What are stem-cell donor registries and how do they work?

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A bone marrow registry allows eligible people to register as potential donors. Registration usually involves providing a cheek or buccal swab for HLA typing. File photograph

Last month, Tamil Nadu Health Minister K.G. Arunraj said Tamil Nadu would soon create a stem cell/bone marrow registry to facilitate bone marrow transplantation. At present, 50 patients are on the waitlist for bone marrow transplantation in T.N., he said.

A stem-cell donor registry is a database of people who have voluntarily agreed to potentially donate their blood-forming stem cells to a patient in need. Their human leukocyte antigen (HLA) profile is recorded for comparison with patients looking for a suitable donor.

For people living with blood cancers such as leukaemia and lymphoma, and disorders such as thalassaemia and aplastic anaemia, a stem-cell transplant can be a potentially curative treatment. But finding a suitable donor can be the first challenge. Only about 25% to 30% of patients have a fully HLA-matched sibling donor. For those without a suitable family donor, an unrelated donor registry can provide another route to finding a match.

A bone marrow registry allows eligible people to register as potential donors. Registration usually involves providing a cheek or buccal swab for HLA typing.

Although these are commonly called bone marrow registries, they are essentially stem-cell donor registries, says Jeyasankar S., consultant, medical oncology, haematology, haemato-oncology and bone marrow transplant, Apollo Speciality Hospitals, Vanagaram, Chennai.

If a patient does not have a suitable family donor, the transplant team can search the registry for an unrelated donor. The search can also extend to international donor networks.

The key factor in matching is HLA, rather than the blood group. HLA markers are proteins that help the immune system distinguish the body’s own cells from foreign cells. They are inherited, and a closer HLA match can improve the chances of a successful transplant and reduce complications such as graft-versus-host disease.

The patient’s HLA profile is compared with those of registered donors. If a potential match is identified, the donor is contacted and further testing is done before donation.

A.R. Jaswanthini, haematologist, haemato-oncologist and bone marrow transplant physician, VS Hospitals, Chennai, says a patient without a matched family donor can be searched against potentially large numbers of registered donors. A donor in one part of India, or another country, may eventually be found to be a suitable match for a patient they have never met.

India does not have a single national stem-cell donor registry. The World Marrow Donor Association currently lists five donor registries in the country, DATRI Blood Stem Cell Donors Registry, DKMS Foundation India, Marrow Donor Registry India (MDRI), GeneBandhu and The Arjan Vir Foundation.