Hypoxia regulates Bone Morphogenetic Proteins in rat bone marrow-derived endothelial cells

Bone Morphogenetic Proteins (BMPs) are a family of growth factors known to promote osteogenesis during bone formation. Previously, endothelial cells were reported to secrete BMP2 in response to low oxygen concentration (hypoxia), an environment where bone repair takes place. However, the effect of hypoxia on endothelial cells derived from a bone source as well as the regulation of various BMPs has not been studied. Thus, the aim of this study was to determine the effects of hypoxia on expression of 14 BMPs in rat bone marrow-derived endothelial cells (TRBME2 cells). Quantitative real time polymerase chain reaction (PCR) was performed to determine the mRNA expression of BMPs in the hypoxia treated TRBME2 cells. The results showed various changes in the gene expression profile for the BMPs and subsequent cluster analysis indicated BMPs are co-expressed in five distinct profiles. Moreover, for BMP2, the effect of hypoxia was also noted at the protein level. These results suggest that endothelial cells contribute to bone healing by modulating BMPs under low oxygen concentration. These findings may help to understand the underlying mechanism of BMP treatment in bone repair, and also to identify optimal use of BMPs for improved future clinical applications.