Remnant-like Particles Induce Adipogenic Differentiation Of Adipose Mesenchymal Stem Cells Through Activating Peroxisome Proliferators Activated Receptor γ

BackgroundObesity usually coexists with hypertriglyceridemia which represents the increased triglyceride-rich lipoproteins and their metabolic products, remnant-like particles (RLPs), in circulation. It has been demonstrated that RLPs can induce rat adipose-derived mesenchymal stem cells (ADSCs) to differentiate into mature adipocytes.Peroxisome proliferators activated receptory (PPARγ) is a central regulator of adipocyte differentiation and can up-regulate the expressions of adipokines,such as leptin, adiponectin (APN) and so on. It is conjectured that RLPs could induce human ADSCs to differentiate into adipocytes through activating PPARy.ObjectiveTo explore the effects of RLPs on the adipogenic differentiation of human ADSCs and on the mRNA expressions of PPARy and APN.MethodsCollagenase type I was used to isolate ADSCs from human adipose tissue.Then cells were cultured and passaged in culture medium which contained DMEM/F12 supplemented with 10% FBS.ADSCs were identified by flow cytometry analysis.After stimulation by standard inducer containing 3-isobutyl-l-methylxanthine,dexamethasone, and 10μg/ml insulin, the morphological changes of ADSCs were observed under optical microscope and lipid droplets within cells were identified by Oil red O staining. Taking ADSCs stimulated by 10μg/mL insulin alone as the control group,ADSCs were divided into four groups stimulated by 10μg/mL insulin and different concentration of RLPs (50, 100,150,200μg/mL).After 12 days,the lipid droplets were identified by Oil red O staining and the expressions of PPARy and APN were measured by RT-PCR.ResultsA Spindle ADSCs grew as fibroblasts do and stably proliferated in DMEM/F12 culture medium. The expression profile of cultured ADSCs included CD31(8.71±0.57)%,CD34(4.39±0.94)%, KDR(1.89±0.05)%,and CD105 (53.43±2.24)%.After stimulation by standard inducer, spindle ADSCs became bigger and rounder in shape, and lipid droplets emerged within cells.After stimulation by RLPs for 12 days,a small amount of lipid droplets was found in the control group or 50μg/mL RLPs stimulated ADSCs by Oil red O staining. Lipid droplets increased gradually with the elevation of RLPs concentration from 100 to 200μg/mL in the other three groups, among these was 200μg/mL RLPs stimulated ADSCs that showed the largest amount of lipid droplets.The different amounts of PPARy and APN mRNA expressions were detected in ADSCs stimulated by different concentrations of RLPs.ConclusionsRLPs induce human ADSCs to differentiate into adipocytes through activating PPARγ,accompanying with the up-regulation of APN expression.