a patient's diseased organ.
It could change the future for people suffering from acute kidney disease, diabetes and genetic disorders.
The stem cells said to regenerate kidneys are from fluids collected after childbirth.
There is an endless supply of them.
This type of cell can not only be used for kidneys, but they can adapt to any other type of organ as well.