[Effects of conditioned media for rat bone marrow-derived mesenchymal stem cells on palmitic acid-induced insulin resistance in HepG2 cells].

Objective: To study the effect of conditioned media for rat bone marrow mesenchymal stem cells (BMSCs-CM) on palmitic acid (PA)-induced insulin resistance (IR) in HepG2 cells and its underlying molecular mechanisms.
Methods: HepG2 cells were treated with or without BMSCs-CM and L-DMEM in the presence or absence of PA.Glucose utilization in HepG2 cells were detected with PAS, glucose and glycogen measurements. Western blotting was used to assess the expression of phospho-insulin receptor substrate (p-IRS), phosphatidylinositol 3-kinase (PI3K) and p-AKT.
Results: (1) Incubation of HepG2 cells with 0.25 mmol/L PA for 24 hours significantly increased the glucose concentration and decreased the glycogen content (P<0.05) in the media. (2) Treatment with BMSCs-CM significantly ameliorated the glucose and glycogen alteration in cells pretreated with PA (P<0.05), however, no obvious effect of BMSCs-CM on the cell glucose and glycogen production. (3) BMSCs-CM treatment also increased protein expression of p-IRS, PI3K and p-AKT in PA incubated HapG2 cells (P<0.05). The effect of BMSCs-CM on PI3K and p-AKT expression could be mimicked upon addition of 740Y-P, a PI3K agonist, but abolished by LY294002, a PI3K specific inhibitor.
Conclusions: BMSCs-CM could improve the insulin sensitivity in HepG2 cells pretreated with PA through upregulation of insulin signaling component expression.