It is characterized by fibrosis, which is the thickening and scarring of connective tissue, in the transplanted organ. This scarring can lead to a variety of disorders depending on the type of transplant that occurred. There are quite a few factors that increase the risk of chronic rejection, including a previous episode of acute rejection, posttransplant infection, and inadequate immunosuppression. Another type of rejection associated with stem cell transplants is called graft versus host disease (GVHD). It develops when the donor’s immune cells attack the patient’s normal cells. GVHD can occur very soon after transplantation or many weeks after and, depending on its severity, can lead to a range of syndromes including dermatitis, hepatitis, and enteritis. All of these types of rejection can be treated using immunosuppression …show more content…
Pigs and primates are currently being considered as a source of organs for xenotransplantation. The pig is a model organism for this type of transplant because it has decreased time needed to reproduce and mature, and has organs very similar in size to humans. There are multiple barriers, however, that xenotransplantation must overcome in order to be successful. The most obvious problem arises because host and donor are different species, and therefore contain very different antigens in their bodies. This means that there is simply more for the immune system to identify as foreign and destroy, increasing the risk of organ transplant rejection. Another barrier to xenotransplantation includes the possibility of diseases bypassing the species barrier and infecting humans. All in all, xenotransplantation has been seen as a possible effective tool for increased acceptance of organ transplants. In general, organ transplant is made the most successful when it is accompanied with immunosuppression drugs that prevent the host immune system from attacking the foreign transplant organ. When not controlled, this attacking can result in any three stages of rejection, along with graft versus host disease