SOLID ORGAN TRANSPLANTATION OUTCOMES
The kidney was the first successfully transplanted
human organ. Even when the donor is not an identical twin, patients can do well
for some time with grafts from live donors and from unrelated and often totally
unmatched cadaveric donors. The half-life of kidney transplants has been
increasing and is currently more than ten years. Failures are mainly due to
chronic rejection, nephrotoxicity of the calcineu-rin inhibitor agents, and
recurrent disease. Liver and heart transplantation have also provided excellent
treatment for many patients. The empiric clinical observation is that livers
are more tolerogenic than other solid organ allografts, but the basis for this
has not been clearly established. The most common indication for liver
transplan-tation is now hepatitis C, but this almost invariably recurs in the
graft and can lead to liver failure irrespective of rejection and other causes
of graft loss. The chief complication of heart allografts is chronic rejection,
which involves the coronary arteries with accelerated atherosclerosis. There
have now been many cases of bilat-eral lung transplantation with or without the
heart; however, the main problem is that the alveoli are particularly
susceptible to rejection.
A major conceptual advance in the treatment of
diabetes was the successful trans-plantation of islets of Langerhans by a group
in Edmonton led by James Shapiro. The early results were excellent using an
immu-nosuppressive protocol with no steroids and treating patients suffering
from hypo-glycemia. Most patients required two islet cell donors to reach a
euglycemic state. At one year, 80 percent of patients no longer required
insulin support. This fell to about 75 percent at two years but deteriorated
more quickly thereafter. This study was an important proof of principle that
islet cell transplantation could achieve good results. Significant obstacles
still remain, however, including the exhaustion of transplanted islet cells,
control of chronic rejection, balancing the toxicities of immunosup-pressive
drugs, and preventing recurrent autoimmune destruction in type I diabetes.
There is continued enthusiasm for the prospect of
xenogeneic transplantation of organs and tissues from animals to man, but to
date there have been no long-term successes. The best result occurred in the
1960s, when Reemtsma transplanted a kidney from a chimpanzee to a patient who
achieved adequate graft function for nearly ten months. There are many
difficulties, however, with xenografting. In addition to hyperacute rejection,
accel-erated rejection, and other immunological factors, there are
physiological consider-ations regarding organ size disparities and whether
xenogeneic proteins will function satisfactorily in man.
Related Topics
Privacy Policy, Terms and Conditions, DMCA Policy and Compliant
Copyright © 2018-2024 BrainKart.com; All Rights Reserved. Developed by Therithal info, Chennai.