Cryopreservation of Unrelated Hematopoietic Stem Cells from a Blood and Marrow Donor Bank During the COVID-19 Pandemic: A Nationwide Survey by the Japan Marrow Donor Program

During the COVID-19 pandemic, donor hematopoietic stem cell grafts are frequently cryopreserved to ensure the availability of graft before starting a conditioning regimen. However, the safety of cryopreservation has been controversial in unrelated hematopoietic stem cell transplantation (HSCT), especially for bone marrow (BM) grafts. In addition, in unrelated HSCT, the effect of the time from harvest to cryopreservation of donor grafts required...