Transient regulation of RNA methylation in human hematopoietic stem cells promotes their homing and engraftment.

Enhancing the efficiency of hematopoietic stem cell (HSC) homing and engraftment is critical for cord blood (CB) hematopoietic cell transplantation (HCT). Recent studies indicate that N 6 -methyladenosine (m 6 A) modulates the expression of mRNAs that are critical for stem cell function by influencing their stability. Here, we demonstrate that inhibition of RNA decay by regulation of RNA methylation, enhances the expression of the homing receptor chemokine C-X-C receptor-4 (CXCR4) in HSCs. We show that YTH N6-methyladenosine RNA binding protein 2 (YTHDF2), a m 6 A reader and FTO α-ketoglutarate dependent dioxygenase (FTO), a m 6 A eraser play an opposite role in this process. Through screening, we identified several FDA-approved compounds that regulate the expression of YTHDF2 and FTO in CB CD34 + cells. We show that transient downregulation of YTHDF2 or activation of FTO by using these compounds inhibits CXCR4 decay in CB HSCs and promotes their homing and engraftment. Our results demonstrate a novel regulation strategy to enhance the function of CB HSCs and provide a translational approach to enhance the clinical efficacy of HCT.