Transplantationens

Transplantation is the process of transferring cells, tissues, or organs from a donor to a recipient to replace damaged or failing biological structures. It encompasses solid organ transplantation, tissue transplantation, and cellular or hematopoietic stem cell transplantation. The goal is to restore function and extend life, often after exhaustion of other therapies.

Solid organ transplantation includes kidneys, liver, heart, lungs, pancreas, and intestine. Tissue transplantation includes cornea, skin, bone, heart valves, and cartilage. Hematopoietic stem cell transplantation replaces bone marrow function and is used for certain cancers and hematologic diseases. In some cases, cells such as islets or islet-like clusters are transplanted to treat diabetes. Xenotransplantation—transfer between species—remains experimental.

Donors may be deceased or living. Living donors provide a kidney or a portion of liver, lung, or pancreas. Organ allocation systems prioritize medical urgency and compatibility, including blood type and HLA compatibility. Matching reduces rejection risk but is not absolute; even well-matched grafts require immunosuppressive therapy.

Rejection is an immune-mediated process. Immunosuppression commonly involves calcineurin inhibitors (e.g., tacrolimus, cyclosporine), antiproliferatives (mycophenolate), and steroids, with newer agents and regimens aiming to reduce toxicity. In transplantation of hematopoietic stem cells, graft-versus-host disease is a key risk.

Outcomes have improved with advances in surgical technique, organ preservation, and immunology, but access, cost, and long-term graft survival remain concerns. Ethical issues include consent, organ trafficking, and equitable distribution. Research into tolerance, regenerative approaches, and bioengineered organs seeks to expand options in the future.