Activation of HIF by Small Molecule Inhibitors of PHD2 Improves Healing of Cutaneous Wounds and Calvarial Defects
Michael S. Hu, MD, MPH, MS1, Leandra A. Barnes, AB1, Wan Xing Hong, MS1, Min Xie, PhD2, Shibing Tang, PhD2, Robert C. Rennert, MD1, Graham G. Walmsley, BA1, Zeshaan N. Maan, MBBS, MS, MRCS1, Geoffrey C. Gurtner, MD1, Amato J. Giaccia, PhD1, Peter Lorenz, MD1, Sheng Ding, PhD2, Michael T. Longaker, MD, MBA1.
1Stanford University School of Medicine, Stanford, CA, USA, 2UCSF, San Francisco, CA, USA.
Impaired healing of wounds and cranial defects represents a significant clinical challenge. Hypoxia-inducible factor (HIF), master regulator of cellular response to hypoxia, is critical for enhancing the appropriate inflammatory and angiogenic responses that promote the healing of both wounds and skeletal defects. Herein, we examine the effect of small molecule activators of the HIF pathway on both of these processes in vivo.
We generated 25 small molecule analogue inhibitors of PHD2. A high throughput HRE-luciferase assay was performed on NIH 3T3 fibroblasts to identify compounds that would achieve the greatest increase in the HIF pathway. The best three compounds were tested in vivo using a murine model of cutaneous wound and cranial defect healing with splinted 6 mm full thickness excisional wounds and 2 mm frontal and parietal calvarial defects, respectively.
Using the HRE-luciferase assay, we identified compounds GPHD-11, -14, and -15 for upregulating HIF activity 4.01-, 4.38-, and 4.08-fold, respectively (*p<0.05). Full thickness excisional wounds treated with GPHD-11, -14, and -15 completely healed on days 11.5, 11.4, and 11.8, respectively, versus day 13.4 for controls (*p<0.05). Cranial defects in both frontal and parietal regions all healed significantly more with small molecule treatment (*p<0.05).
Our results validate the ability of small molecule analogue inhibitors of PHD2 to activate the HIF pathway in vitro. In vivo, we demonstrate accelerated healing or cutaneous wounds and cranial defects with application of our compounds. With further studies, the small molecule activators of HIF may prove to be a novel therapeutic.
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