Lectins inhibit periodontal ligament fibroblast attachment, spreading and migration on laminin substrates

The ways in which carbohydrate signals from the extracellular matrix influence the responses of periodontal ligament (PDL) fibroblasts are essentially unknown. The purpose of this study, using video digital image analysis, was to examine the effects of lectins on the attachment, spreading and migrational responses of rat periodontal ligament fibroblasts on the highly glycosylated glycoprotein laminin (LN) in vitro. PDL fibroblasts were isolated from rat molar teeth and grown in culture. Bound LN and control substrates (bovine serum albumin and untreated plastic) were incubated with solutions of either wheatgerm agglutinin (WGA), specific for N-acetylglucosamine, or concanavalin A (ConA), specific for mannose, in 96-well plates. Unbound lectin was rinsed away and 10.0 x 10(3) cells were seeded per well and allowed to attach for 1.5 h. Incubation of LN substrates with WGA, prior to the addition of any cells, inhibited PDL fibroblast binding more than 5-fold. ConA, however, had no effect on cell binding but inhibited mean individual cell spreading nearly 3-fold under similar assay conditions. The effects could be prevented by adding each lectin's respective specific sugar. The lectins had no effects on the control substrates. In a 24-h cell migration assay WGA and ConA both significantly inhibited migration of PDL fibroblasts. It is likely that WGA inhibited cell attachment and cell migration, by binding to oligosaccharides and blocking access to adjacent polypeptide cell recognition sequences on LN. The results from the ConA experiments, where binding was allowed but spreading was severely inhibited, suggest a possible informational role for the carbohydrates present on LN.