Donor selection for haploidentical hematopoietic cell transplantation- practice guidance

Haploidentical hematopoietic cell transplantation (haplo-HCT) using either T-cell depletion or T-cell repletion (Beijing protocol or post-transplantation cyclophosphamide) has shown great advancements in recent years. Haplo-HCT can achieve comparable outcomes for transplantation from matched sibling donors and unrelated donors and has been used increasingly worldwide. For almost every patient, multiple haploidentical donors are available. Therefore, it is necessary to choose the best donor. However, there is no universal consensus on donor selection. The aim of this review was to discuss the general principles of and controversial factors related to donor selection. Several principles have been widely accepted. For example, human leukocyte antigen disparity is no longer taken into account, donor-specific antibodies should be avoided, and younger donors and ABO matches are preferred. However, factors such as donor gender, family relationship, cytomegalovirus serological status, and natural killer cell alloreactivity are still controversial. Moreover, the factors may depend on the transplantation regimen. Finally, we summarize practical points for donor selection according to different haplo-HCT protocols.