N-Cadherin is a transmembrane glycoprotein that plays a crucial role in the condensation of mesenchymal cells by enhancing cell–cell interactions during the process of chondrogenesis. The biophysical and biochemical signals can incite enhanced cell–cell contact which ultimately determines the fate of stem cells. The role of cadherin mimetic peptides on the differentiation of mesenchymal stem cells is obscure and must be explored in greater detail. In this study, we designed and synthesized a series of bioactive peptide sequences that mimic the EC-1 domain of the cadherin peptide sequence His-Ala-Val (HAV) motif. These peptide hydrogelators can self-assemble into stable supramolecular nanofibrous hydrogels at physiological pH in the presence of Fmoc-diphenylalanine (2) with tunable mechanical stiffness. Human mesenchymal stem cells (3A6) were encapsulated in N-cadherin mimetic peptide hydrogels to evaluate their role in stem cell differentiation and chondrogenesis. The results suggested that these peptide hydrogels are nontoxic to 3A6 cells and promoted chondrogenesis. Interestingly, 3A6 cells exposed to Fmoc-GGHAVDI (1d) peptide solution showed an enhanced expression level of chondrogenic specific marker collagen-II (Col-II) in comparison with other peptide sequences. In contrast, when 3A6 cells were encapsulated in the hydrogel blend (2/1c), the peptide sequence with flanking amino acid serine exhibited greater material stiffness with enhanced glycosaminoglycan (GAG) distribution and high expression levels of chondrogenic specific markers for the cartilage-specific matrix. This suggests that substrate stiffness and peptide sequences can influence stem cell differentiation. The hydrogel with the HAV motif with greater substrate stiffness (2/1c) can promote the chondrogenic differentiation of human mesenchymal stem cells which can be a promising candidate for 3D cell culture and stem cell-based cartilage regeneration therapies.

中文翻译：

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基质刚度和依赖序列的生物活性肽水凝胶影响人间充质干细胞的软骨分化

N-钙黏着蛋白是一种跨膜糖蛋白，通过增强软骨形成过程中的细胞间相互作用，在间充质细胞的凝缩中起关键作用。生物物理和生化信号可以促进细胞间的接触，最终决定干细胞的命运。钙粘蛋白模拟肽在间充质干细胞分化中的作用是模糊的，必须更详细地探讨。在这项研究中，我们设计并合成了一系列生物活性肽序列，这些序列可模拟钙粘蛋白肽序列His-Ala-Val（HAV）基序的EC-1域。这些肽水凝胶化剂可以在Fmoc-二苯丙氨酸存在的情况下，在生理pH下自组装成稳定的超分子纳米纤维水凝胶（2）具有可调节的机械刚度。将人间充质干细胞（3A6）封装在N-钙粘蛋白模拟肽水凝胶中，以评估其在干细胞分化和软骨形成中的作用。结果表明这些肽水凝胶对3A6细胞无毒，并促进了软骨形成。有趣的是，与其他肽序列相比，暴露于Fmoc-GGHAVDI（1d）肽溶液的3A6细胞显示出软骨形成特异性标记胶原II（Col-II）的增强表达水平。相反，将3A6细胞封装在水凝胶混合物中（2 / 1c），具有侧翼氨基酸丝氨酸的肽序列显示出更高的材料刚度，增强了糖胺聚糖（GAG）分布，并且软骨特异性基质的软骨生成特异性标记物表达水平高。这表明底物的硬度和肽序列可以影响干细胞的分化。具有更高底物刚度（2 / 1c）的HAV主题的水凝胶可以促进人间充质干细胞的软骨分化，这可能是3D细胞培养和基于干细胞的软骨再生疗法的有希望的候选者。