Effect of gap junction-mediated intercellular communication on growth differentiation factor 5-induced chondrogenic differentiation in vitro

Abstract

Objective To investigate the effect of gap junctional blocker oleamide on growth differentiation factor 5 (GDF-5) induced chondrogenic differentiation.Methods hunan mesenchymal stem cells (hMSCs) were isolated and cultured in vitro,and the cells from Passage 3 were used in this study.hMSCs were randomly grouped into three according to the kinds of induction medium (0,100 μg/L GDF-5,100 μg/L GDF-5 + 2.5 μmol/L oleamide).The proliferation of hMSCs was investigated by methyl thiazol tetrazolium (MTT) assay.The cells were resuspended and the pellets were constructed by centrifugation at a density of 5 × 109/L,and then continued to be kept for two weeks.Reverse transcription-polymerase chain reaction (RT-PCR) was performed to detect the expression of mRNA of type Ⅱ collagen,comexin 43 (Cx43)and aggrecan.Western blotting was performed to detect the expression of protein of type Ⅱ collagen,Cx43and aggrecan.Toluidine blue was performed to detect extracellular matrix staining.Results GDF-5 can promote the mRNA expression of type Ⅱ collagen,Cx43 and aggrecan (1.00 ± 0.03 vs.0.40 ± 0.12 ;1.00 ±0.07 vs.0.32 ±0.02; 1.00 ±0.02 vs.0.45 ±0.01,P ＜0.01),and the relative protein expression was also increased (1.50±0.11 vs.0.53 ±0.07; 1.70 ±0.14 vs.0.52 ±0.04; 1.00 ±0.12 vs.0.50±0.06,P＜0.01).While oleamide could up-regulate the expression of mRNA of Cx43 (0.94 ±0.12 vs.0.45 ±0.01,P ＜0.01),but had no effect on type Ⅱ collagen and aggrecan mRNA expression.Oleamide could down-regulate the expression of protein of type Ⅱ collagen and aggrecan,but had no effect onCx43 protein expression(0.42 ± 0.04 vs.0.53 ±0.07; 0.38 ±0.06 vs.0.52 ±0.04,P＜0.01).Toluidine blue staining showed that GDF-5 can promote the synthesis of aggrecan.Conclusion GDF-5 modulation of chondrogenesis involves gap junction-mediated intercellular communication. Key words: Chondrogenic differentiation ; Growth differentiation factor 5 ; Oleamide ; Comexin 43