Stem Cell Transplant for Sickle Cell Disease
Stem cell transplant is a curative therapeutic option for patients who have failed standard therapy such as hydroxyurea and transfusion. Siblings are the preferred choice of donor in this setting, where graft-versus-host-disease is particularly undesirable. The choice of siblings includes those without sickle cell disease, but also siblings with sickle cell trait. When a sibling trait donor is used in transplantation, the patient with sickle cell disease is converted to sickle cell trait. Sickle trait donors can be safely stimulated with G-CSF and successfully harvested. (Kang, Areman et al. 2002).
In analysis by the National Marrow Donor Program (NMDP) and Center for International Blood and Marrow Research (CIBMTR), 75% of white European patients are likely to find an unrelated fully mached (8 HLA loci out of 8) donor. Unfortunately, the match rate for other ethnic groups is much lower. Approximately 14% of sickle cell patients have a fully matched (8/8 HLA loci) unaffected sibling, and only 19% have a matched unrelated donor in the National Marrow Donor Program registry. Even if a matched donor is located, they may not be truly available, committed or medically fit to donate. The overall donor availability rate is only 23% of fully matched registrants.
Reference:
Kang, E. M., E. M. Areman, V. David-Ocampo, C. Fitzhugh, M. E. Link, E. J. Read, S. F. Leitman, G. P. Rodgers and J. F. Tisdale (2002). "Mobilization, collection, and processing of peripheral blood stem cells in individuals with sickle cell trait." Blood 99(3): 850-855.
Gragert, L., M. Eapen, E. Williams, J. Freeman, S. Spellman, R. Baitty, R. Hartzman, J. D. Rizzo, M. Horowitz, D. Confer and M. Maiers (2014). "HLA Match Likelihoods for Hematopoietic Stem-Cell Grafts in the U.S. Registry." New England Journal of Medicine 371(4): 339-348.
