Dentine and Pulp Matrix Mediated Pulp Cell Migration

Pulp stem/progenitor cell recruitment to sites of injury represents one of the early events in tissue regeneration within the dentine-pulp complex. We have recently demonstrated that both intact and partially degraded extracellular matrix (ECM) molecules from dentine and pulp stimulate cell migration in a trans-well assay although the signalling of these events is not well understood. Objectives: This study has aimed to quantitatively image pulp cell migration in response to dentine and pulp ECM preparations using time-lapse microscopy and to investigate the cellular pathways involved in mediation of pulp cell migration. Methods: Dentine and pulp ECM preparations were isolated with 10% EDTA, pH7.2 and sequential use of 0.5M-NaCl, pH11.7 and 0.1M tartaric acid, pH2.0 respectively with protease inhibitor inclusion throughout. Cell migration, in an agarose spot assay (ECM molecules at 0.1 μg/ml), was imaged microscopically using a Cell-IQ time-lapse imaging chamber over a 36 hour period and the number of cells migrating was quantified. Inhibition of cell migration was examined in a trans-well assay using c3 transferase [Y-27632], a specific inhibitor of the Rho-GTPase family of molecules. Results: Time-lapse imaging showed stimulation of pulp cell migration (cell numbers and distance of migration) within agarose spots containing dentine and pulp ECM preparations. Inclusion of the c3 transferase inhibitor in trans-well migration assays using dentine ECM preparation resulted in the inhibition of cell migration. Conclusions: ECM molecules from dentine and pulp may be important mediators for pulp cell migration and recruitment, thereby facilitating regenerative events after injury. The Rho-GTPase family of molecules are key to the intracellular signalling cascade for the dentine ECM mediated cell migration.