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Abstract 25: HIF-2a Critically Regulates Metabolism and Homeostasis in Long Bones

Plastic and Reconstructive Surgery – Global Open: April 2016 - Volume 4 - Issue 4S - p 47
doi: 10.1097/01.GOX.0000488957.24409.f8
PRS PSRC Podium Proofs 2016

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Kavitha Ranganathan, MD, Michael Sorkin, MD, Christophe Merceron, PhD, Angela Yao, PhD, Laura Mangiavini, MD, Amato Giaccia, PhD, Shailesh Agarwal, MD, Benjamin Levi, MD, Ernestina Schipani, MD, PhD

From the University of Michigan, Ann Arbor, Mich.

PURPOSE: Hypoxia inducible factor-1α (HIF-1α) plays a critical role in angiogenesis and regulation of osteoblast metabolism. Similarly, HIF-2α is expressed in cells of the osteoblast lineage; however, its exact role in bone formation and homeostasis remains to be determined.

METHODS: We generated a novel gain-of-function mouse model in which PRX-1Cre transgenic mice were crossed to HIF-2α dPAf/f. In vivo analysis was conducted at 6 and 12 weeks of age, respectively, by nano computed tomography, routine histology, and histomorphometry. Moreover, bone marrow stromal cells overexpressing HIF-2α were subjected to microarray analysis.

RESULTS: HIF-2a overexpressing mice demonstrated distinct morphologic changes in long bone size and shape. Although trabecular density was increased in mutant mice on nano computed tomography, this was highly disorganized with thinner trabeculae compared with controls. Furthermore, increased number of cartilage remnants was observed in mutant mice suggesting elevated resorption because of altered osteoclast function. This may be contributed by upregulation of lysyl oxidase and downregulation of metalloproteinase 13 in mutant cells as seen on microarray analysis.

CONCLUSIONS: We demonstrate that overexpression of HIF-2α affects the overall size, shape, and composition of long bones. Moreover, HIF-2α critically modulates bone metabolism and may alter the quality of matrix deposited by osteoblasts. These findings help define the role of HIF-2α in osteogenesis and may enable strategies in the treatment of patients with disorders of bone development.

© 2016 American Society of Plastic Surgeons