Repair of Critical-Sized Rat Calvarial Defects Using Genetically Engineered Bone Marrow-Derived Mesenchymal Stem Cells Overexpressing Hypoxia-Inducible Factor-la

摘要

The processes of angiogenesis and bone formation are coupled both temporally and spatially during bone repair. Bone marrow-derived mesenchymal stem cells (BMSCs) have been effectively used to heal criticalsize bone defects. Enhancing their ability to undergo angiogenic and osteo-genic differentiation will enhance their potential use in bone regeneration. Hypoxia-inducible factor-la (HIF-la) has recently been identified as a major regulator of angiogenicosteogenic coupling. In this study, we tested the hypothesis that HIF-la gene therapy could be used to promote the repair of critical-sized bone defects. Using lentivirusmediated delivery of wild-type (HIF) or constitutively active HIF-la (cHIF), we found that in cultured BMSCs in vitro, HIF and cHIF significantly enhanced osteogenic and angiogenic mRNA and protein expression when compared with the LacZ group. We found that HIF-la-overexpressing BMSCs dramatically improved the repair of critical-sized calvarial defects, including increased bone volume, bone mineral density, blood vessel number, and blood vessel area in vivo. These data confirm the essential role of HIF-la modified BMSCs in angiogenesis and osteogenesis in vitro and in vivo.