Dental pulp cell stimulation via integrin targeted inductive nano-therapeutics

Abstract

Current approaches to dental pulp regeneration rely on poorly understood mechanisms to enhance formation of reparative dentin and are limited by the rapid inflammatory response in the dental pulp and resultant death of most pulpal tissue. The central hypothesis: dendrimers, functionalized with cyclic arginine-glycine-aspartic acid (RGD) peptides, will bind to integrin receptors found on cells in the dental pulp and simultaneously deliver molecules that enhance regeneration resulting in new tissue formation. Objectives: 1. Identify integrin receptors on dental pulp cells(DPC) and in dentin and mimic ligands for those receptors in the synthesis of targeted-multifunctional dendrimer conjugates. 2. Establish mechanisms for integrin-mediated stimulation of dental-pulp cells and identify molecular cues that enhance the regenerative capacity of these cells. Methods: Analyze RNA and protein expression in dental pulp cells, dental pulp stem cells and mineralized dentin as a result of integrin-targeted dendrimer delivery. In addition, phenotypic changes and well as markers for dental differentiation measured via western blot, immunohistochemistry and RT-PCR were examined. Results: The receptor for RGD ligand was highly expressed in DPC as well as the pre-dentin of tooth organs when analyzed via flow cytometry and confocal microscope. Binding of G5 RGD was eliminated when cultured were pre-incubated with free RGD peptide. Both RNA transcription and protein expression of dental specific markers was increased on G5-RGD binding. Conclusion: RGD binding may participate in determine the cell fate of DPC. This receptor may be an important target for dental therapeutics. This project will promote the development of novel therapeutic dental nano-materials with the goal of reducing tooth loss due to disease or injury. In addition, this new strategy for targeted delivery of regenerative molecules via integrin-targeted nano-polymers may be broadly applicable in regenerative medicine in conditions in which ligands specific to the microenvironment can be established.