The Tragedy of Xenotransplantation

The Tragedy of Xenotransplantation

Background and challenges

In 1954, surgeon Joseph Murray started a revolution in the Medical industry by performing the first human organ transplant, a kidney transplant between identical twins(1). Initially, allotransplantation received some hindrance due to the ability of the human immune system to reject any foreign object. With the introduction of cyclosporin, a powerful drug that minimizes the rejection of foreign tissue, allotransplantion possibilities have expanded spectacularly(3). It is no longer necessary to have an exact match of certain blood type markers for a successful human transplant. This means organs from unrelated people can be used. Recipients have a good chance today of living at least five years with an allograft. These days organ transplantation is a norm. Each year about 20,000 Americans receive life saving transplants of heart, kidneys , liver or lungs. Today, allotransplantation faces a significant challenge because the need for this procedure far exceeds the availability of donor organs. Each day, approximately 10 Americans breathe their last breath waiting for organs to become available. To meet this scarcity of human organs, doctors along with pharmaceutical and biotechnology companies are investigating an alternative to allotransplantation, xenotransplantation.

Xenotransplantation, (xeno) is a greek word meaning “stranger”, involves transplanting or grafting of animal organs, tissues, or cells to replace failing organs or to treat disease in humans. These transplanted or grafted organ, tissue, or cell is called a xenotransplant or xenograft. As documented in Table 1, the concept of xenotransplantation dates as back as 1682, but it was not until the 1960's that the technological world stimulated this idea for whole organ transplant. In 1963, Keith Reemtsma transplanted chimpanzee kidneys into thirteen patients. Also, in 1964 Hardy and colleagues from the University of Mississippi used a chimpanzee’s heart as a xenograft. The patients did not survive for long but the transplanted organs showed no sign of rejection. This success inspired more research and development in xenotransplantation, which resulted in the use of this process for therapeutic effects, such as bone marrow transplant in AIDS patients. Although, both whole organ and bone marrow transplants received limited success, the use of pig's heart valves to repair human hearts and porcine pancreatic islet cells to treat diabetes raises the hopes of scientists that someday whole organ xenotransplantation will be possible.