Bone marrow donation is a life-saving medical procedure that provides healthy blood-forming cells to patients with serious diseases. Bone marrow is the spongy tissue found inside certain bones, and its primary function is to produce various types of blood cells, including red blood cells, white blood cells, and platelets. These cells are essential for carrying oxygen, fighting infections, and enabling blood clotting. When a person’s bone marrow is damaged or diseased, a transplant of healthy bone marrow can help restore their body’s ability to produce these crucial cells.
Siblings as Ideal Matches
Full siblings are often considered the best potential donors for bone marrow transplants due to genetic factors. Transplant success largely depends on Human Leukocyte Antigen (HLA) compatibility between donor and recipient. HLAs are proteins on most cells, used by the immune system to distinguish “self” from “non-self.” A close HLA match is necessary to minimize rejection or Graft-versus-Host Disease (GVHD).
Each person inherits half of their HLA markers from each biological parent. This inheritance pattern means full siblings have a 25% chance of a perfect HLA match, sharing all inherited markers. There is also a 50% chance of a half-match and a 25% chance of no match. Identical twins share a nearly identical HLA profile, developing from a single fertilized egg.
Other Family Member Considerations
While full siblings offer the highest probability of a perfect match, other family members can also be potential donors. Parents are always a half-match for their children, inheriting 50% of their HLA markers from each parent. Historically, full matches between parents and children were rare, but advancements in transplant medicine have made half-matched (haploidentical) transplants more feasible.
Children can also be potential donors for their parents, similarly being a half-match. Half-siblings, sharing one biological parent, can be a half-match but not a full HLA match. More distant relatives, like aunts, uncles, or cousins, have a lower chance of being a suitable match as genetic similarity diminishes. These options are still explored, especially when a fully matched sibling is unavailable.
Alternative Donor Options
When a suitable family donor cannot be identified, alternative options are necessary to find a compatible match. National and international registries maintain extensive databases of volunteer unrelated donors. These registries connect patients with life-saving stem cells, encompassing millions of potential donors globally. The search involves comparing the patient’s HLA type against registered donor profiles to find the closest match.
Another alternative source of blood-forming stem cells is umbilical cord blood. Collected from the umbilical cord and placenta after birth, cord blood is rich in stem cells and stored in public cord blood banks. Cord blood transplants may require a less stringent HLA match than adult donor transplants, making them a viable option, especially for patients needing an urgent transplant or those from diverse ethnic backgrounds where finding a perfect adult match is challenging.
Understanding the Donation Process
For suitable family donors, the donation process involves a thorough health evaluation and medical tests to ensure donor safety. There are two primary methods for collecting stem cells: bone marrow harvest and peripheral blood stem cell (PBSC) donation. The choice depends on the patient’s needs and medical considerations.
Bone marrow harvest is a surgical procedure performed under general anesthesia. Liquid bone marrow is collected directly from the donor’s hip bones using specialized needles. This method takes about one to two hours, and donors may experience soreness in the lower back or hips afterwards.
PBSC donation is a non-surgical procedure where the donor receives injections for several days to stimulate stem cell release from the bone marrow into the bloodstream. These cells are collected from the donor’s arm through a process similar to blood or plasma donation, lasting four to eight hours.