积雪草酸改善小鼠脂肪细胞胰岛素抵抗的机制研究

 目的： 观察番石榴叶三萜化合物积雪草酸对小鼠3T3-L1前脂肪细胞增殖、分化以及胰岛素抵抗脂肪细胞糖脂代谢的影响并探讨其作用机制。方法：MTT法检测药物对3T3-L1前脂肪细胞增殖的影响;油红O染色法观察药物对其分化的影响。地塞米松诱导建立脂肪细胞胰岛素抵抗模型,药物干预后采用葡萄糖氧化酶法检测培养液中葡萄糖消耗量;比色法检测游离脂肪酸浓度;ELISA法检测脂联素水平;Western blotting法检测过氧化物酶体增殖物激活受体γ（PPARγ）和蛋白酪氨酸磷酸酶1B(PTP1B)蛋白表达的变化。结果：与溶媒对照组相比,积雪草酸在10~100 μmol/L时能显著促进3T3-L1前脂肪细胞增殖,但明显抑制其分化（P<0.05或P<0.01）;在30和100 μmol/L时,无论是基础状态还是胰岛素刺激状态,均能显著增加胰岛素抵抗脂肪细胞葡萄糖的消耗,减少游离脂肪酸的产生（P<0.05）;其对胰岛素抵抗脂肪细胞的脂联素分泌和PPARγ蛋白表达无明显影响（P>0.05）,但能显著下调PTP1B蛋白的表达（P<0.05或P<0.01）。结论：积雪草酸能显著改善脂肪细胞胰岛素抵抗,增加胰岛素抵抗脂肪细胞葡萄糖的消耗和减少游离脂肪酸的产生,其机制可能是其下调胰岛素信号转导的负性调节因子PTP1B的表达,增强胰岛素信号转导,从而改善胰岛素抵抗。     

DIFFERENTIATION OF PREADIPOCYTES IS REGULATED BY INSULIN-LIKE GROWTH FACTOR-1

Preadipocytes converted to adipocytes when insulin-like growth factor-1 or insulin was added to a medium depleted of those compounds. A variety of mRNA molecules characteristic of the adipocytes were induced.     

Engineering of Adipose Tissue by Injection of Human Preadipocytes in Fibrin

Background Despite efforts of plastic surgeons in recent years to discover new alternatives, the techniques currently used for restoration of soft tissue defects still have disadvantages. The gold standard for soft tissue reconstruction remains autologous pedicled/free tissue transfer. This technique often results in high rates of operative morbidity and donor site deformity. Results obtained by autologous fat tissue transfer usually are disappointing because of a high graft resorption rate with unpredictable outcomes. Different tissue engineering approaches have been used in the past to generate adipose tissue. However, long-term results in terms of volume persistence have been disappointing. Methods In this study, different concentrations of undifferentiated human preadipocytes in fibrin were injected into athymic nude mice (n = 8). Mice that had fibrin injection without cells served as control subjects (n = 8). The specimens were explanted after 1, 2, 6, and 9 months, with subsequent qualitative and quantitative analysis of adipose tissue formation by histologic and image analysis. Results Within the first 4 weeks after initial volume reduction of the implants, the volume and shape of the implants with preadipocytes remained stable. The implants without cells were completely resorbed within 3 weeks. Histologic analysis demonstrated generation of stable adipose tissue with no signs of an inflammatory response or evidence of tissue necrosis in the implants containing preadipocytes. The best results were obtained after implantation of 30 million preadipocytes. Adipose tissue formation was not observed in the control group. Conclusions The findings demonstrate that long-term stable adipose tissue can be engineered in vivo by simple injection of human preadipocytes using fibrin as a carrier material. After further investigation, this approach may represent an alternative to the techniques currently used for soft tissue restoration. Presented at the 36th Conference of the Association of German Plastic Surgeons (DGPRA) in Munich, Germany, September 2005, and at the 8th Conference of the Association of French Aesthetic and Plastic Surgeons (SOFCEP) in Paris, France, June 2005     

六味地黄丸入血成分莫诺苷对大鼠前脂肪细胞增殖与分化的影响

目的:测定大鼠口服六味地黄丸后血清中莫诺苷浓度,并探讨莫诺苷对大鼠前脂肪细胞增殖与分化的影响。方法:反相高效液相色谱法检测大鼠口服六味地黄丸后血清中莫诺苷浓度;原代培养大鼠前脂肪细胞;以四甲基偶氮唑盐(MTT)方法检测莫诺苷对大鼠前脂肪细胞增殖的影响;以油红O染色方法检测其对大鼠前脂肪细胞分化过程中的细胞内脂肪积聚的影响。结果:莫诺苷与血清中其它成分较好分离。在250～2000ng范围内线性关系良好(r=0.9991),平均回收率为95.27%,莫诺苷在大鼠血中的平均血药浓度为(16.92±3.63)μg/mL;8.5～68.0μg/mL的莫诺苷促进大鼠前脂肪细胞的增殖,抑制其分化过程中的脂肪积聚。结论:莫诺苷可能为六味地黄丸的体内直接作用物质之一;有效成分分离测定与药效学研究相结合的方法将有助于阐明六味地黄丸的有效成分及作用机理。     

hsa-miR-17-92 cluster及其同源体靶基因的生物信息学分析

目的 对hsa-miR-17-92 cluster及其同源体进行系统的生物信息学分析,预测其可能参与的生物学过程,为深入研究其在脂肪细胞分化、肥胖发生等过程中的功能与机制奠定基础.方法 1.应用PubMed、Google等信息搜索工具查找hsa-miR-17-92 cluster及其同源体的所有研究,综述已有研究进展;2.应用miRBase获取hsa-miR-17-92 cluster及其同源体的各成员序列,并分析其序列特征及保守性;3.应用美国国家生物技术信息中心(NCBI) blast、NCBI mapviewer、基因组生物信息学(UCSC) Browser工具分析hsa-miR-17-92 cluster及其同源体所在基因组的序列特征;4.应用TargetScan5.1,PicTar及miRanda预测hsa-miR-17-92 cluster及其同源体靶基因,取三者预测结果的交集,进一步进行功能注释和Pathway富集分析.结果 1.现有研究提示hsa-miR-17-92 cluster及其同源体在脂肪细胞分化、肿瘤疾病、心脏及肺发育、免疫系统与血管形成等生物学过程中有重要作用;2.hsa-miR-17-92 cluster及其同源体进化上高度保守,根据种子序列同源性可分为4类,且在多物种间非常保守;3.hsa-miR-17-92 cluster及其同源体预测靶基因的功能与细胞周期、细胞黏附、Wnt、TGF-β信号、p53、丝裂原活化蛋白激酶等信号通路有较大的相关性,可能参与了前列腺癌、胰腺癌、结肠癌等多种疾病通路.结论 通过对hsa-miR-17-92 cluster及其同源体系统的生物信息学分析,初步阐明了hsa-miR-17-92 cluster及其同源体的基本生物学特征,并为hsa-miR-17-92 cluster后续研究提供了功能与机制的线索.     

Integrin α4 impacts on differential adhesion of preadipocytes and stem cells on synthetic polymers

Stem cells represent an ideal cell source for tissue engineering and regenerative medicine, because they can be readily isolated, expanded, differentiated and transplanted. For stem cell‐based therapies, biomaterials are required to allow for a spatial distribution of the stem cells within a defined area in the body. In our recent studies, we analysed the interaction of a large panel of stem cell types with an array of biomaterials and demonstrated that a rational prediction of stem cell behaviour on a specific biomaterial is so far not possible. Interestingly, even ontogenetically related stem cell types, such as mesenchymal stem cells (MSCs), preadipocytes and dental pulp stem cells (DPSCs), exhibit distinct adhesion properties on the very same biomaterial surface. Therefore, we investigated integrin and extracellular matrix (ECM) protein expression of stem cells to relate gene expression to adhesion behaviour. MSCs, preadipocytes and DPSCs were cultured on selected synthetic polymers, such as Texin, a thermoplastic polyurethane, poly(dimethyl siloxane) (PDMS), poly‐d,l ‐lactic acid (PDLLA) and l ‐lactic acid‐trimehylene carbonate (Resomer® LT706). Integrins and ECM proteins were analysed by RT–PCR, real‐time PCR and immunohistochemistry. Analysis of several adhesion molecules yielded that only one molecule, integrin α4, might play a significant role in differential adhesion on polymers for preadipocytes compared to DPSCs and MSCs. Thus, our studies on the molecular interactions of stem cells and polymers are expected to lead to a more profound understanding of the stem cell–biomaterial interactions to eventually allow for a rational biomaterial design. Copyright © 2012 John Wiley & Sons, Ltd.