CXCL12/CXCR4 signaling enhances human PSC-derived hematopoietic progenitor function and overcomes early in vivo transplantation failure

Human pluripotent stem cells (hPSC) generate hematopoietic progenitor cells (HPC), but fail to engraft xenograft models, which is a hallmark feature of adult/somatic hematopoietic stem cells (HSC) from human donors. Progress to derive hPSC-derived HSCs has relied on cell autonomous approaches that force expression of transcription factors (TF), however the role of bone marrow (BM) niche remains poorly understood. Here, we quantified a failure of hPSC-HPCs to survive even in the first 24 h upon transplantation into the BM. Across several hPSC-HPC differentiation methodologies, we identified the lack of CXCR4 expression and network function. Ectopic CXCR4 conferred CXCL12-dependent signaling of hPSC-HPCs in biochemical assays and increased migration/chemotaxis and progenitor capacity, as well as survival and proliferation following transplantation in vivo. In addition, hPSC-HPCs forced to express CXCR4 demonstrated a transcriptional shift toward somatic HPCs, but this approach failed to produce long-term HSC engraftment. Our results reveal that independent of differentiation methods, networks involving CXCR4 should be targeted to generate HSCs with in vivo function from hPSCs. Human pluripotent stem cell (hPSC) derived hematopoietic progenitor cells (HPC) were generated using previously described methods; Cytokines & BMP4 (Chadwick et al. Blood 2003) and endothelial-to-hematopoietic transition (EHT) (Lee et al. The Journal of Clinical Investigation 2017). Lentiviral was used to achieve CXCR4+ hPSC-HPCs, differentiated as previously described (Chadwick et al. Blood 2003). Adult/somatic HPCs were isolated from bone marrow, cord blood, and mobilized peripheral blood.