Osteomacs and Bone Regeneration
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Purpose of Review
Mounting evidence supporting the critical contribution of macrophages, in particular osteal macrophages, to bone regeneration is reviewed. We specifically examine the potential role of macrophages in the basic multicellular units coordinating lifelong bone regeneration via remodelling and bone regeneration in response to injury. We review and discuss the distinctions between macrophage and osteoclast contributions to bone homeostasis, particularly the dichotomous role of the colony-stimulating factor 1—colony-stimulating factor 1 receptor axis.
The impact of inflammation associated with aging and other hallmarks of aging, including senescence, on macrophage function is addressed in the context of osteoporosis and delayed fracture repair. Resident macrophages versus recruited macrophage contributions to fracture healing are also discussed.
We identify some of the remaining knowledge gaps that will need to be closed in order to maximise benefits from therapeutically modulating or mimicking the function of macrophages to improve bone health and regeneration over a lifetime.
KeywordsMacrophages Bone regeneration Fracture repair Senescence Inflammaging Osteoporosis
This work was supported by the Mater Foundation and an Australian and New Zealand Bone and Mineral Society Gap Fellowship to ARP.
Dr. Andy C. Wu contributed to experiments in Fig. 1.
Compliance with Ethical Standards
Conflict of Interest
Lena Batoon, Allison Pettit, Liza Jane Raggatt and Susan Millard declare no conflict of interest.
Human and Animal Rights and Informed Consent
All reported studies/experiments with human or animal subjects performed by the authors comply with all applicable ethical standards (including the Helsinki Declaration and its amendments, institutional/national research committee standards and international/national/institutional guidelines). Animal experiments were approved by The University of Queensland Health Sciences Ethics Committee and performed in accordance with the Australian Code of Practice for the Care and Use of Animals for Scientific Purposes.
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