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REVIEW article

Front. Endocrinol.

Sec. Bone Research

Volume 16 - 2025 | doi: 10.3389/fendo.2025.1703129

This article is part of the Research TopicMolecular and Cellular Mechanisms of Bone RemodelingView all 5 articles

Fracture Healing: Cellular Mechanisms and Impact of Parathyroid Hormone and its Analogs

Provisionally accepted
  • 1University of California, San Francisco, San Francisco, United States
  • 2San Francisco VA Health Care System, San Francisco, United States

The final, formatted version of the article will be published soon.

Fractures engender a multimillion dollar medical cost to society with substantial morbidity and mortality for the patients. In long bones fracture repair takes place at 3 distinct sites: intramembranous bone formation along the outer surface of the periosteum, endochondral bone formation bridging the fracture site, and intramedullary bone formation within the marrow at the ends of the fractured bone. Fracture repair occurs in 4 overlapping phases. 1. Hematoma formation and a proinflammatory response that activates the stem cells, 2. initiation of chondrogenesis, osteogenesis, and angiogenesis, 3. mineralization of the soft callus to form the hard callus, 4. remodeling of the callus to regenerate an intact bone. Stem cells in the periosteum, marrow, and overlying muscle supply the cells for the repair process. Parathyroid hormone (PTH) in its 1-34 form (teriparatide) and its analog abaloparatide are promising drugs to promote fracture repair. PTH acts via its receptor (PTHR) which is expressed in essentially all skeletal cells involved in fracture repair. Its anabolic actions are mediated by a number of interacting pathways including cAMP/PKA, Wnt, BMP, IGF1 and the bidirectional signaling of Ephrin B2/Eph B4. Progress in this field will lead to better treatment of fractures especially those slow or fail to heal.

Keywords: Parathyroid hormon, Fracture, skeletal stem cells, cellular signaling, abaloparatide, muscle stem cells

Received: 10 Sep 2025; Accepted: 20 Oct 2025.

Copyright: © 2025 Bikle. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Daniel David Bikle, daniel.bikle@ucsf.edu

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