Inhibition of Hif1α prevents both trauma-induced and genetic heterotopic ossification

Proc Natl Acad Sci U S A. 2016 Jan 19;113(3):E338-47. doi: 10.1073/pnas.1515397113. Epub 2015 Dec 31.


Pathologic extraskeletal bone formation, or heterotopic ossification (HO), occurs following mechanical trauma, burns, orthopedic operations, and in patients with hyperactivating mutations of the type I bone morphogenetic protein receptor ACVR1 (Activin type 1 receptor). Extraskeletal bone forms through an endochondral process with a cartilage intermediary prompting the hypothesis that hypoxic signaling present during cartilage formation drives HO development and that HO precursor cells derive from a mesenchymal lineage as defined by Paired related homeobox 1 (Prx). Here we demonstrate that Hypoxia inducible factor-1α (Hif1α), a key mediator of cellular adaptation to hypoxia, is highly expressed and active in three separate mouse models: trauma-induced, genetic, and a hybrid model of genetic and trauma-induced HO. In each of these models, Hif1α expression coincides with the expression of master transcription factor of cartilage, Sox9 [(sex determining region Y)-box 9]. Pharmacologic inhibition of Hif1α using PX-478 or rapamycin significantly decreased or inhibited extraskeletal bone formation. Importantly, de novo soft-tissue HO was eliminated or significantly diminished in treated mice. Lineage-tracing mice demonstrate that cells forming HO belong to the Prx lineage. Burn/tenotomy performed in lineage-specific Hif1α knockout mice (Prx-Cre/Hif1α(fl:fl)) resulted in substantially decreased HO, and again lack of de novo soft-tissue HO. Genetic loss of Hif1α in mesenchymal cells marked by Prx-cre prevents the formation of the mesenchymal condensations as shown by routine histology and immunostaining for Sox9 and PDGFRα. Pharmacologic inhibition of Hif1α had a similar effect on mesenchymal condensation development. Our findings indicate that Hif1α represents a promising target to prevent and treat pathologic extraskeletal bone.

Keywords: HIF1α; Prx; cartilage; heterotopic ossification; mesenchymal condensation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Activin Receptors, Type I / metabolism
  • Adipose Tissue / drug effects
  • Adipose Tissue / metabolism
  • Animals
  • Burns / complications
  • Burns / genetics
  • Chondrogenesis / drug effects
  • Chondrogenesis / genetics
  • Disease Models, Animal
  • Gene Regulatory Networks / drug effects
  • Humans
  • Hypoxia-Inducible Factor 1, alpha Subunit / antagonists & inhibitors*
  • Hypoxia-Inducible Factor 1, alpha Subunit / genetics
  • Hypoxia-Inducible Factor 1, alpha Subunit / metabolism
  • Integrases / metabolism
  • Luminescent Measurements
  • Mesenchymal Stem Cells / drug effects
  • Mice, Knockout
  • Models, Biological
  • Mustard Compounds / pharmacology
  • Ossification, Heterotopic / diagnostic imaging
  • Ossification, Heterotopic / drug therapy
  • Ossification, Heterotopic / genetics*
  • Ossification, Heterotopic / prevention & control*
  • Phenylpropionates / pharmacology
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Receptor, Platelet-Derived Growth Factor alpha / metabolism
  • SOX9 Transcription Factor / metabolism
  • Signal Transduction / drug effects
  • Sirolimus / pharmacology
  • Tendons / drug effects
  • Tendons / pathology
  • Tendons / surgery
  • Tenotomy
  • Up-Regulation / drug effects
  • Wound Healing / drug effects
  • Wounds and Injuries / complications*
  • Wounds and Injuries / pathology
  • X-Ray Microtomography


  • 2-amino-3-(4'-N,N-bis(2-chloroethyl)amino)phenylpropionic acid N-oxide
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Mustard Compounds
  • Phenylpropionates
  • RNA, Messenger
  • SOX9 Transcription Factor
  • Receptor, Platelet-Derived Growth Factor alpha
  • Activin Receptors, Type I
  • Cre recombinase
  • Integrases
  • Sirolimus