DataSheet1_Stretching of porous poly (l-lactide-co-ε-caprolactone) membranes regulates the differentiation of mesenchymal stem cells.docx

Background: Among a variety of biomaterials supporting cell growth for therapeutic applications, poly (l-lactide-co-ε-caprolactone) (PLCL) has been considered as one of the most attractive scaffolds for tissue engineering owing to its superior mechanical strength, biocompatibility, and processibility. Although extensive studies have been conducted on the relationship between the microstructure of polymeric materials and their mechanical properties, the use of the fine-tuned morphology and mechanical strength of PLCL membranes in stem cell differentiation has not yet been studied.
Methods: PLCL membranes were crystallized in a combination of diverse solvent–nonsolvent mixtures, including methanol (MeOH), isopropanol (IPA), chloroform (CF), and distilled water (DW), with different solvent polarities. A PLCL membrane with high mechanical strength induced by limited pore formation was placed in a custom bioreactor mimicking the reproducible physiological microenvironment of the vascular system to promote the differentiation of mesenchymal stem cells (MSCs) into smooth muscle cells (SMCs).
Results: We developed a simple, cost-effective method for fabricating porosity-controlled PLCL membranes based on the crystallization of copolymer chains in a combination of solvents and non-solvents. We confirmed that an increase in the ratio of the non-solvent increased the chain aggregation of PLCL by slow evaporation, leading to improved mechanical properties of the PLCL membrane. Furthermore, we demonstrated that the cyclic stretching of PLCL membranes induced MSC differentiation into SMCs within 10 days of culture.
Conclusion: The combination of solvent and non-solvent casting for PLCL solidification can be used to fabricate mechanically durable polymer membranes for use as mechanosensitive scaffolds for stem cell differentiation.

背景：在用于治疗性应用的多种支持细胞生长的生物材料中，聚（L-乳酸-co-ε-己内酯）(poly (l-lactide-co-ε-caprolactone), PLCL)因优异的机械强度、生物相容性与可加工性，被认为是组织工程领域最具吸引力的支架材料之一。尽管学界已针对聚合物材料微观结构与力学性能间的关联开展了广泛研究，但针对经精细调控形貌与力学性能的PLCL膜应用于干细胞分化的相关研究，目前仍未见于报道。
方法：本研究采用甲醇（methanol, MeOH）、异丙醇（isopropanol, IPA）、氯仿（chloroform, CF）及蒸馏水（distilled water, DW）等极性各异的溶剂-非溶剂混合体系，对PLCL膜进行结晶处理。将通过受限成孔作用获得的高强度PLCL膜置入定制化生物反应器中，该反应器可模拟可复现的血管系统生理微环境，以促进间充质干细胞（mesenchymal stem cells, MSCs）向平滑肌细胞（smooth muscle cells, SMCs）分化。
结果：本研究开发了一种基于共聚物链在溶剂-非溶剂混合体系中结晶行为的孔隙率可控PLCL膜简易制备方法，该方法成本低廉。研究证实，非溶剂比例的提升可通过缓慢蒸发过程促进PLCL链聚集，进而改善PLCL膜的力学性能。此外，本研究还证实，对PLCL膜施加周期性拉伸可在培养10天内诱导MSCs向SMCs分化。
结论：采用溶剂-非溶剂浇铸法固化PLCL，可制备力学性能优异的聚合物膜，用作干细胞分化的机械响应型支架材料。