Osteogenesis during bone modeling and remodeling is coupled with angiogenesis . A recent study showed that a specific vessel subtype, strongly positive for CD31 and endomucin (CD31hiEmcnhi) , couples angiogenesis and osteogenesis .
Here , we found that platelet-derived growth factor-BB (PDGF-BB) secreted by preosteoclasts induces CD31hiEmcnhi vessel formation during bone modeling and remodeling . Mice with depletion of PDGF-BB in the tartrate-resistant acid phosphatase–positive cell lineage show significantly lower trabecular and cortical bone mass , serum and bone marrow PDGF-BB concentrations , and fewer CD31hiEmcnhi vessels compared to wild-type mice.
In the ovariectomy (OVX)-induced osteoporotic mouse model , serum and bone marrow levels of PDGF-BB and numbers of CD31hiEmcnhi vessels are significantly lower compared to sham-operated controls .
Treatment with exogenous PDGF-BB or inhibition of cathepsin K to increase the number of preosteoclasts, and thus the endogenous levels of PDGF-BB, increases CD31hiEmcnhi vessel number and stimulates bone formation in OVX mice .
Thus , pharmacotherapies that increase PDGF-BB secretion from preosteoclasts offer a new therapeutic target for treating osteoporosis by promoting angiogenesis and thus bone formation .