Small-Molecule Ice Recrystallization Inhibitors Improvethe Post-Thaw Function of Hematopoietic Stem and Progenitor Cells

摘要

The success of hematopoietic stem cell transplantation depends in part on the number and the quality of cells transplanted. Cryoinjuries during freezing and thawing reduce the ability of hematopoietic stem and progenitor cells (HSPCs) to proliferate and differentiate after thawing. Up to 20% of the patients undergoing umbilical cord blood (UCB) transplant experience delayed or failed engraftment, likely because of the inadequate hematopoietic potency of the unit. Therefore, the optimization of cryopreservation protocols, with an emphasis on the preservation of HSPCs, is an important issue. Current protocols typically utilize a 10% dimethyl sulfoxide cryoprotectant solution. This solution ensures 70–80% post-thaw cell viability by diluting intracellular solutes and maintaining the cell volume during cryopreservation. However, this solution fails to fully protect HSPCs, resulting in the loss of potency. Therefore, a new class of cryoprotectants (N-aryl-d-aldonamides) was designed and assessed for the ability to inhibit ice recrystallization and to protect HSPCs against cryoinjury. Several highly active ice recrystallization inhibitorswere discovered. When used as additives to the conventional cryoprotectantsolution, these nontoxic small molecules improved the preservationof functionally divergent hematopoietic progenitors in the colony-formingunit and long-term culture-initiating cell assays. By contrast, structurallysimilar compounds that did not inhibit ice recrystallization failedto improve the post-thaw recovery of myeloid progenitors. Together,these results demonstrate that the supplementation of cryopreservationsolution with compounds capable of controlling ice recrystallizationincreases the post-thaw function and potency of HSPCs in UCB. Thisincrease may translate into reduced risk of engraftment failure andallow for greater use of cryopreserved cord blood units.