PURPOSE: Fibrocontractile disease encompasses a broad spectrum of disorders which affects nearly 80 million people worldwide annually. There are no effective treatments and preventative strategies are marginally effective. The role of the investigation was to verify the function of non muscle myosin II in promoting fibroblast and myofibroblast contractility as it relates to fibrocontractile disease progression. .
METHODS & MATERIALS: Fibroblasts were enmeshed in collagen lattices and exposed to increasing concentrations of the non muscle myosin II inhibitor, blebbistatin. Experiments were repeated using varying collagen concentrations, serum concentrations, and cell densities. Fibroblast monolayers were wounded and allowed to heal in the presence of increasing concentrations of blebbistatin. ANOVA was used to determine statistical significance between groups (significance p< .05). Immunofluorescence was used to analyze alpha smooth muscle actin and beta actin stress fiber formation in the presence of blebbistatin. Western Blotting was used to quantify myofibroblast formation after exposure to blebbistatin. Immunohistochemistry, with blinded observer analysis, was used to compare non muscle myosin II expression in human scar versus unwounded skin.
RESULTS: Blebbistatin inhibited collagen lattice contraction in a dose-dependent, reversible manner (p<0.05). Alteration of cell density, collagen concentration, or serum concentration did not alter blebbistatin's effects. Blebbistatin significantly inhibited wound healing in a dose dependent fashion (p< 0.05). Inhibition of non muscle myosin II significantly (p<0.05) prevented myofibroblast formation and diminished actin stress fiber formation. Non muscle myosin II is robustly expressed in scar compared to unwounded tissue (p< 0.05).
CONCLUSION(S): The presented results indicate that selective inhibition of non muscle myosin II prevents collagen matrix contraction and cell migration in a dose-dependent fashion. Blockade of non muscle myosin II prevents expression of the contractile phenotype. Non muscle myosin II is significantly transcriptionally upregulated in scar compared to normal tissue. Non muscle myosin II may likely be the primary motor protein in fibroblasts and myofibroblasts that regulates fibrocontractile disease and thus be a target for preventing disease progression.