The regulation of valve interstitial cell (VIC) function in response to tissue 
injury and valve disease is not well understood. Because transforming growth 
factor-beta (TGF-beta) has been implicated in tissue repair, we tested the 
hypothesis that TGF-beta is a regulator of VIC activation and associated cell 
responses that occur during early repair processes. We used a well-characterized 
wound model that was created by mechanical denudation of a confluent VIC 
monolayer to study activation and repair 24 hours after wounding. VIC activation 
was demonstrated by immunofluorescent localization of alpha-smooth muscle actin 
(alpha-SMA), and alpha-SMA mRNA levels were quantified by real-time polymerase 
chain reaction. Proliferation and apoptosis were quantified by bromodeoxyuridine 
staining and terminal deoxynucleotidyl transferase dUTP nick end labeling, 
respectively. Repair was quantified by measuring VIC extension into the wound, 
and TGF-beta expression was shown by immunofluorescent localization of 
intracellular TGF-beta. Compared with nonwounded monolayers, VICs at the wound 
edge showed alpha-SMA staining, increased alpha-SMA mRNA content, elongation 
into the wound with stress fibers, proliferation, and apoptosis. VICs at the 
wound edge also showed increased TGF-beta and pSmad2/3 staining with 
co-expression of alpha-SMA. Addition of TGF-beta neutralizing antibody to the 
wound decreased VIC activation, alpha-SMA mRNA content, proliferation, 
apoptosis, wound closure rate, and stress fibers. Conversely, exogenous addition 
of TGF-beta to the wound increased VIC activation, proliferation, wound closure 
rate, and stress fibers. Thus, wounding activates VICs, and TGF-beta signaling 
modulates VIC response to injury.