IGF-1和动态微环境对脂肪干细胞向心肌细胞分化作用的研究

体外组织工程模型中，生物化学和机械信号对心肌再生起着很重要的促进作用，对人胰岛素样生长因子(IGF-1)和三维动态微环境对脂肪干细胞向心肌细胞分化过程中的促进作用进行了研究．带有IGF-1基因的质粒整合到胶原-壳聚糖支架中，脂肪干细胞接种到整合质粒的支架内，未整合质粒的支架作为对照组，心肌细胞培养基作为分化培养基，转瓶生物反应器提供动态微环境．经2周分化培养后，检测质粒在支架内释放及表达情况、细胞在支架内的活性以及心肌功能性蛋白和基因的表达．结果表明：动态微环境能促进质粒DNA的释放和转染；IGF-1可促进脂肪干细胞在胶原-壳聚糖支架内增殖以及向心肌细胞分化；动态微环境可加强IGF-1的促增殖分化作用．因此，IGF-1和动态微环境能独立或相互促进脂肪干细胞在胶原-壳聚糖支架内活性，动态微环境还可强化IGF-1对脂肪干细胞的促分化作用．对体外构建工程化心肌组织进行心肌再生研究有着重要的指导意义．

Differentiation Enhancement of ADSC in Scaffolds With IGF-1 Gene Impregnation Under Dynamic Microenvironment

Biochemical and mechanical signals enabling cardiac regeneration can be elucidated by using in vitro tissue engineering models. It was hypothesized that human insulin-like growth factor-1(IGF-1) and three dimensional dynamic microenvironment could act independently and interactively to enhance the survival and differentiation of adipose tissue-derived stem cells (ADSCs) and hence the construction of engineered cardiac grafts. IGF-1 can be expressed by the ADSCs through genetic modification, which can be conveniently realized by incorporating the relevant genes into the three dimensional scaffold. ADSCs were cultured on three dimensional porous scaffolds with or without plasmid DNA PIRES2-IGF-1 in cardiac media, in dishes and in a spinning flask bioreactor respectively. Cell viability, formation of cardiac like structure, expression of functional proteins, and gene expressions were testified to the cultured constructs on day 14. The results showed that dynamic microenvironment enhanced the release of plasmid DNA; the ADSCs can be transfected by the released plasmid DNA PIRES2-IGF-1 in scaffold; IGF-1 had beneficial effects on the cellular viability and the increase of total protein; and it also increased the expressions of cardiac specific proteins and genes in the grafts. It was also demonstrated that dynamic stirring environment could promote the proliferation of ADSCs. Therefore, IGF-1, expressed by ADSCs transfected by DNA PIRES2-IGF-1 incorporated into scaffold, and hydrodynamic microenvironment can independently and interactively increase cellular viability, and interactively increased the expressions of cardiac specific proteins and genes in the grafts. The results would be useful for developing tissue engineered grafts for myocardial repair.