Allogeneic hematopoietic stem cell transplantation (allo-HSCT) typically utilizes fresh donor bone marrow (BM) or peripheral blood stem cells (PBSCs) because of concerns that cryopreservation may negatively impact patient outcomes. 1 The COVID-19 pandemic spurred renewed interest in the impact of cryopreservation after the National Marrow Donor Program (NMDP) mandated cryopreservation of unrelated donor (URD) PBSCs between March and August 2020. 2

Although the cryopreservation mandate was lifted after August 2020, heterogeneity in cryopreservation practices among transplant centers remains. Moreover, data on long-term outcomes of using such products are scarce. We previously reported lack of difference in 6-month overall survival (OS), progression free survival (PFS), relapse, and nonrelapse mortality (NRM) for adult recipients of cryopreserved PBSCs compared with those of fresh URD PBSCs, noting lower T-cell chimerism at days 30 and 100. 3, 4 We and others reported delayed neutrophil and platelet reconstitution with cryopreservation, 3, 5 whereas other investigators found no difference. 6, 7 Although some studies have reported increased moderate/severe chronic graft versus host disease (cGVHD) after allo-HSCT with cryopreserved PBSCs, 5, 6 others have described equivalent or slightly reduced cGVHD incidence, 7, 8 although differences in GVHD prophylaxis regimens and small sample sizes may account for this variability.