Haploidentical or half-matched donor bone marrow transplantation (BMT) is the sole available treatment option for individuals with blood disorders who have been recommended for BMT but lack a fully HLA-matched family donor or a matched unrelated donor. A Haploidentical Transplant is a form of Allogeneic Transplant that utilizes healthy blood-forming cells from a half-matched donor to replace the unhealthy ones. Typically, the donor is a family member. The patient’s blood is tested by the doctor to determine their Human Leukocyte Antigen (HLA) type. Doctors search for a donor or umbilical cord blood that closely matches the patient’s HLA. However, in cases where a close HLA match cannot be found, a haploidentical transplant may be considered. This type of allogeneic transplant involves a donor who is an exact half-match for the patient’s HLA. Usually, the haploidentical or half-matched donor is the patient’s mother, father, or child, as parents are always a half-match for their children. For some individuals, a transplant from a half-matched donor or a haploidentical transplant is a viable treatment option. Siblings have a 50% chance of being a half-match for each other, while other family members such as cousins, aunts, or uncles are unlikely to be a half-match. Therefore, these readily available donors are suitable for most patients.

The transplants previously had a high rejection rate, slow immune system recovery, and a significant risk of treatment-related mortality. However, advancements in transplant immunology and T cell depletion techniques have drastically improved the success of Haploidentical Bone Marrow Transplants. T cell depletion is crucial for success in Haploidentical HSCT.