Inherent Abnormalities of Fat Cells from Massively Obese Individuals

In vitro investigations into adipose cell dynamics have revealed intrinsic characteristics of massively obese individuals' cells that could contribute to a relatively intractable expanded fat mass. Morbidly corpulent peoples' preadipocytes replicate to a greater degree than those from lean individuals. Coupled with exaggerated differentiation this enhanced growth would result in a greater number of fat cells which would increase adipose tissue mass. The relative resistance to de-differentiation that adipocytes from the massively obese demonstrate would contribute to stability of an increased number of adipocytes further exacerbating the problem. The increased message of an energy sensing protein, the obese gene product, suggests that the morbidly obese are insensitive to its action. Together these attributes provide a strong argument for a significant genetic role in the pathogenesis of obesity.     

Androgen receptors in cultured rat adipose precursor cells during proliferation and differentiation: regional specificities and regulation by testosterone

Different studies suggest that sex hormones affect adipose tissue metabolism and deposition. To investigate the possibility that androgens may play a role in adipose tissue development, we have studied androgen receptors (AR) in rat adipose precursor cells from two different anatomical fat deposits, one deep intraabdominal (epididymal) and one subcutaneous (inguinal) during the proliferation and differentiation processes. AR were quantified by [³H]R1881 specific binding in whole cells and the nuclear fraction and were localized by immunocytofluorimetry in both the cytosol and the nucleus. During the proliferative phase, total AR level decreased from D3 to D6. At confluence (D5), AR were higher in epididymal (64±4 fmol/mg protein) than in subcutaneous (33±3 fmoles/mg proteins) preadipocytes and were up-regulated by testosterone but not by 5α-dihydrotestosterone or by 17β-estradiol. At differentiation (D10-11), nuclear AR decreased by 50% in both precursor fat cell populations when compared to the confluent state (D5) and AR were no more up-regulated but rather down-regulated by testosterone. Because AR are present in preadipocytes and are differently regulated by testosterone depending on the stage of proliferation and differentiation, this study suggests that testosterone may play a role in the control of the adipogenic process.     

大黄素对大鼠前体脂肪细胞增殖与分化的影响

目的：研究大黄素(emodin,EMO)对大鼠前体脂肪细胞增殖与分化的影响。方法：分离培养大鼠前体脂肪细胞,按照EMO添加剂量不同,把培养板中接种细胞的培养孔随机分为0,5,10,20,40,80,160 μmol·L^-1 处理组；采用MTT比色法和流式细胞术测定EMO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,检测前体脂肪细胞分化的形态学变化。结果：20～160 μmol·L^-1 的EMO对大鼠前体脂肪细胞的增殖与分化呈剂量和时间依赖性地抑制作用,并可在一定程度上诱发前体脂肪细胞凋亡。结论：EMO具有潜在的减肥降脂作用。     

六味地黄丸对大鼠前脂肪细胞增殖与分化的影响

目的探讨六味地黄丸对大鼠前脂肪细胞增殖与分化的影响。方法原代培养大鼠前脂肪细胞,用四甲基偶氮唑盐(MTT)方法检测六味地黄丸含药血清对前脂肪细胞的增殖情况,以酶组织化学法检测其对前脂肪细胞分化过程中的磷酸甘油脱氢酶(GPDH)的影响,油红O染色方法测定其对细胞内脂肪积聚的影响。结果10%以内六味地黄丸含药血清对大鼠前脂肪细胞的增殖有促进作用,对分化过程中的GPDH升高有抑制作用,而对于分化过程中的脂肪积聚则有促进分解的作用。结论六味地黄丸能促进大鼠前脂肪细胞的增殖,抑制大鼠前脂肪细胞的分化。     

Effects of pioglitazone on proliferation and differentiation of human preadipocytes

Objective: To explore the effects of thiazolidinediones (TZDs) pioglitazone on proliferation and differentiation of human preadipocytes. Methods :Omental adipose tissue biopsies were obtained from 15 patients who were undergoing elective open-abdominal surgery. The primary culture and differentiated induction of human preadipocytes were performed, and the human preadipo-cytes were treated with pioglitazone at different concentrations at proper moments. Dynamic morphological changes of the human preadipocytes were observed, and their proliferation and differentiation were assessed with Colorimetric MTT Assay and Oil Red O Staining. Results:After 24 hours and 72 hours with pioglitazone, 0.1 μmol/L (μmol/ml) pioglitazone increased the MTT values of the human preadipocytes by 25.3% and 34.8% ,respectively(P ＜ 0.05), while 1 μ mol/L pioglitazone by 27.4% and 26.6%(P＜ 0.05), compared with the control group without pioglitazone. The human preadipocytes with pioglitazone cumulated more adipose in the endochylema than those without pioglitazone obviously. 0.1 μmol/L pioglitazone increased the differentiation degree of the human preadipocytes differentiated for 8-10 days by 44.81% and 1 μmol/L pioglitazone by 53.76%(P ＜ 0.05). Conclusion:Thiazolidinediones pioglitazone may significantly promote the proliferation and differentiation of the human omental preadipocytes.     

Characterisation of angiogenetic growth factor production in adipose tissue-derived mesenchymal cells

Abstract

Optimal vascularisation of the graft site is significant for improving the outcome of fat grafting. Adipose tissue, specifically the stromal vascular fraction (SVF), is known to regulate its own vascular network. In order to assess the production of angiogenetic growth factors, this study investigated the content of insulin growth factor (IGF), vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), platelet-derived growth factor (PDGF), leptin, and metallothioneine-9 (MMP-9) in the SVF after incubation in differentiation or proliferation media. The SVF was isolated from human subcutaneous adipose tissue. Cells were either cultured in proliferation medium (PM) or in differentiation medium (DM). The samples were analysed for the respective factors using ELISA after 3 and 6 days. The GF levels showed a distinctive characteristic over time depending on the culture medium. IGF, PDGF, and MMP-9 levels decreased with PM and increased with DM. VEGF levels were increased in both media. Leptin showed a decrease in both media. The differentiation medium was associated with high inter-individual distribution in growth factor production except for PDGF and Leptin. In conclusion, incubation with differentiation medium produces a more reliable increase of selected growth factors than incubation with proliferation medium. Enrichment of fat grafts with growth factor-activated autologous SVF samples could help to enable better ingrowth of the transplanted tissue and a more stable outcome. The scattering of the results could explain the inter-individual differences regarding the outcome.     

染料木黄酮对3T3-L1前脂肪细胞分化的作用及其机制研究

目的观察染料木黄酮(genistein,GEN)对3T3-L1前脂肪细胞分化的影响,探讨GEN抑制3T3-L1细胞分化的作用及分子机制。方法用含1-甲基-3-异丁基黄嘌呤、地塞米松和胰岛素的培养液(MDI)诱导3T3-L1前脂肪细胞分化,同时用GEN或p38抑制剂SB203580干预。作用6d后,用油红染色实验观察脂肪形成情况;检测细胞培养液中非酯化脂肪酸(NEFA)、甘油三酯(TG)的含量;用Western blotting技术检测细胞中脂肪酸合酶(FAS)的蛋白表达。用GEN预处理30min后,用胰岛素刺激3T3-L1细胞,检测磷酸化p38MAPK(p-p38)的蛋白表达。结果GEN可以有效抑制3T3-L1细胞的脂肪形成,降低培养液中NEFA、TG的含量。胰岛素刺激后,3T3-L1细胞中p-p38的表达迅速增强,并在5min时达到高峰,GEN可以有效降低p-p38的表达。GEN、SB203580均能降低FAS的蛋白表达。结论染料木黄酮能有效抑制3T3-L1前脂肪细胞的脂肪分化,其机制是通过p38途径对FAS的抑制发挥作用。     

Effects of 4-nonylphenol on adipogenesis in 3T3-L1 preadipocytes and C3H/10T1/2 mesenchymal stem cells

Obesogens are a subset of endocrine disruptor chemicals (EDCs) that cause obesity. The typical EDC 4-nonylphenol (4-NP) has been identified as an obesogen. However, the in vitro effects of 4-NP on adipogenesis remain unclear. In this study, 3T3-L1 preadipocytes and C3H/10T1/2 mesenchymal stem cells (MSCs) were used to investigate the influence of 4-NP on adipogenesis. The differentiation protocols for 3T3-L1 preadipocytes and C3H/10T1/2 MSCs took 8 and 12 days, respectively, beginning at Day 0. In differentiated 3T3-L1 preadipocytes, 20 μM 4-NP decreased cell viability on Days 4 and 8. Exposure to 4-NP inhibited triglyceride (TG) accumulation and adipogenic marker expression on Days 0–8, but the inhibitory effects were weaker on Days 2–8. The protein expression of pSTAT3 or STAT3 decreased on Days 0–8 and 2–8. Conversely, 4-NP promoted TG accumulation and the adipogenic marker expression in C3H/10T1/2 adipocytes. The opposing effects were attributed to physiological differences between the two cell lines. The 3T3-L1 preadipocytes are dependent on mitotic clonal expansion (MCE) to drive differentiation, while C3H/10T1/2MSCs and human preadipocytes are not. Additionally, 4-NP downregulated β-catenin expression in C3H/10T1/2 adipocytes. Accordingly, we hypothesized that 4-NP promotes adipogenesis. The role of the canonical Wnt pathway in the promotion of adipogenesis by 4-NP requires further validation. This study provides new insights into the mechanisms and appropriate risk management of 4-NP.     

Autologous in vivo adipose tissue engineering in hyaluronan-based gels--a pilot study

BACKGROUND: There is a major clinical need for strategies for adequately reconstructing the soft tissue defects found after deep burns, tumor resection, or trauma. A promising solution is adipose tissue engineering with preadipocytes, stem-cell derived precursors of the adipose tissue, implanted within biomaterials. This pilot study evaluated hyaluronan gels mixed with autologous undifferentiated preadipocytes in a pig model for their potency to generate new fat. MATERIALS AND METHODS: Preadipocytes were isolated from intra-abdominal pig fat by collagenase digestion, plated on fibronectin-coated culture dishes in Dulbecco's modified Eagle medium/Ham's F12 (Biochrom, Berlin, Germany) combined with 10% pig serum, expanded, and mixed with hyaluronan gel. Two types of gels with varying degrees of amidation of the carboxyl groups were tested (HYADD3, HYADD4). Cell-loaded gels and unseeded controls were injected subcutaneously into the ears of three pigs, explanted at 6 wk, and analyzed histologically. RESULTS: Both cell-loaded specimens were detected macroscopically. They demonstrated a slight volume effect with limited stability after 6 wk. Unloaded HYADD3 and HYADD4 controls could not be identified at the time of explantation. Histology of HYADD3 revealed islets of mature adipocytes and vessels embedded in fat tissue surrounded by gel. In contrast, no fat formation was found in HYADD4 gels when implanted in the ear. CONCLUSIONS: Histological findings demonstrate that HYADD3 is a promising gel for generating adipose tissue. Even though HYADD3 might be a potential material for the reconstruction of small tissue defects, the question remains as to whether the adipose tissue within the gel is attributable to preadipocyte maturation or ingrowth from neighboring tissue.     

Effects of aging on ribosomal protein L7 messenger RNA levels in cultured rat preadipocytes

Ribosomal protein L7 mRNA is a cell cycle-independent message whose levels are lower in late passage “senescent” fibroblasts than early passage cultures. To determine whether decreases in L7 mRNA levels also occur during aging in tissues in vivo and whether reduced L7 mRNA is caused by terminal differentiation, we measured L7 and adipsin (a differentiation-dependent serine protease) mRNA levels in undifferentiated and differentiated preadipocytes and glyceraldehyde-3-phosphate dehydrogenase mRNA in differentiated preadipocytes cultured from perirenal fat depots of 3-, 17-, and 24-month-old male rats. L7 mRNA levels decreased with increasing age and were not affected by differentiation. In the same cultures, adipsin mRNA levels did not increase with age but did increase with differentiation, confirming that the preadipocytes exposed to enriched medium had, in fact, differentiated. Glyceraldehyde-3-phosphate dehydrogenase mRNA levels did not change with age indicating that the decrease in L7 mRNA was not a result of a general decrease in mRNA with age. These observations are consistent with the hypotheses that decreasing L7 mRNA levels are associated with aging and that late passage fibroblasts have features in common with senescence. The observations are not consistent with the hypothesis that senescent changes in cellular function are caused by terminal differentiation.