UCLA

Unlimited self renewal capacity and differentiation potential make human pluripotent stem cells (PSC) a promising source for the ex vivo manufacture of red blood cells (RBC) for safe transfusion. Current methods of erythropoiesis from PSC suffer from low yields of RBCs, most of which contain embryonic and fetal rather than adult hemoglobin. We have previously shown that homo-dimerization of the intracellular component of MPL (ic-MPL) induces erythropoiesis from human cord blood progenitors through unique, EPO-independent mechanisms. The goal of the present study was to investigate the potential of ic-MPL dimerization to induce erythropoiesis from human embryonic stem cells (hESC) and to identify the signaling pathways activated by this strategy. I present here evidence that ic-MPL dimerization induces EPO-independent erythroid differentiation from hESC through AKT signaling, by generating erythroid progenitors and promoting definitive erythropoiesis with increased RBC enucleation as well as increased gamma:epsilon globin ratio and production of beta-globin protein. ic-MPL dimerization is significantly more potent than EPO in inducing erythropoiesis from hESC and activates a network of key erythroid factors involved in apoptosis, cell cycle, and differentiation. These findings open up potentially new approaches toward the generation of therapeutically relevant RBCs for transfusion.