Effects of ascorbate and B-aminopropionitrile on tendon fibroblast migration in vitro

Ascorbate (Asc) stimulates collagen synthesis and hydroxylation whereas beta-aminopropionitrile (BAPN) inhibits collagen cross-link formation. In this study, an in vitro model employing isolated chicken tendon biopsies (2 mm in dia.) in a fibrin clot has been used to examine the effect of Asc and BAPN on tendon fibroblast migration and proliferation. After 5 days in culture with either Asc (0.1 mM), or BAPN (0.5, 1.0, 2.0 mM), cell migration was measured using an automatic planimeter and cell proliferation was quantitated by 125IUDR incorporation into DNA. In cultures treated with Asc alone, cell migration was enhanced by approximately 33% compared to controls without ascorbate (5.9 mm2 vs. 4.4 mm2; p < 0.05) with no significant effect on cell proliferation. In contrast, cultures incubated with increasing concentrations of BAPN (0.5 - 2.0 mM) displayed a dose-dependent decrease (up to 9.6-fold at 2 mM) in fibroblast migration into the clot. The inhibitory effect of BAPN on cell migration was not due to a corresponding inhibition of fibroblast proliferation. These observations suggest that Asc enhanced collagen formation and thus allowed greater cell migration into the fibrin matrix. In contrast, in the absence of a mature, cross-linked collagen matrix following exposure to BAPN, cell migration was sub-optimal. These in vitro studies support the hypothesis that modulation of the collagen matrix may be a useful means of regulating tissue repair in vivo