What Types of Stem Cell Donors Are Available? How Do Related and Unrelated Donors Differ?
Overview: Allogeneic hematopoietic stem cell transplantation (allo-HSCT) uses healthy blood-forming stem cells from another person. Finding an appropriate donor is therefore a key part of transplant planning. Donors may be related or unrelated, and they may also be described according to the degree of human leukocyte antigen (HLA) matching. With advances in transplant techniques, a fully matched donor is no longer the only possible option for some patients.
Why is a donor needed?
Autologous transplantation uses the patient's own previously collected stem cells, while allogeneic transplantation uses stem cells from a healthy donor. After the patient receives conditioning treatment, donor cells are infused to help rebuild the blood-forming and immune systems.
What types of donors are available?
Related donors include siblings, parents, children and, in some situations, other relatives. Full siblings may have a higher chance of being closely HLA-matched, but testing is still required. Parents and children are commonly haploidentical, or half-matched, donors. Unrelated donors have no blood relationship with the patient but may have a suitable HLA match; they are usually identified through donor registries in China or internationally.
By HLA match, donors may be fully matched or haploidentical. HLA helps the immune system distinguish self from non-self, and closer matching generally reduces immune-related transplant risks. Haploidentical transplantation has become an important option as transplant methods have improved.
What if there is no fully matched donor?
Not having a fully matched donor does not automatically rule out transplantation. The transplant team considers the patient's disease, disease risk and timing of transplant together with the donor's HLA profile and health. A haploidentical related donor or an unrelated donor may still be appropriate for some patients.
Is a young male always the best donor?
No. Age and sex are only part of the assessment. HLA matching, overall health, infection risk, medical history and possible inherited risks also matter. Donor selection should be made by the transplant team based on the full clinical picture.