Gata4, Tbx5 and Baf60c induce differentiation of adipose tissue-derived mesenchymal stem cells into beating cardiomyocytes

The adipose tissue-derived mesenchymal stem cells (ADMSCs) are extensively utilized in tissue engineering, regenerative medicine and cell therapy. ADMSCs can differentiate into cardiomyocytes, and it has been shown that over-expression of a cocktail of factors can induce ectopic heart formation and program cardiogenesis in ESCs. However, which genes are responsible for differentiation of ADMSCs into beating cardiomyocyte-like cells remains unknown. In this study we have shown that the combination of Gata4, Tbx5 and Baf60c is sufficient for inducing ADMSCs to form cardiomyocytes. It also appears that, while Gata4 and Baf60c are key inducers of myocardial differentiation, Tbx5 is essential for the ability of cardiac cells to contract. These findings provide additional experimental references for myocardial tissue engineering in the emerging field of cell-based therapy of heart diseases.     

Tbx18 能使兔脂肪干细胞向心肌样细胞分化

目的:研究Tbx18是否能成功转染脂肪干细胞并使脂肪干细胞向心肌细胞分化。方法:分离培养来源于日本大耳兔腹股沟部脂肪的兔脂肪干细胞,用搭载有Tbx18的腺病毒载体转染脂肪干细胞,诱导分化后检测向心肌细胞的分化情况,同时将转染了含GFP的腺病毒组与未转染组作为对照。采用用流式细胞仪检测转染效率,采用免疫荧光法检测平滑肌肌动蛋白α-SMA,采用实时定量PCR法检测兔肌钙蛋白TNNT2的表达。结果:转染后荧光显微镜下可观察到荧光表达,且持续时间较长。流式细胞仪检测转染效率为70%左右;诱导分化后,脂肪干细胞内出现了α-SMA和TNNT2的表达。结论:Tbx18可成功转染入脂肪干细胞,且能在细胞内稳定表达;Tbx18可诱导脂肪干细胞向心肌样细胞分化。     

基因谱系示踪揭示小鼠Tbx18+肾脏间质祖细胞分化为输尿管平滑肌

本文旨在研究Tbx18+肾脏间质祖细胞分化为输尿管平滑肌细胞的命运及转录因子Tbx18在小鼠输尿管平滑肌发育形成中起到的作用．实验建立Tbx18:Cre/R26REYFP和Tbx18:Cre/R26RLacZ两种谱系示踪系统和Tbx18:Cre/Cre 敲除模型．该示踪模型通过cre重组酶的表达能有效地示踪Tbx18+肾脏间质祖细胞在泌尿系统的发育命运．通过免疫荧光染色和X-gal染色,同时发现Tbx18+肾脏间质祖细胞可分化为输尿管平滑肌细胞,但不分化为输尿管移行上皮细胞．在Tbx18:Cre/Cre基因突变模型中,泌尿系统出现明显的肾积水和输尿管积水,肾盏、肾盂扩张,输尿管明显缩短和扩张．实验结果揭示,Tbx18+ 肾脏间质祖细胞可以分化为输尿管平滑肌细胞,且转录因子Tbx18在哺乳动物输尿管平滑肌的发育中起到重要的作用．     

基因谱系示踪技术揭示小鼠Tbx18+心脏祖细胞向心系细胞分化的潜能

心脏祖细胞(cardiac progenitor cells,CPCs)的研究对阐明先天性心脏病的机制及治疗心血管疾病具有重要意义.哺乳动物的心脏组织由多种不同CPCs分化形成.转录因子Tbx18在发育中的心外膜中表达,对心脏的发育形成起重要的调节作用.为了在组织及活体细胞水平检测和阐明Tbx18+CPC的分化潜能,应用Cre-LoxP系统建立Tbx18+CPCs基因命运谱系示踪模型:Tbx18-Cre/Rosa26R-EYFP和Tbx18-Cre/Rosa26R-LacZ双杂合基因敲入小鼠.该双杂合基因敲入小鼠通过Cre的表达能有效地示踪Tbx18+细胞在胚胎和成年小鼠中的分化命运.Tbx18-Cre/Rosa26R-EYFP双杂合小鼠心脏能非常容易地利用流式细胞分选系统(FACS)分离出YFP+细胞,也可在倒置共聚焦显微镜下观察.应用X-gal染色分析其表达模式,揭示Tbx18命运谱系参与心房肌、室间隔、心室肌、冠状动脉、瓣膜等的形成.应用免疫荧光技术初步揭示Tbx18+CPCs向心脏肌钙蛋白T(cTNT)阳性心肌细胞和平滑肌肌球蛋白重链11(MYH11)阳性血管平滑肌细胞分化的潜能.心脏是一个由多种肌肉和非肌肉组织细胞构成的复杂器官.推测Tbx18可能在心脏祖细胞向肌源性细胞分化的信号通路中起重要调节作用.在上述研究中应用基因谱系示踪技术,验证Tbx18可作为一类CPCs的标志,为更深入揭示心脏祖细胞向心系细胞的分化潜能打下基础.     

Isoproterenol directs hair follicle-associated pluripotent (HAP) stem cells to differentiate in vitro to cardiac muscle cells which can be induced to form beating heart-muscle tissue sheets

Nestin-expressing hair-follicle-associated pluripotent (HAP) stem cells are located in the bulge area of the follicle. Previous studies have shown that HAP stem cells can differentiate to neurons, glia, keratinocytes, smooth muscle cells, and melanocytes in vitro. HAP stem cells effected nerve and spinal cord regeneration in mouse models. Recently, we demonstrated that HAP stem cells differentiated to beating cardiac muscle cells. The differentiation potential to cardiac muscle cells was greatest in the upper part of the follicle. The beat rate of the cardiac muscle cells was stimulated by isoproterenol. In the present study, we observed that isoproterenol directs HAP stem cells to differentiate to cardiac muscle cells in large numbers in culture compared to HAP stem cells not supplemented with isoproterenol. The addition of activin A, bone morphogenetic protein 4, and basic fibroblast growth factor, along with isoproternal, induced the cardiac muscle cells to form tissue sheets of beating heart muscle cells. These results demonstrate that HAP stem cells have great potential to form beating cardiac muscle cells in tissue sheets.     

谱系示踪技术揭示Tbx18+肾脏祖细胞分化为脂肪细胞

转录因子Tbx18在泌尿系发育中发挥重要作用。利用遗传谱系示踪模型，揭示了Tbx18+肾祖细胞具有向多种肾系细胞分化的潜能。但尚无文献报道其是否具有向脂肪细胞分化的潜能。本研究通过对Tbx18Cre/Rosa26LacZ双杂合小鼠泌尿系组织进行整体X-gal染色发现，肾包膜、输尿管及肾周脂肪组织能特异性表达β-gal蛋白，说明肾包膜、输尿管及肾周脂肪组织可能来源于Tbx18+祖细胞。对Tbx18Cre/Rosa26EYFP双杂合小鼠泌尿系组织进行免疫荧光染色，发现部分脂滴相关蛋白+（perilipin）脂肪细胞能表达标记蛋白EYFP，说明部分泌尿系脂肪细胞来源于Tbx18+祖细胞。本研究揭示了Tbx18+祖细胞具有分化为脂肪细胞的潜能，进一步证实了Tbx18+肾祖细胞的多分化潜能。结合本研究结果，若进一步研究肾损伤时，来源于Tbx18+祖细胞的泌尿系脂肪细胞是否进一步增多，将会为肾损伤的再生修复提供一些思路和启发。     

血管紧张素Ⅱ在胚胎干细胞向心肌细胞分化中的作用

为检测血管紧张素Ⅱ（angiotensin Ⅱ,AⅡ）对小鼠胚胎干细胞（embryonic stem cells,ESCs）向心肌细胞方向分化的作用,采用10-4 mol/L维生素C诱导小鼠R1胚胎干细胞分化为心肌细胞. Western印记检测胚胎干细胞诱导分化的心肌细胞中表达血管紧张素Ⅱ1 型受体(angiotensin Ⅱ type 1 receptor,AT1R).诱导分化期间用1 μmol/L AⅡ刺激胚胎干细胞,计数搏动拟胚体的比例;诱导分化第14 d用real-time RT-PCR 和Western 印记检测心肌标志物的表达确定其作用. 结果显示,与对照组相比,1 μmol/L AⅡ处理组可显著增加搏动拟胚体的比例,上调心肌标志物mRNA的表达. 预先用1 μmol/L洛沙坦处理1 h后可显著阻碍这种上调作用. 本实验结果表明,AⅡ通过AT1R可促进小鼠R1胚胎干细胞向心肌细胞分化.