Circulating HSPCs enhance their self-renewal by augmenting the endocytosis and lysosomal acidity via MIF-(CXCR4_CD74)-ATP6V1A axis

Human circulating hematopoietic stem/progenitor cells (cHSPCs) in steady-state blood are a rare, underutilized resource limited by poor ex vivo expansion and unclear regulation. Using an immune-cell screening platform, we found that monocytes most effectively promote cHSPC expansion while preserving long-term hematopoietic reconstitution in serial transplantation. Mechanistically, cHSPCs engage the MIF-(CXCR4_CD74)-ATP6V1A axis to enhance endocytosis and lysosomal acidification, which upregulates CD34 + CXCR4 + cells, reduces ROS, stabilizes HIF-1α, and maintains glycolytic activity and stemness. Monocyte co-culture or pathway agonizts (MIF, EN6) also expanded HSPCs from cord blood, bone marrow, and poor-graft-function patient samples. Thus, cHSPC self-renewal is driven by an MIF-(CXCR4_CD74)-ATP6V1A-dependent mechanism modulating endocytosis, lysosomal function, and metabolism. This offers a universal expansion strategy for diverse clinical sources, including steady-state peripheral blood, cord blood, and functionally compromised hematopoietic cells.