Hematopoietic cells emerging from hemogenic endothelium exhibit lineage-specific oxidative stress responses

During human embryogenesis, distinct waves of hematopoiesis give rise to various blood cell types, originating from hemogenic endothelial (HE) cells. As HE cells reside in hypoxic conditions in the embryo, we investigated the role of hypoxia in human endothelial to hematopoietic transition and subsequent hematopoiesis. Using single-cell RNA sequencing, we describe hypoxia-related transcriptional changes in different HEderived blood lineages, which reveal that erythroid cells are particularly susceptible to oxidative stress, due to decreased NRF2 activity in hypoxia. In contrast, nonerythroid CD45+ cells exhibit increased proliferative rates in hypoxic conditions and enhanced resilience to oxidative stress. We find that even in normoxia, erythroid cells present a clear predisposition to oxidative stress, with low glutathione levels and high lipid peroxidation, in contrast to CD45+ cells. Intriguingly, reactive oxygen species are produced at different sites in GPA+ and CD45+ cells, revealing differences in oxidative phosphorylation and the use of canonical versus noncanonical tricarboxylic acid cycle in these lineages. Our findings elucidate how hypoxia and lineages, uncovering critical transcriptional and metabolic pathways that influence blood cell development.