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.     

板蓝根活性组分预防肥胖作用及机制研究

目的探讨板蓝根活性组分(ACIR)的预防肥胖作用及其可能的作用机制。方法高脂饮食诱导小鼠肥胖的同时给予不同剂量ACIR,观察小鼠体质量、进食量、脂肪重量、脂肪细胞形态、肝脏重量及血脂变化,并进行小鼠负重游泳实验;体外培养诱导分化3T3-L1前脂肪细胞,观察ACIR对脂肪细胞增殖、分化和脂滴形成的影响。结果 ACIR能显著降低小鼠体质量、脂肪系数及肝脏重量,使脂肪细胞变小;改善小鼠进食量,明显延长小鼠负重游泳时间,使血清总胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白(LDL)含量降低,但高密度脂蛋白(HDL)无明显变化;抑制前脂肪细胞增殖和分化,减少脂滴形成。结论 ACIR具有预防肥胖和降血脂作用,其可能的机制是抑制前脂肪细胞增殖和分化。     

小蘖碱对甲状腺相关眼病眼眶前脂肪细胞分化的影响

目的 观察小蘖碱对体外培养的甲状腺相关眼病患者眼眶前脂肪细胞诱导分化的影响.方法 体外培养甲状腺相关眼病患者眼眶前脂肪细胞,鉴定与传代,加入小蘖碱使其浓度分别为10 mol·L-1、20 mol·L-1、40 mol·L-1、80 mol·L-1组,另设不加小蘖碱的为对照组,进行诱导分化及油红O染色,图像分析系统计算分化后脂肪细胞内脂质/核的平均积分光密度值(integrated optical density,IOD).结果 体外培养的前脂肪细胞经免疫组织化学染色鉴定为间叶来源.不同浓度小蘖碱分化后脂肪细胞内脂质/核的平均IOD值呈浓度依赖性降低,其中对照组IOD值为1.11±0.21,10 mol·L-1、20 mol·L-1、40 mol·L-1、80 mol·L-1小蘖碱组IOD值分别为0.93±0.15、0.68±0.13、0.31±0.09、0.19±0.05,与对照组相比差异有统计学意义(F=22.53,P＜0.05),组间两两比较差异均有统计学意义(均为P ＜0.05).结论 小蘖碱可以抑制眼眶前脂肪细胞的分化和细胞内脂质的形成,抑制程度呈浓度依赖性.     

Effect of Diphlorethohydroxycarmalol Isolated From Ishige okamurae on Apoptosis in 3 t3‐L1 Preadipocytes

Obesity is an important issue in the world of public health and preventive medicine. Inhibition of proliferation of preadipocytes plays an important role in proposed antiobesity mechanisms. In this study, we investigated the effect of diphlorethohydroxycarmalol (DPHC) isolated from Ishige okamurae on the apoptotic pathway. The results showed that DPHC inhibited population growth in 3 T3‐L1 preadipocytes as assessed using the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay. Flow cytometric analysis of 3 T3‐L1 preadipocytes showed that the number of early and late apoptotic cells increases in a dose‐dependent manner after exposure to DPHC, while the number of normal cells was reduced. Our findings indicate that the induction of apoptosis in 3 T3‐L1 preadipocytes by DPHC is mediated through the activation of caspase‐3, Bax, and caspase‐9, and then through the cleavage of poly(ADP‐ribose) polymerase and the down‐regulation of Bcl‐2. The data also indicated that treatment with DPHC inhibits histone deacetylase activity in 3 T3‐L1 preadipocytes. These results show that DPHC efficiently induces apoptosis in 3 T3‐L1 preadipocytes. Copyright © 2012 John Wiley & Sons, Ltd.     

Isoliquiritigenin impairs insulin signaling and adipocyte differentiation through the inhibition of protein-tyrosine phosphatase 1B oxidation in 3T3-L1 preadipocytes

Isoliquritigenin (ISL) is an abundant dietary flavonoid with a chalcone structure, which is an important constituent in Glycyrrhizae Radix (GR). ISL exhibits anti-oxidant activity, and this activity has been shown to play a beneficial role in various health conditions. However, it is unclear whether the anti-oxidant activity of ISL affects insulin signaling pathway and lipid accumulation of adipocytes. We sought to investigate the effects and molecular mechanisms of ISL on insulin-stimulated adipogenesis in 3T3-L1 cells. We investigated whether ISL attenuates insulin-induced Reactive Oxygen Species (ROS) generation, and whether ISL inhibits the lipid accumulation and the expression of adipogenic-genes during the differentiation of 3T3-L1 cells. ISL blocked the ROS generation, suppressed the lipid accumulation and the expression of adipocyte-specific proteins, which are increased in response to insulin stimulation during adipocyte differentiation of 3T3-L1 cells. We also investigated whether the anti-oxidant capacity of ISL is involved in regulating the molecular events of insulin-signaling cascade in 3T3-L1 adipocytes. ISL restores PTP1B activity by inhibiting PTP1B oxidation and IR/PI3K/AKT phosphorylation during the early stages of insulin-induced adipogenesis. Our findings show that the anti-oxidant capacity of ISL attenuated insulin IR/PI3K/AKT signaling through inhibition of PTP1B oxidation, and ultimately attenuated insulin-induced adipocyte differentiation of 3T3-L1 cells.     

芦丁促进3T3-L1前脂肪细胞棕色化及其机制

目的：观察芦丁对3T3-L1前脂肪细胞棕色化效应的影响,并探讨其机制。方法：细胞增殖与活性检测-8(CCK-8法检测不同浓度芦丁(3.125、6.25、12.5、25、50、100、200μmol·L^-1)对3T3-L1细胞活性影响,蛋白免疫印迹法(Western blot)检测不同浓度芦丁(12.5、25、50μmol·L^-1)对脂肪细胞产热相关蛋白解偶联蛋白1(UCP1)、PR结构域蛋白16(PRDM16)、过氧化物酶体增殖物激活受体γ辅助激活因子-1α(PGC-1α)表达的影响。确定芦丁最佳浓度后,油红O染色观察芦丁对脂肪细胞中脂滴生成的影响,Western blot检测线粒体生物合成标志性蛋白核呼吸因子1(NRF1)、核呼吸因子2(NRF2)和线粒体转录因子A(TFAM)的表达。结果：与空白组比较,200μmol·L^-1芦丁显著抑制3T3-L1细胞活性(P<0.01);在12.5、25、50μmol·L^-1浓度下,50μmol·L^-1芦丁显著促进产热蛋白(UCP1...     

Cells in Human Adipose Tissue Developing into Adipocytes

ABSTRACT Sedimentable cells from human adipose tissue of different origins were cultured under conditions when cell multiplication was prevented but lipid filling optimized (suspension culture). In this way an estimation was obtained of the number of in vivo determined adipose precursor cells (preadipocytes) which were not filled with lipid. Under these conditions no cells from adult, non-obese subjects developed to adipocytes. Cells developing to adipocytes constituted less than 0.02% and 1% of adipocytes in tissues from obese adults and from children, respectively. It was concluded that in vivo determined adipocyte precursor cells (preadipocytes, lipid-free fat cells) are not present in a significant number in human adipose tissue either from adults or from children as tested with the method employed, allowing detection of a large number of such cells in adipose tissue from small rats.     

褪黑素改善胰岛素抵抗3T3-L1脂肪细胞葡萄糖的摄取

目的研究褪黑素对游离脂肪酸(FFA)诱导的胰岛素抵抗3T3-L1脂肪细胞葡萄糖摄取能力的影响。方法 "鸡尾酒"法培养诱导3T3-L1成纤维细胞分化成脂肪细胞,油红O染色鉴定脂肪细胞形态;利用棕榈酸(300μmol/L)诱导脂肪细胞的胰岛素抵抗,采用液体闪烁法检测细胞葡萄糖摄取能力;检测褪黑素对FFA处理的3T3-L1脂肪细胞的葡萄糖摄取能力的影响。结果 3T3-L1细胞经诱导分化成脂肪细胞,油红O染色呈圆形,脂滴呈典型的"戒环样"形态;用FFA处理上述细胞6 h后,细胞的葡萄糖摄取能力明显降低;褪黑素可以促进FFA处理的3T3-L1脂肪细胞胰岛素介导的葡萄糖摄取。结论 FFA可以降低胰岛素诱导的体外培养的脂肪细胞葡萄糖摄取能力,可能是胰岛素抵抗的病因之一。褪黑素可以干预FFA的作用,增加细胞的葡萄糖摄取能力。     

大黄酸对大鼠前体脂肪细胞增殖与分化的影响

 目的研究大黄酸(rhein,Rh)对大鼠前体脂肪细胞增殖与分化的影响。方法采用噻唑蓝(MTT)比色法和流式细胞术测定RH对大鼠前体脂肪细胞增殖的影响。采用油红O染色提取法,检测脂肪细胞内甘油三酯积聚量的变化;采用形态学观察,检测前体脂肪细胞充脂率、充脂程度及形态变化。结果RH在5～160μmol·L^-1内,对前体脂肪细胞增殖与分化的抑制作用呈剂量和时间依赖性变化,并可在一定程度上诱发脂肪细胞凋亡。结论Rh可抑制前体脂肪细胞的增殖与分化,具有潜在的减肥降脂作用。