The Impact of Cryopreservation on Hematopoietic Stem Cell Engraftment and Post-transplant Outcome During the COVID-19 Pandemic.

BACKGROUND/AIM:The COVID-19 pandemic has had a significant impact on the current management of allotransplanted patients in whom fresh hematopoietic stem cells (HSCs) were replaced by cryopreserved ones. The aim of the study was to determine the efficacy and safety of cryopreserved HSCs when compared with the fresh ones. PATIENTS AND METHODS:A retrospective analysis of 254 allogeneic stem cell transplantations (HSCT) procedures performed between 2020-2021 included the following donors: matched related (MRD; n=68), matched unrelated (MUD; n=148) and haploidentical (HID; n=38). 50% of patients (non-cryo group) received fresh grafts, whereas the remaining patients (cryo group) were transplanted with cryopreserved cells. RESULTS:No differences in terms of median days to neutrophil [MRD/MUD/HID cryo- and non-cryo groups: 17 vs. 16 (p=0.27), 19 vs. 18 (p=0.83), 22 vs. 22 (p=0.83) days, respectively] and platelet [MRD/MUD/HID cryo- and non-cryo groups: 14 vs. 14 (p=0.25), 17 vs. 17 (p=0.33), 21 vs. 19 (p=0.36) days, respectively] engraftments were demonstrated. Among MUD graft recipients, platelet engraftment rates were 81% in the cryo- and 96% in the non-cryo group (p=0.01). OS rates were comparable at 1 year after HSCT between MRD/MUD/HID cryo- and non-cryo groups: 53% vs. 60% (p=0.54), 60% vs. 66% (p=0.5), 50% vs. 41% (p=0.56), respectively. CONCLUSION:During the COVID-19 pandemic, cryopreserved HSCs did not have a negative impact on median engraftment time and OS when compared to fresh HSCs. In the MUD group, platelet engraftment rate was lower in cryopreserved HSC recipients.