Recent investigations on regeneration of the periodontium have attempted to define factors involved in the formation of a new connective tissue attachment. One essential biological event involved in tissue regeneration is directed cell migration (chemotaxis). Extracellular matrix proteins have been shown to influence chemotaxis, cell proliferation and differentiation. Recently, the extracellular matrix proteins, fibronectin (FN) and laminin (LM), and the polypeptide, endothelial cell growth factor (ECGF), have been shown to stimulate a variety of biological processes. Current assay systems which attempt to define cell migration are the Boyden chamber assay and a random cell migration assay. Neither assay system adequately defines in vivo cell migration. Here we present a new in vitro assay system that tests the capacity of several biological response modifiers applied on dentin to stimulate a chemotactic and proliferative response from various cell types. The assay system consists of two types of assays. Assay I measures the chemotactic activity of test substances bound to dentin. In this assay cells must actively move through a filter (Nuclepore) towards a factor bound to dentin. Assay II examines the ability of dentin-bound biological response modifiers to stimulate directed movement and proliferation of cells on dentin surfaces. We report that periodontal ligament (PDL) cells migrate towards FN and ECGF; that PDL cell migration is enhanced when dentin is preconditioned with tetracycline HCl; that PDL cells have an increased proliferative response when dentin is conditioned with both FN and ECGF; that gingival epithelial cells have increased migratory and proliferative responses when LM is used to condition dentin; and that there is a reciprocal utilization of biological response modifiers by gingival epithelial cells and PDL cells.
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