BACKGROUND Biocompatible hydrogel systems with tunable mechanical properties have been reported to influence the behavior and differentiation of mesenchymal stem cells (MSCs). OBJECTIVE To develop a functionalized hydrogel system with well-defined chemical structures and tunable mechanical property for regulation of stem cell differentiation. METHODS An in situ-forming hydrogel system is developed by crosslinking vinyl sulfone functionalized polyamidoamine (PAMAM) dendrimer and multi-armed thiolated polyethylene glycol (PEG) through a thiol-ene Michael addition in aqueous conditions. The viability and differentiation of MSCs in hydrogels of different stiffness are conducted for 21 days under corresponding induction media. RESULTS MSCs are viable in synthesized hydrogels after 48 hours of culture. By varying the concentrations of PAMAM dendrimer and PEG, hydrogels of different gelation time and stiffness are achieved. The MSC differentiation indicates that more osteogenic differentiation is observed in hard gel (5,663 Pa) and more adipogenic differentiation is observed in soft gel (77 Pa) in addition to the differentiation caused by each individual induction media during the process of culture. CONCLUSIONS A biocompatible in situ-forming hydrogel system is successfully synthesized. This hydrogel system has shown influences on differentiation of MSCs and may potentially be important in developing therapeutic strategies in medical applications.

中文翻译：

---

聚酰胺酰胺树状聚合物-PEG水凝胶及其对间充质干细胞分化的力学性能。

背景技术已经报道了具有可调机械性能的生物相容性水凝胶系统影响间充质干细胞（MSC）的行为和分化。目的开发具有明确化学结构和可调机械性能的功能化水凝胶体系，以调节干细胞分化。方法通过在水性条件下通过硫醇-烯键迈克尔加成反应，将乙烯基砜官能化的聚酰胺胺（PAMAM）树枝状聚合物和多臂硫醇化聚乙二醇（PEG）交联，开发出一种原位形成的水凝胶体系。在相应的诱导培养基下，在不同刚度的水凝胶中，MSCs的活力和分化进行了21天。结果培养48小时后，MSC在合成的水凝胶中是可行的。通过改变PAMAM树状聚合物和PEG的浓度，可以获得不同胶凝时间和硬度的水凝胶。MSC的分化表明，除了在培养过程中各个诱导培养基引起的分化之外，在硬凝胶（5,663 Pa）中观察到更多的成骨分化，在软凝胶（77 Pa）中观察到更多的成脂分化。结论成功合成了生物相容性原位形成的水凝胶系统。该水凝胶系统已显示出对MSC分化的影响，并且在开发医学应用的治疗策略中可能具有重要意义。除了在培养过程中由各个诱导培养基引起的分化外，在软凝胶（77 Pa）中还观察到了更多的成脂分化（77 Pa）。结论成功合成了生物相容性原位形成的水凝胶系统。该水凝胶系统已显示出对MSC分化的影响，并且在开发医学应用的治疗策略中可能具有重要意义。除了在培养过程中由各个诱导培养基引起的分化外，在软凝胶（77 Pa）中还观察到了更多的成脂分化（77 Pa）。结论成功合成了生物相容性原位形成的水凝胶系统。该水凝胶系统已显示出对MSC分化的影响，并且在开发医学应用的治疗策略中可能具有重要意义。