The primary goal of this pilot study is to determine the safety and feasibility of the preparative regimen for HSCT using a novel reduced toxicity regimen for stem cell transplant with unrelated donors. Analysis will be geared to confirm if the study regimen, followed by an appropriately HLA-matched unrelated donor (MUD)or unrelated cord blood HSCT, can lead to durable donor engraftment with reasonable toxicity, inhibiting sickle erythropoiesis and limiting disease related organ toxicity in patients who are at high risk for morbidity and mortality associated with sickle cell disease (SCD).
