Metformin coordinates osteoblast/osteoclast differentiation associated with ischemic osteonecrosis.

See-Hyoung Park,Young Jae Moon,Kyu Yun Jang,Mi-Ae Kang,Jung Ryul Kim

doi:10.18632/aging.102796

See-Hyoung Park, Young Jae Moon + Show 3 more

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https://doi.org/10.18632/aging.102796

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Abstract

In this study, we aimed to identify a candidate drug that can activate endogenous Angiopoietin 1 (Ang1) expression via drug repositioning as a pharmacological treatment for avascular osteonecrosis. After incubation with 821 drugs from the Food and Drug Administration (FDA)-approved drug library, Ang1 expression in U2OS cell culture media was examined by ELISA. Metformin, the first-line medication for treatment of type 2 diabetes, was selected as a candidate for in vitro and in vivo experimental evaluation. Ang1 was induced, and alkaline phosphatase activity was increased by metformin treatment in U2OS and MG63 cells. Wound healing and migration assay showed increased osteoblastic cell mobility by metformin treatment in U2OS and MG63 cells. Metformin upregulated expression of protein markers for osteoblastic differentiation in U2OS and MG63 cells but inhibited osteoclastic differentiation in Raw264.7 cells. Metformin (25 mg/kg) protected against ischemic necrosis in the epiphysis of the rat femoral head by maintaining osteoblast/osteocyte function and vascular density but inhibiting osteoclast activity in the necrotic femoral head. These findings provide novel insight into the specific biomarkers that are targeted and regulated by metformin in osteoblast differentiation and contribute to understanding the effects of these FDA-approved small-molecule drugs as novel therapeutics for ischemic osteonecrosis.

Highlights

Ischemic necrosis of the femoral head (INFH) can lead to permanent femoral head deformity, severely compromised hip joint longevity, and premature endstage osteoarthritis as early as the third decade of life
Angiopoietin 1 (Ang1) expression was examined by ELISA in U2OS cells [18] after treatment with a library of 821 FDAapproved drugs (Figure 1A and Table 1), and metformin was selected as one of the strongest candidates
To confirm that Ang1 expression was induced by metformin treatment in U2OS and MG63 cells, total proteins were condensed and analyzed by Western blotting of cell culture media from U2OS and MG63 cells treated with or without metformin

Summary

Introduction

Ischemic necrosis of the femoral head (INFH) can lead to permanent femoral head deformity, severely compromised hip joint longevity, and premature endstage osteoarthritis as early as the third decade of life. The therapeutic concepts of angiogenesis and secondary osteogenesis have gained considerable attention in terms of preventing development of femoral head deformities after ischemic osteonecrosis [1]. Several kinds of growth factors have been reported to regulate angiogenesis [2]. Angiopoietin 1 (Ang1) is a well-known angiogenic factor that plays a pivotal role in stimulating and developing new vasculature for bone formation [3, 4]. We reported that a recombinant COMPAng protein, a chimeric form of Ang, facilitates necrotic femoral head repair via enhancement of angiogenesis [5]

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