中文摘要：

目的：探讨小分子水凝胶对大鼠骨髓间充质干细胞（MSCs）心肌分化过程中早期分化基因Desmin和α-actin的表达影响。方法：流式细胞仪检测鉴定P9MSCs细胞表面标记物，分别应用10μmol／L5-aza（5．aza组）、小分子水凝胶＋5-aza（水凝胶组）对第9代MSCs进行联合诱导24h，诱导4周后，QRT-PCR和Western—blotting法检测Desmin、α—actinmRNA及蛋白的表达。结果：第9代MSCsCD44阳性表达、CD34阴性表达；诱导4周后，5-aza组细胞难以形成球状细胞团，细胞容易脱落，凋亡及死亡细胞较多；水凝胶组细胞死亡少，数量较诱导前增多。细胞之间的分支连接紧密，有聚集生长的趋势，形成球状细胞团块，个别细胞内形成类肌管状结构。5-aza组和水凝胶组心肌早期分化基因Desmin、α-actin均有阳性表达．水凝胶组mRNA及蛋白表达水平均较5-aza组明显增强（P〈0．05）。结论：小分子水凝胶可作为细胞的三维培养支架．有利于MSCs生长，具有促进5-aza诱导的MSCs向心肌样细胞分化的作用。

英文摘要：

Objective： To study the effects of small molecular hydrogel （SMH） on the expression of Desmin, an early-phase differentiation-associated gene, and α-actin during differentiation of bone marrow mesenehymal stem cell （MSC） into cardiomyocytes. Methods ： Flow cytometry was employed to determine the P9 MSCs surface markers. Following passage for nine cycles, the MSCs were subjected to incubation with 5- azacytidine （5-aza） at 10 μmol/L alone or in combination with SMH at 1% for 24 hours. This was followed by quantitative real-time polymerase chain reaction for assessment of Desmin and a-actin mRNA expression and Western blotting for protein expression at week 4. Results： The MSCs of the ninth passage tested by positively to CIM4 and negatively to CD34. Following a 4-week incubation, the cells treated with 5-aza were characterized by globular cluster formation with increased susceptibility to apoptosis and cell death, whilst the cells treated with the addition of SMHS were noted as having reduced number of death yet increased cell count compared with baseline level, presence of tight junction between neighboring cells, a tendency of aggregated growth and formation of globular cluster with cytoplasmic sarcotubunoid structure in a minority of cells. Cells tested positively to Desmin and α-actin mRNA were noted in both groups. However, the addition of SMH resulted in remarkably increased Desmin and α-actin mRNA and protein expression （both P 〈0.05 ）. Conclusion：The SMH, acting as the three-dimensional folding for cell culture, may facilitate cell growth and induce differentiation of MSCs into eardiomyocytes following incubation with 5-aza.