An effective treatment option for several blood cancers, and one which often results in a cure, is hematopoietic stem cell transplantation (HSCT). In addition to blood cancers, this procedure is invoked in the treatment of other serious illnesses including lymphomas, immune-deficiencies, and anemias. In all these instances an allogeneic HSCT is required, in which a matched donor is the source of healthy HSCs.
‘Matching’ involves the identification of human leukocyte antigens (also called HLA), which are proteins present on the surface of the transplanted cells, and ensuring that those present on the donor cells are compatible with the patient receiving these cells. This is dependent on genetics, and it thus follows that a match will be procured from a donor of the same ethnic background. Unfortunately, at the present time the probability of an Indian finding a matched donor in an international registry is approximately 10% (compared with the 80% probability of a Caucasian finding a match). Thus, there is an urgent need for increased representation of donors of Indian and south-east Asian descent in international donor banks, including those right here in America.
The quest for a suitable donor usually begins with finding a match with a sibling or a relative, but only an estimated 30% of matches are found from within relatives. More often than not an unrelated donor is sought and a wider net is cast that spreads over three source tissues, and the repositories which house them. Three sources of tissues may be used as starting material for a HSCT: (1) bone marrow harvested from the pelvic bone, (2) peripheral blood stem cells (PBSC) isolated from blood after being mobilized from marrow, and lastly (3) cord blood (CB) stem cells. The first two are harvested from adult donors (optimally 18-45 years of age), while the third one is harvested from the umbilical cord after childbirth. Of these, the bone marrow and peripheral blood derived stem cells are preferred as they pack a concentrated bolus of stem cells. Cord blood has advantages in that the requirements for a match is less stringent, but the number of stem cells per sample is limited and the time taken for engraftment is longer. Another significant difference lies in logistics and infrastructure. Registries exist for the adult-derived stem cells where a database is created to record HLA characteristics of registered samples. Once a match is identified the donor is contacted and tissue harvested, processed, and shipped to the recipient’s hospital. In contrast, physical samples of cord blood harvested at the time of childbirth are stored in tissue banks awaiting a request once a match is identified.
Prominent international stem cell banks and registries include the World Marrow Donor Association (WMDA) which is headquartered in the Netherlands, and the Anthony Nolan Trust based in the UK. The Be The Match registry (also the National Marrow Donor Program (NMDP)) is maintained by the Health Resources and Services Administration (HRSA) of the US Department of Health and Human Services (https://bloodcell.transplant.hrsa.gov/index.html), and in addition to the registry provides a trove of information about current research and options available to patients. As there is a widely acknowledged need for donors of non-Caucasian ethnicities in these international banks, the HRSA also provides information related to initiatives and funding for establishing registries focused on these populations. One such initiative is a California-based non-profit Mixed Marrow that is focused on finding bone marrow and blood cell donors of multi-ethnic descent. South Asian Marrow Association of Recruiters (SAMAR) is a community-based network partner and official recruitment center of the Be The Match Registry. Although they were initially focused on recruitment of the South Asian ethnic group, they now serve diverse racial groups. Information may be obtained for other registries including DKMS and Gift of Life.
Of specific interest to patients of Indian and South-east Asian ethnicities are stem cell registry and banking initiatives in India. Currently five registries exist, namely, Marrow Donor Registry India (Mumbai), Genebandhu (Delhi), Bangalore Medical Services Trust (Bangalore), Datri (Chennai), and Jeevan Stem Cell Foundation (Chennai). Jeevan also houses a cord-blood bank. In addition, there is an ongoing initiative of the Government of India to create a national registry. Dr. Srinivasan Periathiruvadi, Chairman of Jeevan, estimates that when the registry touches the million mark approximately 60% of patients of Indian origin will find a matching donor. Since 45% of the Indian population is between the ages of 18-45 which is optimal for a donor, he opines that reaching this goal should be possible in a year or two. HLA typing is performed on registered donors, and once matched, the requisite tissue sample may be shipped to national and international transplantation sites.
India Currents editor Nirupama Vaidhyanathan remembered a high-profile campaign in the South Asian community about 10 years ago in the Bay area, when there was a big push to include participation among Indian-Americans in bone marrow registries. “The registration process was very simple,” she said, “I went to the Hindu temple in Fremont – volunteers swabbed inside my mouth for a sample and then sent the details to the registry. I was contacted about five years later saying that there was a possible match with a patient. Then, they contacted me again saying that they had found a match that was even closer to the patient’s tissue structure. I am still registered and I encourage all to do so. I can only imagine the pain that family members go through when they try to hunt for a possible donor.”
Registering in a database is not difficult, and instructions for sample submission, along with the relevant form, is available on the respective websites. Data obtained from the HLA typing is stored in the database, and the donor will be contacted only when there is a potential match. Donations are usually performed by isolation of PBSCs, which is likened to a prolonged session of blood donation and is appreciably less intrusive than marrow extraction from the pelvic bone. Cord blood is collected from the umbilical cord which is usually discarded, and may be donated with little effort. Both these actions can save lives.
As a community we could contribute to the health of our generation and the next by creating robust registries and cord blood banks. Having this option to fall back upon in the face of a dreadful illness could indeed be a blessing for the international community of South Asian descent.
L Iyengar has a Ph.D., and has been involved in researching the biology of stem cells for about two decades. She has been involved in research programs both in the USA and India.