FGF‐2 Regulates Valve Interstitial Cell Repair Through TGF‐b/Smad Signaling

Abstract

BackgroundTransforming growth factor‐β (TGF‐β) and fibroblast growth factor‐2 (FGF‐2) both promote valve interstitial cell (VIC) repair. The relationship between TGF‐β and FGF‐2 in wound repair is not understood.MethodsVIC confluent monolayers were wounded and treated with FGF‐2, FGF‐2 neutralizing antibody, TGF‐β neutralizing antibody and/or betaglycan antibody. Phosphorylated‐Smad2/3 (pSmad2/3) was localized at the wound edge (WE). Down‐regulation of pSmad2/3 protein expression was achieved via siRNA transfection.ResultsFGF‐2 treatment increased the number of VICs with nuclear pSmad2/3 staining at the WE compared to nontreated WE. Treatment with TGF‐β neutralizing antibody alone or with FGF‐2 present resulted in a similar decrease in nuclear pSmad2/3. Treatment with FGF‐2 neutralizing antibody alone or with FGF‐2 present showed a similar decrease in nuclear pSmad2/3; however the effect of FGF‐2 neutralizing antibody was less than that of TGF‐β neutralizing antibody. Incubation with betaglycan antibody inhibited FGF‐2‐mediated pSmad2/3 signaling. Down‐regulation of pSmad2/3 reduced the extent to which FGF‐2 promoted wound closure.ConclusionFGF‐2 promotes in vitro VIC wound repair, at least in part, through the TGF‐β/Smad2/3 signaling pathway. Supported by the Heart and Stroke Foundation of Ontario (grant NA6204) and the Canadian Institutes for Health Research (grant 84228).