05),Sca-1+细胞比例显著高于对照组(P<0.05),但与SB431542组比较均显著降低(P0.05)。结论利用RA可以促进ES和i PS向MSC样细胞分化,分化方法较为简单,分化周期较短,为多能干细胞向MSC样细胞的分化提供了一定的方法基础。
包括人类在内的哺乳动物仅具有极为有限的再生能力,然而以蝾螈、非洲爪蟾等为代表的两栖类动物则能在特定时期完全修复缺损的组织器官。该文对近年来两栖类动物组织器官再生的细胞及分子机制研究作一综述,并以诱导成体爪蟾断肢再生为例,探讨诱导器官再生的研究策略。
AIM:To explore ex vivo the role of bone morphogenetic protein-4(BMP-4) and transforming growth factorbeta1(TGF-β1) in acute valvular response to fluid shear stress(FSS) abnormalities.METHODS:Porcine valve leaflets were subjected ex vivo to physiologic FSS,supra-physiologic FSS

magnitude at normal frequency and supra-physiologic FSS frequency at normal magnitude for 48 h in a double-sided cone-and-plate selleck bioreactor filled with standard culture medium. The role of BMP-4 and TGF-β1 in the valvular response was investigated by promoting or inhibiting the downstream action of those cytokines via culture medium supplementation with BMP-4 或者 or the BMP antagonist noggin,and TGF-β1 or the TGF-β1 inhibitor SB-431542,respectively.

Fresh porcine leaflets were used as controls. Each experimental group consisted of six leaflet samples. Immunostaining and immunoblotting were performed to assess endothelial activation in terms of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 expressions,paracrine signaling in terms of BMP-4 and TGF-β1 expressions and extracellular matrix(ECM) remodeling in terms of cathepsin L,cathepsin S,metalloproteinases(MMP)-2 and MMP-9 expressions. Immunostained images were quantified by normalizing the intensities of positively stained regions by the number of cells in each image while immunoblots

were quantified by densitometry. R E S U LT S :Regardless of the culture medium,physiologic FSS maintained valvular homeostasis. Tissue exposure to supra-physiologic FSS magnitude in standard SB431542购买 medium stimulated paracrine signaling(TGF-β1:467% ± 22% vs 100% ± 6% in freshcontrols,BMP-4:258% ± 22% vs 100% ± 4% in fresh controls; P < 0.05) and ECM degradation(MMP-2:941% ± 90% vs 100% ± 19% in fresh controls,MMP-9:1219% ± 190% vs 100% ± 16% in fresh controls,cathepsin L:1187% ± 175% vs 100% ± 12% in fresh controls,cathepsin S:603% ± 88% vs 100% ± 13% in fresh controls; P < 0.05),while BMP-4 supplementation also promoted fibrosa activation and TGF-β1 inhibition reduced MMP-9 expression to the native tissue level(MMP-9:308% ± 153% with TGF-β1 inhibition vs 100% ± 16% in fresh control; P > 0.05). Supra-physiologic FSS frequency had no effect on endothelial activation and paracrine signaling regardless of the culture medium but TGF-β1 silencing attenuated FSS-induced ECM degradation via MMP-9 downregulation(MMP-9:302% ± 182% vs 100% ± 42% in fresh controls; P > 0.05).CONCLUSION:Valvular tissue is sensitive to FSS abnormalities. The TGF-β1 inhibitor SB-431542 is a potential candidate molecule for attenuating the effects of FSS abnormalities on valvular remodeling.