The effects of vascular endothelial growth factor (VEGF) on human orbital preadipocyte

Purpose: To investigate the presence of the Vascular Endothelial Growth Factor (VEGF) and its receptor (VEGFR) in human orbital preadipocytes, and to evaluate the effect of VEGF on human orbital preadipocyte differentiation and adipogenesis in vitro.Results: Four isoforms of VEGF (VEGF121, 155, 189, and 206), VEGFR-1, VEGF-2, and neuropilin-1 were expressed in human orbital preadipocytes. Treatment with 100 ng/ml VEGF induced higher expressions of C/EBPα and LPL than the non-treated control (p = 0.03 and p = 0.01) or treatment with 50ng/ml (p = 0.04 for both). At both concentrations VEGF enhanced the accumulation of intra-cytoplasmic lipid versus the control, and treatment with 100 ng/ml VEGF induced more lipid accumulation than treatment with 50 ng/ml VEGF (p = 0.03).Conclusions: VEGF and VEGFR were observed in human orbital preadipocytes, and exogenous VEGF enhanced adipogenesis in these cells. These results suggest that VEGF plays a role as an autocrine or paracrine growth factor during human orbital preadipocyte differentiation.     

Anti-obesity effects of seaweeds of Jeju Island on the differentiation of 3T3-L1 preadipocytes and obese mice fed a high-fat diet

The seaweeds were collected from the coast of Jeju Island, South Korea. We investigated ethanol extracts from seaweed as potential antiobesity agents by testing their effect on adipogenic differentiation in 3T3-L1 cells. Among the red algae extracts tested, the Plocamium telfairiae extract (PTE) showed the highest inhibitory effect on lipogenesis in adipocytes and, thus, was selected as a potential antiobesity agent. PTE treatment significantly decreased the expression of the adipogenic-specific proteins peroxisome proliferator-activated receptor-γ, CCAAT/enhancer-binding protein-α, sterol regulatory element-binding protein 1, and fatty acid-binding protein 4 compared with that in the untreated 3T3-L1 cells. PTE also inhibited high-fat diet (HFD)-induced obesity in male C57BL/6 mice. Oral administration of PTE significantly reduced the body weight, fatty liver, amount of white adipose tissue, and levels of triglyceride and glucose in the tested animals. Taken together, these data demonstrate that PTE can be developed as a therapeutic agent for obesity.     

The adipogenic potential of various extracellular matrices under the influence of an angiogenic growth factor combination in a mouse tissue engineering chamber

The extracellular matrix (ECM) Matrigel™ has frequently and successfully been used to generate new adipose tissue experimentally, but is unsuitable for human application. This study sought to compare the adipogenic potential of a number of alternative, biologically derived or synthetic ECMs with potential for human application, with and without growth factors and a small fat autograft. Eight groups, with six severe combined immunodeficient (SCID) mice per group, were created with bilateral chambers (silicone tubes) implanted around the epigastric vascular pedicle, with one chamber/animal containing a 5 mg fat autograft. Two animal groups were created for each of four ECMs (Matrigel™, Myogel, Cymetra® and PuraMatrix™) which filled the bilateral chambers. One group/ECM had no growth factors added to chambers whilst the other group had growth factors (GFs) (vascular endothelial growth factor-A (VEGF-A) plus fibroblast growth factor-2 (FGF-2) plus platelet-derived growth factor-BB (PDGF-BB)) added to both chambers. At 6 weeks, chamber tissue was morphometrically assessed for percent and absolute adipose tissue volume. Overall, the triple GF regime significantly increased percent¹ and absolute^# adipose tissue volume (p < 0.0005^1#) compared to chambers without triple GF treatment. The fat autograft also significantly increased percent (p < 0.0005) and absolute (p < 0.011) adipose tissue volume. Cymetra® (human collagen) constructs yielded the largest total tissue and absolute adipose tissue volume. We found that the pro-angiogenic FGF-2, VEGF-A and PDGF-BB combination in ECMs of synthetic and biological origin produced an overall significantly increased adipose tissue volume at 6 weeks and may have clinical application, particularly with Cymetra.     

CCN家族在Wnt3a抑制多潜能干细胞C3H10T1/2细胞脂肪分化中的作用

目的:探究CCN家族在Wnt3a抑制鼠胚胎间充质干细胞C3H10T1/2细胞脂肪分化过程中的作用,为干预肥胖提供新思路。方法:用激素混合物(IDM)诱导多潜能干细胞C3H10T1/2向脂肪细胞分化,观察Wnt3a对脂肪分化的抑制作用及脂肪细胞分化过程CCN家族的作用。实时定量RT-PCR分析CCN家族和PPARγ基因表达,用油红O染色观察脂肪分化程度,免疫荧光观察脂肪分化过程中细胞间基质的变化。结果:Wnt3a抑制由IDM诱导的脂肪细胞分化。分子水平上,Wnt3a显著抑制脂肪分化关键因子PPARγ的基因和蛋白表达;而IDM诱导CCN家族,尤其是CCN5基因表达的丧失,可部分被Wnt3a所逆转。结论:Wnt3a抑制C3H10T1/2的脂肪分化,至少部分归结于其对由IDM诱导的CCN家族,尤其是CCN5表达丧失的逆转。     

A Novel Semisynthetic Molecule Icaritin Stimulates Osteogenic Differentiation and Inhibits Adipogenesis of Mesenchymal Stem Cells

Background We previously reported that the constitutional flavonoid glycosides derived from herb Epimedium (EF, composed of seven flavonoid compounds with common nuclear stem) exerted beneficial effects on the bone, including promoting bone formation and inhibiting bone marrow fat deposition. Recent in vivo study showed that Icaritin was a common metabolite of these constitutional flavonoid glycosides, indicating that Icaritin is a bioactive compound. The present study was designed to investigate whether Icaritin could promote osteogenic differentiation and suppress adipogenic differentiation of marrow mesenchymal stem cells (MSCs).Methods Primary MSCs were harvested from adult mice and exposed to Icaritin to evaluate whether it could promote osteogenesis and suppress adipogenesis using the following assays: determination of alkaline phosphatase (ALP) activity and mineralization; mRNA expression of osteogenic differentiation marker Runx2; osteocalcin and bone sialoprotein (BSP) by RT-PCR; quantification of adipocyte-like cells by Oil Red O staining assay and mRNA expression for adipogenic differentiation markers peroxisome proliferator-activated receptor gamma (PPARγ); adipocyte fatty acid binding protein (aP2) and lipoprotein lipase (LPL) by RT-PCR. For the underlying mechanism, glycogen synthase kinase-3beta (GSK3β) and β-catenin were also explored by western blotting.Results Icaritin promoted osteogenic differentiation and maturation of MSCs as indicated by increased mRNA expression for Runx2, osteocalcin and BSP, and enhanced ALP activity and mineralization; Icaritin inhibited adipogenic differentiation, as indicated by decreased mRNA expression for PPARγ, LPL, aP2, and suppressed formation of adipocyte-like cells; Icaritin inactivated GSK3β and suppressed PPARγ expression when promoting osteogenesis and suppressing adipogenesis of MSCs.Conclusion This was the first study demonstrating that the novel semisynthetic molecule Icaritin could stimulate osteogenic differentiation and inhibit adipogenesis of MSCs, which was associated with the suppression of GSK3β and PPARγ.     

Sdccag3通过Wnt通路对高脂血症大鼠种植体骨结合的影响

目的 探讨Sdccag3在高脂环境中通过Wnt信号通路影响骨髓间充质干细胞(BMSCs)成脂成骨分化以及高脂血症大鼠种植体周围骨结合的能力。 方法 构建高脂血症大鼠模型以及高脂环境培养BMSCs并进行成骨诱导,慢病毒载体过表达/沉默结肠癌抗原3(Sdccag3)的表达,采用RT-PCR、Western blotting、Micro-CT以及硬组织切片HE染色、油红O染色、免疫荧光染色等方法检测高脂环境中Sdccag3对大鼠骨代谢以及BMSCs分化平衡的影响。 结果 高脂成骨诱导BMSCs后过表达Sdccag3,下调成脂分化指标脂肪酸结合蛋白4(FABP4)、过氧化物酶体增殖剂激活受体γ(PPAR-γ),并上调Wnt信号通路标志基因低密度脂蛋白受体相关蛋白 5(LRP5)、LRP6、β-catenin及Wnt5a、Wnt5b,上调成骨分化指标碱性磷酸酶(ALP)、 Runt相关的转录因子2(Runx2);在高脂血症大鼠种植体周围骨组织中,过表达Sdccag3可上调Wnt信号通路标志基因并抑制周围脂形成,沉默LRP5会下调Sdccag3、成骨分化指标,上调成脂分化指标,与沉默Sdccag3表达一致。 结论 高脂血症促进种植体周围脂肪形成并抑制Sdccag3表达;过表达Sdccag3抑制BMSCs成脂分化并降低高脂血症大鼠种植体周围的成脂,促进成骨,促进Wnt信号通路标志基因表达。     

Adipogenesis: a cross-talk between cell proliferation and cell differentiation

The transition between cell proliferation and cell differentiation taking place during adipocyte differentiation is a tightly regulated process where both cell cycle regulators and differentiating factors interact, creating a cascade of events leading to the commitment of the cells into the adipocyte phenotype. Based on in-vitro cell models of adipocyte differentiation, the different stages of adipogenesis have been established, each of them with a particular pattern of gene expression. Re-entry into the cell cycle of growth-arrested preadipocytes is known as the clonal expansion phase. Growth-arrested preadipocytes undergo several rounds of cell cycle before terminally differentiating into adipocytes, suggesting that a cross-talk might exist between the cell cycle or the cell proliferation machinery and the factors controlling cell differentiation. I will focus this review on the influence of the proliferative phase of preadipocytes in the adipocyte differentiation process.     

Inhibition of human mesenchymal stem cell-derived adipogenesis by the environmental contaminant benzo(a)pyrene

Polycyclic aromatic hydrocarbons (PAHs) such as benzo(a)pyrene (BP) are environmental contaminants exerting various toxic effects. PAHs have notably been found to inhibit adipogenesis in rodent species. To determine whether a similar process concerns human cells, we have analyzed the effects of BP towards differentiation of human cultured mesenchymal stem cells (MSC) into adipocytes, triggered by a pro-adipogenic culture medium. BP was found to markedly prevent formation of lipid vesicles, cellular lipid accumulation and up-regulation of adipogenic markers such as fatty acid binding protein-4 and glyceraldehyde-3-phosphate dehydrogenase, which represent major hallmarks of human MSC-derived adipocytes. The aryl hydrocarbon receptor (AhR), known to mediate most of the toxic effects of PAHs, was demonstrated to be present and functional in human MSC. 2,3,7,8-tetrachlorodibenzo-p-dioxin, an AhR agonist like BP, was found to inhibit lipid accumulation in human MSC cultured with adipogenic medium, in contrast to the PAH benzo(e)pyrene, known to not, or only poorly, interact with AhR. Moreover, BP inhibitory effect toward lipid accumulation in MSC exposed to adipogenic medium was fully counteracted by co-treatment with the AhR antagonist α-naphtoflavone. Taken together, these data indicate that environmental PAHs like BP can likely inhibit human adipogenesis in an AhR-dependent manner.