Preservation of rat palatal scar tissue myofibroblasts in organ culture.

In order to modulate palatal scar tissue, especially its myofibroblastic component, there is a pressing need for an in vitro model of this tissue. In the present, study we established an organ culture model of the rat palatal scar tissue. After excision of palatal mucoperiosteum, explants from the developing immature scar tissue and from the normal palatal mucosa were used to observe myofibroblasts in vivo and their maintenance in organ culture. Explants were cultured at the gas-liquid interface in serum-free Waymouth's MB 752/1 medium and in a humid atmosphere containing 55% O2/5% CO2 in air at 37 degrees C for 3 days. Viability of the cultured explants was evaluated with morphological and histological criteria and BrdU incorporation. After organ culture, the scar tissue showed good preservation of the in vivo histology. The myofibroblasts and smooth muscle cells of the cultured scar tissues showed continuous expression of alpha-smooth muscle actin (alpha-SMA), mimicking the in vivo situation. In the normal tissues, only smooth muscle cells of the blood vessels expressed alpha-SMA. These results demonstrate that the established model provides a useful in vitro experimental tool for investigating the palatal scar tissue in general and its myofibroblasts in particular.