Mesenchymal stromal cells contract collagen more efficiently than dermal fibroblasts: Implications for cytotherapy

BackgroundStem cell therapy is the next generation a well-established technique. Cell therapy with mesenchymal stem cells (MSC) has been demonstrated to enhance wound healing in diabetic mice, at least partly due to improved growth factor production. However, it is unclear whether MSC can biomechanically affect wound closure. Utilizing the well-established cell-populated collagen gel contraction model we investigated the interactions between MSC and the extracellular matrix.MethodsMurine fetal liver-derived Mesenchymal Stem Cells (MSCs) or fetal Dermal Fibroblasts (DFs) were cultured in cell–populated collagen gels (CPCGs). The effect of cell density, conditioned media, growth factors (TGF-B1, FGF, PDGF-BB), cytoskeletal disruptors (colchicine, cytochalasin-D), and relative hypoxia on gel contraction were evaluated. Finally, we also measured the expression of integrin receptors and some growth factors by MSCs within the contracting gels.ResultsOur results show that at different densities, MSCs induced a higher gel contraction compared to DFs. Higher cell density resulted in faster and more complete contraction of CPCGs. Cytoskeletal inhibitors either inhibited or prevented MSC-mediated contraction in a dose dependent fashion. Growth factors, conditioned media from both MSC and DF, and hypoxia all influenced CPCG contraction.DiscussionThe results suggest that MSCs are capable of directly contributing to wound closure through matrix contraction, and they are more effective than DF. In addition, this study demonstrates the importance of how other factors such as cell concentration, cytokines, and oxygen tension can provide potential modulation of therapies to correct wound healing impairments.背景：干细胞疗法是一项成熟的下一代治疗技术。间充质干细胞（mesenchymal stem cells, MSC）疗法已被证实可促进糖尿病小鼠的伤口愈合，这一效应至少部分源于生长因子生成的增强。然而，目前尚不明确间充质干细胞是否可通过生物力学途径影响伤口闭合。本研究采用成熟的细胞填充胶原凝胶收缩模型，探究了间充质干细胞与细胞外基质之间的相互作用。 方法：提取小鼠胎肝来源的间充质干细胞（MSCs）或胎皮肤成纤维细胞（DFs），将其接种于细胞填充胶原凝胶（cell-populated collagen gels, CPCGs）中进行体外培养。本研究评估了细胞密度、条件培养基、生长因子（TGF-β1、FGF、PDGF-BB）、细胞骨架干扰剂（秋水仙素、细胞松弛素D）以及相对低氧环境对凝胶收缩的影响。最后，本研究还检测了收缩凝胶中间充质干细胞的整合素受体与部分生长因子的表达水平。 结果：本研究结果显示，在不同接种密度下，间充质干细胞诱导的凝胶收缩程度均高于胎皮肤成纤维细胞；更高的细胞接种密度可使细胞填充胶原凝胶的收缩速度更快、收缩程度更完全。细胞骨架抑制剂可通过剂量依赖性方式，抑制或阻断间充质干细胞介导的凝胶收缩。生长因子、间充质干细胞与胎皮肤成纤维细胞的条件培养基，以及低氧环境均会对细胞填充胶原凝胶的收缩产生影响。 讨论：本研究结果表明，间充质干细胞可通过基质收缩直接促进伤口闭合，且其效果优于胎皮肤成纤维细胞。此外，本研究证实，细胞浓度、细胞因子、氧分压等多种因素可通过调控疗法改善伤口愈合障碍，这一发现具有重要的研究价值。