Pore size is generally small in nanofibrous scaffolds prepared by electrospinning polymeric solutions. Increase of scaffold thickness leads to decrease in pore size, causing impediment to cell infiltration into the scaffolds during tissue engineering. In contrast, comparatively larger pore size can be realized in microfibrous scaffolds prepared from polymeric solutions at higher concentrations. Further, microfibrous scaffolds are conducive to infiltration of reparative M2 phenotype macrophages during in vivo/in situ tissue engineering. However, rise of mechanical properties of a fibrous scaffold with the increase of polymer concentration may limit the functionality of a scaffold-based, tissue-engineered heart valve. In this study, we developed microfibrous scaffolds from 14%, 16% and 18% (wt/v) polycaprolactone (PCL) polymer solutions prepared with chloroform solvent. Porcine valvular interstitial cells were cultured in the scaffolds for 14 d to investigate the effect of microfibers prepared with different PCL concentrations on the seeded cells. Further, fresh microfibrous scaffolds were implanted subcutaneously in a rat model for two months to investigate the effect of microfibers on infiltrated cells. Cell proliferation, and its morphologies, gene expression and deposition of different extracellular matrix proteins in the in vitro study were characterized. During the in vivo study, we characterized cell infiltration, and myofibroblast and M1/M2 phenotypes expression of the infiltrated cells. Among different PCL concentrations, microfibrous scaffolds from 14% solution were suitable for heart valve tissue engineering for their sufficient pore size and low but adequate tensile properties, which promoted cell adhesion to and proliferation in the scaffolds, and effective gene expression and extracellular matrix deposition by the cells in vitro. They also encouraged the cells in vivo for their infiltration and effective gene expression, including M2 phenotype expression.

中文翻译：

---

用于心脏瓣膜组织工程的聚己内酯纤维支架的优化。

通过静电纺丝聚合物溶液制备的纳米纤维支架的孔径通常很小。支架厚度的增加导致孔径的减小，从而在组织工程期间阻碍细胞向支架中的浸润。相反，在由较高浓度的聚合物溶液制备的微纤维支架中可以实现相对较大的孔径。此外，微纤维支架在体内/原位组织工程过程中有利于修复性M2表型巨噬细胞的浸润。然而，随着聚合物浓度的增加，纤维支架的机械性能的提高可能会限制基于支架的，组织工程化的心脏瓣膜的功能。在这项研究中，我们开发了14％的微纤维支架，用氯仿溶剂制备的16％和18％（wt / v）聚己内酯（PCL）聚合物溶液。猪瓣膜间质细胞在支架中培养14天，以研究用不同PCL浓度制备的微纤维对种子细胞的影响。此外，将新鲜的微纤维支架皮下植入大鼠模型中两个月，以研究微纤维对浸润细胞的影响。在体外研究中表征了细胞增殖，其形态，基因表达和不同细胞外基质蛋白的沉积。在体内研究期间，我们表征了细胞浸润以及浸润细胞的成纤维细胞和M1 / M2表型表达。在不同浓度的PCL中，14％溶液中的微纤维支架具有足够的孔径和低但足够的拉伸性能，可促进细胞粘附于支架并在支架中增殖，以及有效的基因表达和体外细胞外基质沉积，因此适用于心脏瓣膜组织工程。他们还鼓励体内细胞的浸润和有效的基因表达，包括M2表型表达。