In mixed hematopoietic chimerism, the donor red cells win.

摘要

Allogeneic hematopoietic stem cell transplantation (HSCT) was first observed to correct the tha-lassemias and hemoglobinopathies over three decades ago.1'2 Since then, over 3000 transplants for these disorders have been performed worldwide, and allogeneic HSCT currently remains the only proven curative therapy for these highly morbid and life-limiting diseases. In these settings, engraftment of donor-derived cells following HSCT serves to replace dysfunctional cells of the red cell lineage. For over a decade, it has been recognized that a subset of patients transplanted for these disorders intriguingly demonstrate stable and durable co-existence of nucleated donor cells with host cells and that this chimeric state is associated with transfusion-independence and the lack of continued clinical manifestations of their disease.3'4 Now, in a study presented in this issue of the journal, Andreani et al.5 definitively demonstrate that patients with long-lasting stable mixed hematopoietic chimerism (3 with thalassemia and 1 with sickle cell disease), including mixed chimerism of marrow erythroid progenitors, expressed a 2- to 5-fold enrichment of donor-derived mature erythrocytes in the peripheral blood.