RecruitingEarly Phase 1Drug trialStudy of Nicotinamide Riboside Supplementation in Allogeneic Hematopoietic Cell TransplantationThe purpose of this study is to find a safe and tolerable way to improve engraftment after transplant. Research studies have shown that adding nicotinamide riboside to donor cells has the potential to increase blood stem cell numbers and potentially decrease the time to engraftment. Also, nicotinamide riboside, TRU NIAGEN (the study drug) is a type of vitamin B supplement that the general public can get without a prescription and is well tolerated.