Organ Transplantation - Biotechnology and Your Health: Pharmaceutical Applications - page 124

transplants. Although their long-term use can have serious side
effects, steroids such as prednisone are still widely used. In the
1970s, the introduction of cyclosporine , the product of a soil fungus,
dramatically improved one-year graft and transplant patient
survival. Other widely used chemical immunosuppressive drugs
include tacrolimus, mycophenolate mofetil, and sirolimus. Several
monoclonal antibodies that remove or shut down T lymphocytes
(such as muromonab, daclizumab, and basiliximab) are used to
prevent or treat rejection (Chapter 5). A preparation of animal
antibodies raised against human lymphocytes is still used for the
same purpose. Despite all these tools, slow or chronic rejection of
the organ remains an ongoing problem.
The success of organ transplantation is measured by organ and
patient survival. Over 80% of kidney patients and 65% of their
grafts survive for five years. Patient survival is higher than kidney
graft survival, because kidney graft failure means that patients must
go back onto chronic dialysis and usually back onto the waiting list
for another transplant. Five-year graft and patient survival rates are
lower for other organs. Because there is no counterpart to dialysis
that provides long-term support for those with a failing liver,
lungs, or heart, patients who need these organs often die without a
successful transplant.
TAKING ORGANS FROM OTHER ANIMALS
Because the transplant waiting list continues to grow, scientists
have explored nonhuman animals as a possible source of organs.
Despite the shock and repulsion it sometimes causes, the idea of
xenotransplantation , or transplantation of an organ from one species
to another, deserves some serious consideration.
Organs from Primates
At first, it seemed reasonable to look toward nonhuman primates,
such as chimpanzees and baboons, as organ donors. With experience,