To clarify the mechanisms underlying declines in wound contraction caused by basic fibroblast growth factor (bFGF) and the role of autologous fibroblasts in modulating wound healing, we have examined the expression of alpha-smooth muscle actin (alpha-SMA) and apoptosis in a model of wound healing using collagen sponges with and without bFGF (1 microg) and/or fibroblasts (1 x 10(6) cells/cm(2)) applied to experimentally produced full-thickness skin wounds in rats (n=10 for each group). At 7 days postoperatively, wounds filled with a fibroblast-seeded collagen sponge (fibroblast-seeded group) displayed a greater area of collagen sponge and a smaller area of fibroblasts compared with control wounds filled with collagen sponge alone (control group). Therefore, seeding of fibroblasts in the dermal substitute might retard degradation of the collagen sponge, inhibiting fibroblast infiltration into the substitute. By day 14, wounds filled with bFGF-treated collagen sponge without fibroblast seeding (bFGF group) displayed decreased alpha-SMA expression and significantly increased apoptosis compared with other wounds. Double staining revealed that apoptosis in alpha-SMA-positive fibroblastic cells was significantly increased in the bFGF group, suggesting that bFGF treatment is a potent stimulator of myofibroblast apoptosis. Furthermore, morphometric analysis demonstrated the significant decrease in the level of wound contraction and the degree of mature collagen bundle formation in the bFGF group by day 42. The bFGF group also showed increased bFGF expression in macrophages by day 28. These results suggest that bFGF administration to an artificial dermis promotes apoptosis of alpha-SMA-positive fibroblastic cells and inhibits alpha-SMA expression in the treated wound, thus reducing wound contraction.

To examine the effects of basic fibroblast growth factor (bFGF) on the inhibition of alpha-smooth muscle actin (alpha-SMA) expression in dermal fibroblasts, we have established two dermal myofibroblastic cell lines positive for alpha-SMA (rat myofibroblasts [RMF] and rat myofibroblast-like [RMFL] cells) and one fibroblastic cell line negative for alpha-SMA (rat fibroblasts cells) as a model of fibroblast differentiation. In contrast to the increased expression of alpha-SMA in RMF and RMFL cells, irrespective of transforming growth factor-beta1 treatment, bFGF induced a decrease in alpha-SMA expression in the myofibroblastic cells and the reduced expression patterns of alpha-SMA differed between cells, as demonstrated by Western blot and reverse transcription polymerase chain reaction analyses. Along with the inhibition of alpha-SMA expression by bFGF, the RMF and RMFL cells also showed different activated expression of extracellular signal-regulated kinase 1/2, suggesting the involvement of extracellular signal-regulated kinase 1/2 activation in the down-regulation of alpha-SMA expression in myofibroblasts. Furthermore, an in vivo study demonstrated that bFGF administration markedly decreases the area that is positive for alpha-SMA expression in the treated wounds after day 18. In contrast, bFGF administration significantly increased the number of terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL) staining and alpha-SMA-positive cells at days 10 and 14, and reduced the double-positive cells rapidly after day 18. Collectively, the current investigation identified bFGF as a potent stimulator for the reduction of the myofibroblastic area in vivo, presumably because of its effects on the down-regulation of alpha-SMA expression as well as rapid induction of apoptosis in myofibroblasts.

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In non-severe frail octogenarians with AF taking OACs, having a low BMI was the most significant factor associated with the development of bleeding.

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