Acceleration of rat salivary gland tissue repair by basic fibroblast growth factor

A model of atrophic rat submandibular gland was used to examine the ability of basic fibroblast growth factor (bFGF) to accelerate tissue repair. The gland duct was separated carefully from associated blood vessels and nerve, and ligated with a 8-0 suture under a surgical microscope. Two weeks after ligation, the glandular tissue showed severe atrophy and weight loss (to 26% of that in a sham-operated group). Thereafter, the ligature was removed and various amounts of bFGF, isoproterenol or saline were instilled retrogradely through the duct. Both isoproterenol and bFGF increased cell proliferation significantly. bFGF accelerated the proliferation of various cell types, including both acinar and ductal. The proliferative effects of bFGF peaked at a dose of 1 ng/gland. When bFGF (1 ng/gland) was administered to the atrophic gland, its weight increased to 125% of the glands in saline-treated control animals after 2 weeks. The effects of bFGF were also examined in normal submandibular glands: bFGF stimulated cell proliferation, but the effective concentration was at least 50 times higher than that required in the atrophic gland. The results from immunohistochemical tests against anti-FGF receptor-type 1 antibody demonstrated increased immunoreactivity in the damaged gland, which might be involved in the difference in the response to bFGF between damaged and normal glands. Overall, the results indicate that bFGF can accelerate tissue repair in salivary gland.