Combinatorial Metal Oxide Substrates to Enhance Osteogenic Stem Cell Functions

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DESCRIPTION (provided by applicant): The overall objective of this project is to develop a foundation for a biomaterial screening strategy based on combinatorial materials science. This approach will provide substrates with a range of subtle changes in surface properties and composition. The efficacy of these novel material formulations will be determined in vitro using cell-culture models and by conducting a systematic investigation of the effects of the elemental composition of the biomaterial surface chemistry and topography on mesenchymal stem cell (MSC) differentiation and functions pertinent to new bone formation. The central hypothesis is that the metal oxide surface of the material substrate modulates the type, distribution and conformation of adsorbed proteins, these proteins direct and modulate subsequent cell interaction and function pertinent to new tissue formation. Specific Aim 1: Develop metal oxide substrates based on titanium that contain gradients of three other metals used as implant materials. It is hypothesized that, annealing by plasma-enhanced chemical vapor deposition, will generate concentration gradients using thin films of variable thickness sputtered onto Ti substrates. Specific Aim 2: Determine the type, distribution and conformation of select serum and/or ECM adhesive proteins such as collagen type I, fibronectin, laminin, and vitronectin, adsorbed onto the novel material substrates prepared by the research activities pertinent to Specific Aim 1. Specific Aim 3: Assess the osteogenic differentiation of MSCs onto the nanostructured substrates. It is hypothesized that following adhesion, MSCs migration will be affected by the surface gradients to regions on the substrate surface where select proteins had adsorbed and, most importantly, exhibit appropriate domains which promote subsequent cell adhesion and functions pertinent to new tissue formation. The proposed research is fundamentally different from past and current approaches in that it will develop a new process that will allow high-throughput testing of multiple material formulations of various stoichiometric combinations. This research is expected to achieve the following: (1) elucidate aspects of protein adsorption and adhesion and function of cells on the novel substrates; and (2) establish the potential of these metal oxide substrates as a high-throughput cytocompatibility assessment platform. PUBLIC HEALTH RELEVANCE: With a U.S. Prosthetic Implant market of about $1 billion a year and growing at a rate of 10% a year, any improvement in osseointegration and life of the prosthetic implant will have a drastic economic effect, especially if one takes into consideration that up to 30% of the implants in procedures such as hip replacement do not show appropriate osseointegration. The proposed project aims to improve the number of candidate biomaterials screened for improved osseointegration by investigating the effect of the material surface properties and protein adsorption on osteogenic mesenchymal stem cell behavior, using state of the art surface characterization and gene expression technologies.