Ketcham Paulina D, Imholt Felisha, Yan Mingquan, Smith Hannah M, Asrar Shabistan, Yu Ling, Dolan Connor P, Qureshi Osama, Lin Yu-Lieh, Xia Ian, Hall Patrick C, Falck Alyssa R, Sherman Kirby M, Gaddy Dana, Suva Larry J, Muneoka Ken, Brunauer Regina, Dawson Lindsay A
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.
Wound Repair Regen. 2023 Jan;31(1):17-27. doi: 10.1111/wrr.13054. Epub 2022 Oct 4.
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.
人类和小鼠能够在截肢后再生远端指尖，即末节指骨（P3）。P3再生与再生失败的区别在于芽基的形成，芽基是一种增殖性结构，经过形态发生过程来再生被截肢的组织。P3再生的特征包括炎症期、组织溶解期和扩展性骨降解期，同时伴有芽基形成、伤口闭合，最终芽基分化以恢复被截肢的结构。虽然每个再生的手指都忠实地经历再生的所有阶段，但传统上阶段进展是按时间来划分的，即截肢后天数（DPA），然而各个阶段的时间存在广泛的变异性。为了减少组织溶解和芽基形成过程中手指之间的变异性，我们建立了一种体内方法，使用微型计算机断层扫描（micro CT）扫描，根据指残端的解剖学变化来识别早期再生反应的五个不同阶段。我们报告称，按阶段而非时间对手指再生的初始阶段进行分类，能大大减少手指在骨体积和长度变化方面的变异性。此外，阶段与细胞增殖、破骨细胞募集和成骨祖细胞募集的水平相关。重要的是，micro CT分期提供了一种估计手指伤口开放与闭合状态的方法。我们展示了在P3再生过程中发生的两种空间上不同且阶段特异性的骨修复/再生反应。总的来说，这些研究展示了micro CT成像在推断P3芽基形成过程中透光软组织组成方面的实用性。具体而言，分期系统确定了细胞增殖、破骨细胞生成、成骨祖细胞募集的起始，以及新生骨形成和表皮闭合的空间起始。
