What is an allogenic transplant?

An allogenic transplant, also known as an allogeneic stem cell transplant or allogeneic bone marrow transplant, is a medical procedure in which healthy stem cells or bone marrow are taken from a donor and infused into a recipient to replace damaged or diseased bone marrow. Here's an explanation of an allogenic transplant:

1. Donor and Recipient Matching:

- In an allogenic transplant, the stem cells or bone marrow come from a donor who is not genetically identical to the recipient. This means the donor and recipient have different human leukocyte antigens (HLA) markers, which are proteins on the surface of cells that help the immune system distinguish between "self" and "non-self."

2. Donor Selection:

- The donor is typically a sibling or a closely related family member who has similar HLA markers to the recipient. In cases where a suitable related donor is not available, a search may be conducted to find an unrelated donor from a registry of potential donors.

3. Conditioning Regimen:

- Before the transplant, the recipient undergoes a conditioning regimen, which may include chemotherapy, radiation therapy, or both. This regimen helps eliminate any remaining diseased bone marrow and weakens the recipient's immune system to reduce the risk of rejecting the donor cells.

4. Stem Cell/Bone Marrow Collection:

- Stem cells or bone marrow are collected from the donor through a procedure called apheresis or bone marrow harvest. In apheresis, stem cells are collected from the donor's blood, while in a bone marrow harvest, stem cells are extracted from the donor's hip bones.

5. Infusion of Donor Cells:

- The collected stem cells or bone marrow from the donor are then infused into the recipient's bloodstream through an intravenous line. These donor cells travel to the recipient's bone marrow and start producing new healthy blood cells.

6. Engraftment:

- The process of donor cells establishing themselves in the recipient's bone marrow and beginning to produce blood cells is called engraftment. It usually takes several weeks for engraftment to occur.

7. Post-Transplant Care:

- After the transplant, the recipient will receive ongoing medical care and monitoring to manage any complications, prevent infections, and monitor the progress of engraftment. This may involve regular blood tests, medications to manage immune reactions or prevent graft-versus-host disease (GVHD), and supportive care to maintain overall health.

8. Graft-versus-Host Disease (GVHD):

- GVHD is a potential complication of allogenic transplants in which the donor's immune cells recognize the recipient's tissues as foreign and attack them. GVHD can affect various organs and tissues, and its severity can range from mild to life-threatening.

Allogenic transplants are performed to treat various blood-related disorders and conditions, including leukemia, lymphoma, sickle cell disease, aplastic anemia, and immune deficiencies. The success of an allogenic transplant depends on factors such as the compatibility between the donor and recipient, the underlying medical condition, and the recipient's overall health.