Novel SCRG1/BST1 axis regulates self-renewal, migration, and osteogenic differentiation potential in mesenchymal stem cells.

Human mesenchymal stem cells (hMSCs) remodel or regenerate various tissues through several mechanisms. Here, we identified the hMSC-secreted protein SCRG1 and its receptor BST1 as a positive regulator of self-renewal, migration, and osteogenic differentiation. SCRG1 and BST1 gene expression decreased during osteogenic differentiation of hMSCs. Intriguingly, SCRG1 maintained stem cell marker expression (Oct-4 and CD271/LNGFR) and the potentials of self-renewal, migration, and osteogenic differentiation, even at high passage numbers. Thus, the novel SCRG1/BST1 axis determines the fate of hMSCs by regulating their kinetic and differentiation potentials. Our findings provide a new perspective on methods for ex vivo expansion of hMSCs that maintain native stem cell potentials for bone-forming cell therapy.