Fibroblast Growth Factor-2 Promotes in Vitro Mitral Valve Interstitial Cell Repair through Transforming Growth Factor-beta/Smad Signaling

Transforming growth factor (TGF)-beta and fibroblast growth factor (FGF)-2 both promote repair in valve interstitial cell (VIC) injury models; however, the relationship between (TGF)-beta and FGF-2 in wound repair are not well understood. VIC confluent monolayers were wounded by mechanical injury and incubated separately or in combination with FGF-2, neutralizing antibody to FGF-2, neutralizing antibody to (TGF)-beta, and betaglycan antibody for 24 hours after wounding. Phosphorylated Smad2/3 (pSmad2/3) was localized at the wound edge (WE) and at the monolayer away from the WE. Down-regulation of pSmad2/3 protein expression via small-interfering RNA transfection was performed. The extent of wound closure was monitored for up to 96 hours. FGF-2 incubation resulted in a significant increase in nuclear pSmad2/3 staining at the WE. Neutralizing antibody to (TGF)-beta alone or with FGF-2 present resulted in a similar significant decrease in pSmad2/3. Neutralizing antibody to FGF-2 alone or with FGF-2 present showed a similar significant decrease in pSmad2/3; however, significantly more staining was observed than treatment with neutralizing antibody to (TGF)-beta. Incubation with betaglycan antibody inhibited FGF-2 mediated pSmad2/3 signaling. Wound closure corresponded with pSmad2/3 staining at the WE. Downregulation of pSmad2/3 via small-interfering RNA transfection significantly reduced the extent to which FGF-2 promoted wound closure. Fibroblast growth factor-2 promotes in vitro VIC wound repair, at least in part, through the (TGF)-beta/Smad2/3 signaling pathway. (Am J Pathol 2011, 178:119-127; DOI: 10.1016/j.ajpath.2010.11.038)