1 McGowan Institute for Regenerative Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania.
2 Department of Bioengineering, University of Pittsburgh , Pittsburgh, Pennsylvania.
Tissue Eng Part A. 2018 Jan;24(1-2):34-46. doi: 10.1089/ten.TEA.2017.0011. Epub 2017 Apr 19.
Mounting evidence suggests that site-appropriate loading of implanted extracellular matrix (ECM) bioscaffolds and the surrounding microenvironment is an important tissue remodeling determinant, although the role at the cellular level in ECM-mediated skeletal muscle remodeling remains unknown. This study evaluates crosstalk between progenitor cells and macrophages during mechanical loading in ECM-mediated skeletal muscle repair. Myoblasts were exposed to solubilized ECM bioscaffolds and were mechanically loaded at 10% strain, 1 Hz for 5 h. Conditioned media was collected and applied to bone marrow-derived macrophages followed by immunolabeling for proinflammatory M1-like markers and proremodeling M2-like markers. Macrophages were subjected to the same loading protocol and their secreted products were collected for myoblast migration, proliferation, and differentiation analysis. A mouse hind limb unloading volumetric muscle loss model was used to evaluate the effect of loading upon the skeletal muscle microenvironment after ECM implantation. Animals were sacrificed at 14 or 180 days. Isometric torque production was tested and tissue sections were immunolabeled for macrophage phenotype and muscle fiber content. Results show that loading augments the ability of myoblasts to promote an M2-like macrophage phenotype following exposure to ECM bioscaffolds. Mechanically loaded macrophages promote myoblast chemotaxis and differentiation. Lack of weight bearing impaired muscle remodeling as indicated by Masson's Trichrome stain. Isometric torque was significantly increased following ECM implantation when compared to controls, a response not present in the hind limb-unloaded group. This work provides an important mechanistic insight of the effects of rehabilitation upon ECM-mediated remodeling and could have broader implications in clinical practice, advocating multidisciplinary approaches to regenerative medicine, emphasizing rehabilitation.
越来越多的证据表明，植入细胞外基质 (ECM) 生物支架和周围微环境的适当部位加载是组织重塑的重要决定因素，尽管 ECM 介导的骨骼肌重塑的细胞水平作用尚不清楚。本研究评估了祖细胞和巨噬细胞在 ECM 介导的骨骼肌修复过程中的机械加载中的相互作用。将成肌细胞暴露于可溶解的 ECM 生物支架中，并在 10%应变、1 Hz 下机械加载 5 小时。收集条件培养基并应用于骨髓来源的巨噬细胞，然后用促炎 M1 样标志物和促重塑 M2 样标志物进行免疫标记。对巨噬细胞进行相同的加载方案，并收集其分泌产物用于成肌细胞迁移、增殖和分化分析。使用小鼠后肢去负荷体积性肌肉损失模型来评估 ECM 植入后加载对骨骼肌微环境的影响。动物在 14 或 180 天处死。进行等长扭矩产生测试，并对组织切片进行免疫标记以检测巨噬细胞表型和肌纤维含量。结果表明，加载增强了成肌细胞在暴露于 ECM 生物支架后促进 M2 样巨噬细胞表型的能力。机械加载的巨噬细胞促进成肌细胞趋化和分化。缺乏负重会导致肌肉重塑受损，如 Masson 三色染色所示。与对照组相比，ECM 植入后等长扭矩显著增加，而在下肢去负荷组则没有这种反应。这项工作提供了康复对 ECM 介导的重塑影响的重要机制见解，并可能在临床实践中具有更广泛的意义，提倡再生医学的多学科方法，强调康复。
