Skeletal muscle progenitors are sensitive to collagen architectural features of fibril size and cross linking
Skeletal muscle progenitors are sensitive to collagen architectural features of fibril size and cross linking
复制标题
DOI：
10.1152/ajpcell.00065.2021
复制
发表时间：
2021-08-01
影响因子：
5.5
通讯作者：
Smith, Lucas R.
中科院分区：
文献类型：
--
作者：
Hu, Lin-Ya;Mileti, Cassidy J.;Smith, Lucas R.
肌肉干细胞（Muscle Stem Cells，MuSC）是骨骼肌再生能力的关键。然而，在以丰富的胶原和改变的胶原组织为特征的纤维化环境中，MuSC的再生能力降低。MuSC对其细胞外基质环境敏感，但其对胶原结构的反应在很大程度上是未知的。本研究旨在系统地测试底层胶原结构对MuSC功能的影响。胶原蛋白水凝胶工程与不同的架构：胶原蛋白浓度，交联，原纤维的大小，原纤维排列，并与二次谐波产生成像和流变学的变化进行了验证。分别使用EdU测定和免疫标记骨骼肌肌球蛋白表达来评估原代小鼠MuSC和永生成肌细胞（C2C12）的增殖和分化反应。改变胶原蛋白浓度和相应的水凝胶硬度对MuSC增殖或分化没有显著影响。然而，与交联对照相比，MuSC在不形成成熟吡啶啉交联的去端胶原凝胶上的分化增加。此外，MuSC和C2C12成肌细胞在具有较小胶原纤维的凝胶上显示出更大的分化。C2C12成肌细胞的增殖率在具有较小胶原纤维的凝胶上也较高，而MuSC没有显示出显著差异。令人惊讶的是，胶原对齐对肌肉祖细胞功能没有显著影响。这项研究表明，MuSC能够感知其潜在的细胞外基质（ECM）结构，并增强在具有较少胶原交联或较小胶原纤维的基质上的分化。因此，在纤维化肌肉中，靶向交联和原纤维大小而不是胶原蛋白表达可以更有效地支持基于MuSC的再生。
Muscle stem cells (MuSCs) are essential for the robust regenerative capacity of skeletal muscle. However, in fibrotic environments marked by abundant collagen and altered collagen organization, the regenerative capability of MuSCs is diminished. MuSCs are sensitive to their extracellular matrix environment but their response to collagen architecture is largely unknown. The present study aimed to systematically test the effect of underlying collagen structures on MuSC functions. Collagen hydrogels were engineered with varied architectures: collagen concentration, cross linking, fibril size, and fibril alignment, and the changes were validated with second harmonic generation imaging and rheology. Proliferation and differentiation responses of primary mouse MuSCs and immortal myoblasts (C2C12s) were assessed using EdU assays and immunolabeling skeletal muscle myosin expression, respectively. Changing collagen concentration and the corresponding hydrogel stiffness did not have a significant influence on MuSC proliferation or differentiation. However, MuSC differentiation on atelocollagen gels, which do not form mature pyridinoline cross links, was increased compared with the cross-linked control. In addition, MuSCs and C2C12 myoblasts showed greater differentiation on gels with smaller collagen fibrils. Proliferation rates of C2C12 myoblasts were also higher on gels with smaller collagen fibrils, whereas MuSCs did not show a significant difference. Surprisingly, collagen alignment did not have significant effects on muscle progenitor function. This study demonstrates that MuSCs are capable of sensing their underlying extracellular matrix (ECM) structures and enhancing differentiation on substrates with less collagen cross linking or smaller collagen fibrils. Thus, in fibrotic muscle, targeting cross linking and fibril size rather than collagen expression may more effectively support MuSC-based regeneration.