SPP1 and gestational diabetes: However, expression levels of osteoblast-related genes such as osteopontin (OPN), alkaline phosphatase (ALP), osteocalcin (OC), collagen type 1 alpha 1 (Col1α1), and bone sialoprotine (BSP) have been reported to be significantly lower in GDM-MSCs compared to NG-MSCs following osteogenic induction [17,19,21].