Molecular mechanisms of endothelial osteoinductive/osteosupressive properties

In vivo, osteogenesis is tightly connected with capillaries and endothelium assumed to be one of the main regulators of osteogenic differentiation of underlying mesenchymal cells. In our experiments in vitro, we cultured human osteoblasts and human umbilical vein cord endothelial cells (HUVEC) in osteogenic conditions in direct joint culture and in a separated joint culture where cells were separated with membrane permeable for proteins, but not for the cells. We revealed that in direct co-cultivation endothelial cells enhance osteoblast differentiation, but in separated co-cultures endothelium completely inhibits osteogenic differentiation. To understand the molecular mechanisms of these osteoinductive/osteosupressive properties we performed RNA-seq analysis of control cultures and cells from joint cultures. To separate cells from direct co-culture, we used magnetic sorting.