Cell Biochemistry and Biophysics

, Volume 69, Issue 1, pp 141–149 | Cite as

Prolyl Hydroxylase Inhibitors Protect from the Bone Loss in Ovariectomy Rats by Increasing Bone Vascularity

  • Xiaodong Liu
  • Yihui Tu
  • Lianfang Zhang
  • Jin Qi
  • Tong Ma
  • Lianfu Deng
Original Paper


The hypoxia-inducible factor-1α (HIF-1α)/vascular endothelial growth factor (VEGF) pathway is involved in skeletal development, bone repair, and postmenopausal osteoporosis. Inhibitors of prolyl hydroxylases (PHD) enhance vascularity, increase callus formation in a stabilized fracture model, and activate the HIF-1α/VEGF pathway. This study examined the effects of estrogen on the HIF-1α/VEGF pathway in osteoblasts and whether PHD inhibitors can protect from bone loss in postmenopausal osteoporosis. Osteoblasts were treated with estrogen, and expressions of HIF-1α and VEGF were measured at mRNA (qPCR) and protein (Western blot) levels. Further, osteoblasts were treated with inhibitors of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway, and levels of VEGF mRNA and protein expression were detected. In addition, ovariectomized rats were treated with PHD inhibitors, and bone microarchitecture and bone mechanical strength were assessed using micro-CT and biomechanical analyses (lower ultimate stress, modulus, and stiffness). Blood vessel formation was measured with India Ink Perfusion and immunohistochemistry. Estrogen, in a dose- and time-dependent manner, induced VEGF expression at both mRNA and protein levels and enhanced HIF-1α protein stability. Further, the estrogen-induced VEGF expression in osteoblasts involved the PI3K/Akt pathway. PHD inhibitors increased bone mineral density, bone microarchitecture and bone mechanical strength, and promoted blood vessel formation in ovariectomized rats. In conclusion, estrogen and PHD inhibitors activate the HIF-1α/VEGF pathway in osteoblasts. PHD inhibitors can be utilized to protect bone loss in postmenopausal osteoporosis by improving bone vascularity and angiogenesis in bone marrow.


Hypoxia-inducible factor Estrogen Ovariectomy Prolyl hydroxylase inhibitor Osteoblasts 



This work was supported by National Natural Science Foundation of China (NSFC, No.81372015), Shanghai Natural Science Foundation (No. 11ZR1434100) and Shanghai Municipal Health Bureau Project (No. 2013214).

Conflict of interest

The authors have no conflict of interests to declare.


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Copyright information

© Springer Science+Business Media New York 2013

Authors and Affiliations

  • Xiaodong Liu
    • 1
  • Yihui Tu
    • 1
  • Lianfang Zhang
    • 2
  • Jin Qi
    • 2
  • Tong Ma
    • 1
  • Lianfu Deng
    • 2
  1. 1.Department of OrthopedicsThe Central Hospital of YangPu District,YangPu Hospital, TongJi UniversityShanghaiPeople’s Republic of China
  2. 2.Shanghai Key Laboratory for Bone & Joint Disease, Shanghai Institute of Traumatology and Orthopedics, Ruijin HospitalShanghai Jiao Tong University School of MedicineShanghaiPeople’s Republic of China

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