Integrin-mediated cell adhesion to extracellular matrices regulates the organization, maintenance and repair of numerous tissues, and abnormalities in adhesive interactions are often associated with pathological states. Moreover, cell adhesive interactions with synthetic materials govern host responses to biomedical devices, biological integration of tissue-engineered constructs, and development of biotechnological cell culture supports. The adhesive process comprises integrin receptor binding to their extracellular ligand, integrin clustering, and assembly of discrete supramolecular structures containing cytoskeletal and signaling molecules. These focal adhesion complexes function as structural links and signal transduction elements between the cell and its extracellular environment. While significant progress has been attained in deciphering biochemical pathways regulating adhesion, the mechanical interactions between a cell and its environment remain poorly understood.
The objective of this project is to analyze the effects of nanoscale focal adhesion geometrical structure (cluster number, size, spacing) on cell adhesive force and focal adhesion signaling. It is hypothesized that the geometrical organization of the focal adhesion modulates adhesive force based on the "contact splitting" principle. "Contact splitting" mechanics explains how many small contacts can produce a higher adhesion force than one contact with equal contact area. The architecture of the adhesive interface will be modulated using various configurations of clustered nanopatterned adhesive islands and multi-valent ligands to alter integrin clustering and focal adhesion area and spacing. Integrin binding and focal adhesion assembly and signaling in fibroblasts will be quantified using biochemical and immunostaining techniques, and adhesion strength will be analyzed using our hydrodynamic spinning disk assay.
The proposed research will integrate robust quantitative assays, nanopatterning approaches, and unique cell biology reagents to precisely manipulate focal complex organization and biomolecular structure in order to analyze how these adhesive complexes generate adhesive forces. These studies will provide rigorous, integrated analyses of the contributions of nanoscale organization and structure to the generation and regulation of adhesive forces. These studies will generate a new understanding of the regulation of mechanical interactions between a cell and its extracellular matrix.
This project will also result in the advanced training of undergraduate and graduate researchers with unique analytical skills based on a multi-disciplinary, integrative perspective. One underrepresented minority student, either from Georgia Tech or our Atlanta University Center (AUC) Initiative, will be recruited every year to work in this project to encourage advanced education and future careers in science and engineering. The AUC is the world's largest consortium of African American private institutions of higher education, including Clark Atlanta University, Morehouse College, and Spelman College.
