利用脂肪干细胞构建组织工程软骨修复兔膝关节软骨缺损

目的探讨以脂肪于细胞（ADSCs）复合脱细胞软骨基质支架构建组织工程软骨修复兔膝关节软骨缺损的效果。方法以人关节软骨脱细胞基质为支架，复合经诱导的兔ADSCs，体外分别经静态培养和生物反应器培养，构建组织工程软骨。对膝全厚关节缺损进行修复，并与单支架组、空白对照组比较，其中空白对照组12个关节，脱细胞软骨支架组16个关节，静态培养细胞支架组24个关节，生物反应器培养细胞支架组8个关节。分别于术后3、6个月对修复关节进行大体、组织学及免疫组化观察。结果实际完成观察的关节数为44个，其中空白对照组9个，脱细胞软骨支架组11个，静态培养细胞支架组18个，生物反应器培养细胞支架组6个。空白对照组全为纤维组织或纤维软骨样修复；单支架组5个关节为未成熟透明软骨，无成熟透明软骨形成；静态培养细胞支架组83．3％为透明软骨，其中3个关节为成熟透明软骨，12个关节为未成熟透明软骨；生物反应器培养细胞支架组100％为透明软骨，其中2个为成熟透明软骨，4个为未成熟透明软骨。Wakitani评分各组差异有统计学意义（P〈0．05）。结论ADSCs复合脱细胞软骨基质支架能良好地修复兔膝关节全厚软骨缺损，应用生物反应器技术有助于构建组织工程软骨，促进软骨缺损的修复。     

RNA干扰对脂联素在3T3-L1脂肪细胞中表达的影响

设计合成3对ACRP30编码基因的反向重复序列，分别定向克隆至载体psilencer1．0的U6启动子下游，构建了相应的shRNAs表达质粒，并证实了这些重组质粒对成熟脂肪细胞中脂联素蛋白的表达有显著的抑制作用。     

胰岛素上调3T3-L1细胞apelin基因表达的初步观察

Northern印迹法证实apelin在分离的小鼠脂肪细胞上有表达，其表达量随3T3-L1细胞分化而渐增。胰岛素上调3T3-L1脂肪细胞apelin的表达，提示脂肪细胞apelin的表达可能与肥胖、胰岛素抵抗、高血压相关。     

胰升血糖素样肽1对3T3-L1前脂肪细胞增殖及分化的影响

目的探讨胰升血糖素样肽1（GLP-1）对3T3-L1前脂肪细胞增殖及分化的影响。方法在3T3-L1前脂肪细胞增殖和分化的不同阶段添加不同浓度梯度的GLP-1（7—36）,使用XTT比色法测定细胞增殖情况,油红O脂肪染色、异丙醇萃取法评价细胞分化情况,RT-PCR法测定不同分化阶段PPAR-ymRNA表达水平。结果高浓度GLP-1（10^-9～10^-7mool／L）能够减弱3T3-L1前脂肪细胞的增殖能力;GLP-1在10^-11～10^-8mmoL／浓度梯度均存在抑制3T3-L1前脂肪细胞向脂肪细胞分化的作用,但对分化过程中PPARymRNA的表达水平均未见显著影响。结论本研究发现GLP-1能够抑制3T3-L1前脂肪细胞增殖及分化,提示脂肪细胞可能也是GLP-1减轻体重作用的潜在靶点。     

性激素对脂肪细胞瘦素和脂联素分泌的影响

目的 观察性激素对前脂肪细胞增殖与分化及脂肪细胞瘦素脂联素分泌的影响.方法 原代培养人大网膜前脂肪细胞,观察其增殖、分化过程.性激素作用前脂肪细胞增殖和分化过程,检测瘦素、脂联素分泌及mRNA水平.结果 成功地培养出人大网膜前脂肪细胞.雌二醇促进前脂肪细胞增殖(0.823±0.059对0.276±0.032,P＜0.05)、抑制分化(P＜0.05);睾酮对前脂肪细胞增殖无明显作用,但抑制分化(P＜0.05).前脂肪细胞增殖及分化期均分泌瘦素.雌二醇促进瘦素分泌,而睾酮抑制(均P＜0.05).脂联素仅在分化期分泌,且性激素抑制其分泌.雌二醇促进瘦素mRNA表达但抑制脂联素mRNA表达;睾酮抑制瘦素、脂联素mRNA表达(均P＜0.05).结论 雌二醇促进脂肪细胞瘦素分泌及mRNA表达,抑制脂联素分泌及mRNA表达;睾酮抑制二者分泌及mRNA表达.     

The release of the adipocytokine visfatin is regulated by glucose and insulin

Aims/hypothesis The novel insulin-mimetic adipocytokine visfatin has been linked to the metabolic syndrome, but its regulation has not been characterised to date. Since insulin-mimetic actions of visfatin may be part of the feedback regulation of glucose homeostasis, we hypothesised that visfatin concentrations are influenced by glucose or insulin blood levels in humans.Subjects, materials and methods In this randomised, double-blind, placebo-controlled crossover study, nine healthy male subjects (age 26±6 years) attended three different study days. On each day, systemic glucose concentrations of 5.0, 8.3 and 11.1 mmol/l were attained by stepwise increases in i.v. infusions of glucose, representing fasting and postprandial conditions. Visfatin plasma concentrations were studied during concomitant exogenous hyperinsulinaemia, inhibition of endogenous insulin production by somatostatin infusion, and placebo time control. Additionally, human adipocytes were cultured to study visfatin release and mRNA expression in vitro.Results Glucose concentrations of 8.3 and 11.1 mmol/l increased circulating visfatin from baseline concentrations of 0.5±0.0 ng/ml to 0.9±0.1 and 2.1±0.3 ng/ml, respectively (p<0.01). Glucose-induced elevation of visfatin was prevented by co-infusion of insulin or somatostatin (p<0.05). Cultured subcutaneous and visceral adipocytes released an equivalent amount of visfatin upon glucose-concentration- and time-dependent stimulation. Visfatin secretion involved the phosphatidylinositol 3-kinase (PI3-kinase) and protein kinase B (AKT) pathways. The mRNA expression pattern of visfatin was consistent with this altered protein release.Conclusions/interpretation Circulating visfatin concentrations are increased by hyperglycaemia. This effect is suppressed by exogenous hyperinsulinaemia or somatostatin infusion. Glucose signalling for visfatin release in adipocytes involves the PI3-kinase/AKT pathway.     

胆固醇过负荷对脂肪细胞分泌内脂素的影响及其机制

3T3-L1细胞促分化成熟后,分别以酯酰辅酶A胆固醇酯酰转移酶(ACAT)抑制剂(2μg/ml)和不同浓度(0、25、50、75和100 μg/ml)的氧化型低密度脂蛋白(ox-LDL)干预48 h,ACAT抑制剂(2μg/ml)和ox-LDL( 50 μg/ml)干预0、6、18、36和48 h,ACAT抑制剂(2μg/ml)、ox-LDL( 50 μg/ml)和不同浓度(0、100、200和400 μmol/L)的牛磺酸熊去氧胆酸(TUDCA)干预48 h.用ELISA法检测细胞上清内脂素的水平,Western印迹法检测脂肪细胞总蛋白GRP78和CHOP表达.ACAT抑制剂和不同浓度的ox-LDL干预脂肪细胞48 h后,随着ox-LDL浓度的增加,脂肪细胞内胆固醇浓度、GRP78和CHOP蛋白表达及内脂素水平显著升高,实验组与空白对照组比较,差异均具有统计学意义(均P＜0.05);ACAT抑制剂和ox-LDL干预后,随干预时间的延长,脂肪细胞GRP78、CHOP蛋白表达及内脂素水平均显著升高,实验组与空白对照组比较,差异均有统计学意义(均P＜0.05);ACAT抑制剂、ox-LDL和不同浓度TUDCA干预48 h后,脂肪细胞GRP78及CHOP蛋白表达水平及内脂素水平逐渐降低,实验组(200和400 μmol/L)与空白对照组比较,差异均有统计学意义(均P＜0.05).脂肪细胞胆固醇负荷增加可促进脂肪细胞分泌内脂素,其机制可能与脂肪细胞的内质网应激增强有关.     

The metabolic syndrome is related to b 3-adrenoceptor sensitivity in visceral adipose tissue

Summary The metabolic syndrome is a well-known risk for the development of cardiovascular disease. In the present study the possible importance of an altered visceral adipocyte β -adrenoceptor function in this syndrome was investigated. In 65 subjects of both sexes undergoing elective surgery for non-malignant disorders, the metabolic syndrome phenotype and the lipolytic sensitivity for various β -adrenoceptor subtype agonists in omental adipocytes were determined. The study group represented a wide range of abdominal adipose tissue distribution (waist-to-hip ratios 0.76–1.13), but was otherwise apparently healthy. The subjects were divided into three subgroups according to their waist-to-hip (WHR) ratios: 1) WHR < 0.92; 2) WHR 0.92–1.04; 3) WHR > 1.04. The subgroups demonstrated significant differences regarding body mass index, sagittal diameter, systolic and diastolic blood pressures, plasma concentrations of glucose, insulin, triglycerides and HDL-cholesterol (p = 0.005–0.0001). Furthermore, in omental adipocytes β ₃-adrenoceptor sensitivity, but not β ₁- and β ₂-adrenoceptor sensitivities, differed significantly between the WHR subgroups (p = 0.0001). β ₃-adrenoceptor sensitivity was also related to the other components of the metabolic syndrome, although a strong covariation between WHR and β ₃-adrenoceptor sensitivity vs blood pressure and the metabolic parameters was found. The present data provide evidence of a relationship between upper-body obesity and its associated metabolic complications and also, an increased visceral fat β ₃-adrenoceptor sensitivity. We suggest that the latter finding results in an augmented release of non-esterified fatty acids from the visceral fat depot to the portal venous system. This may in turn contribute to the development of the metabolic syndrome. [Diabetologia (1996) 39: 838–844] Received: 15 September 1995 and in final revised form: 24 January 1996     

Metabolic adaptations in the adipose tissue that underlie the body fat mass gain in middle-aged rats

Little is known about adipocyte metabolism during aging process and whether this can influence body fat redistribution and systemic metabolism. To better understand this phenomenon, two animal groups were studied: young—14 weeks old—and middle-aged—16 months old. Periepididymal (PE) and subcutaneous (SC) adipocytes were isolated and tested for their capacities to perform lipolysis and to incorporate D-[U-¹⁴C]-glucose, D-[U-¹⁴C]-lactate, and [9,10(n)-³H]-oleic acid into lipids. Additionally, the morphometric characteristics of the adipose tissues, glucose tolerance tests, and biochemical determinations (fasting glucose, triglycerides, insulin) in blood were performed. The middle-aged rats showed adipocyte (PE and SC) hypertrophy and glucose intolerance, although there were no significant changes in fasting glycemia and insulin. Furthermore, PE tissue revealed elevated rates (+50 %) of lipolysis during beta-adrenergic-stimulation. There was also an increase (+62 %) in the baseline rate of glucose incorporation into lipids in the PE adipocytes, while these PE cells were almost unresponsive to insulin stimulation and less responsive (a 34 % decrease) in the SC tissue. Also, the capacity of oleic acid esterification was elevated in baseline state and with insulin stimulus in the PE tissue (+90 and 82 %, respectively). Likewise, spontaneous incorporation of lactate into lipids in the PE and SC tissues was higher (+100 and 11 %, respectively) in middle-aged rats. We concluded that adipocyte metabolism of middle-aged animals seems to strongly favor cellular hypertrophy and increased adipose mass, particularly the intra-abdominal PE fat pad. In discussion, we have interpreted all these results as a metabolic adaptations to avoid the spreading of fat that can reach tissues beyond adipose protecting them against ectopic fat accumulation. However, these adaptations may have the potential to lead to future metabolic dysfunctions seen in the senescence.     

WNT2B对人骨髓间充质干细胞成脂肪细胞分化的影响

目的观察WNT2B对人骨髓间充质干细胞(hMSCs)向脂肪细胞分化的影响。方法采用慢病毒载体在hMSCs中过表达WNT2B基因(实验组),以空慢病毒载体作为对照(对照组),并将hMSCs进行脂肪细胞诱导分化7 d,以实时定量聚合酶链反应(qPCR)检测脂肪细胞标志基因过氧化物酶增殖物激活受体γ2(PPARγ2)、脂蛋白脂酶(LPL)和降脂素(Adipsin)的表达,在光镜下计数油红O染色阳性细胞的数目,并对油红O染色强度进行定量检测。计量数据组间比较采用t检验或者Mann-Whitney检验。结果在hMSCs成脂肪细胞诱导分化过程中,WNT2B的蛋白表达水平在分化早期即发生改变,实验组hMSCs的PPARγ2(3.85±0.01比0.70±0.10,t=54.289,P<0.01)、LPL(17.78±1.78比1.29±1.30,t=12.958,P<0.01)、Adipsin基因表达强度(0.88±0.11比0.38±0.05,t=7.167,P<0.01)显著低于对照组,实验组hMSCs单位面积形成脂肪细胞的数量显著低于对照组[(30.50±2.07)个比(10.33±1.63)个,t=50.230,P<0.01],油红染色定量分析显示实验组吸光度值显著低于对照组(0.77±0.02比0.49±0.02,t=10.397,P<0.01),差异均有统计学意义。结论过表达WNT2B可以抑制体外hMSCs向脂肪细胞的分化。