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Microcomputed tomography staging of bone histolysis in the regenerating mouse digit |
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| Authors: | Paulina D. Ketcham MS Felisha Imholt BS Mingquan Yan MS Hannah M. Smith BS Shabistan Asrar BS Ling Yu PhD Connor P. Dolan PhD Osama Qureshi MS Yu-Lieh Lin PhD Ian Xia BS Patrick C. Hall BS Alyssa R. Falck BS Kirby M. Sherman MS Dana Gaddy PhD Larry J. Suva PhD Ken Muneoka PhD Regina Brunauer PhD Lindsay A. Dawson PhD |
| Affiliation: | 1. Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, USA;2. Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, USA Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon, USA;3. Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, USA DoD-VA Extremity Trauma and Amputation Centre of Excellence, Bethesda, Maryland, USA Department of Surgery, Uniformed Services University of the Health Sciences and Walter Reed National Military Medical Centre, Bethesda, Maryland, USA;4. Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, USA |
| Abstract: | Humans and mice have the ability to regenerate the distal digit tip, the terminal phalanx (P3) in response to amputation. What distinguishes P3 regeneration from regenerative failure is formation of the blastema, a proliferative structure that undergoes morphogenesis to regenerate the amputated tissues. P3 regeneration is characterised by the phases of inflammation, tissue histolysis and expansive bone degradation with simultaneous blastema formation, wound closure and finally blastemal differentiation to restore the amputated structures. While each regenerating digit faithfully progresses through all phases of regeneration, phase progression has traditionally been delineated by time, that is, days postamputation (DPA), yet there is widespread variability in the timing of the individual phases. To diminish variability between digits during tissue histolysis and blastema formation, we have established an in-vivo method using microcomputed tomography (micro CT) scanning to identify five distinct stages of the early regeneration response based on anatomical changes of the digit stump. We report that categorising the initial phases of digit regeneration by stage rather than time greatly diminishes the variability between digits with respect to changes in bone volume and length. Also, stages correlate with the levels of cell proliferation, osteoclast recruitment and osteoprogenitor cell recruitment. Importantly, micro CT staging provides a means to estimate open versus closed digit wounds. We demonstrate two spatially distinct and stage specific bone repair/regeneration responses that occur during P3 regeneration. Collectively, these studies showcase the utility of micro CT imaging to infer the composition of radiolucent soft tissues during P3 blastema formation. Specifically, the staging system identifies the onset of cell proliferation, osteoclastogenesis, osteoprogenitor recruitment, the spatial initiation of de novo bone formation and epidermal closure. |
| Keywords: | Blastema digit intramembranous ossification osteoclasts regeneration |