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SEED: Micromechanics of Cell Adhesion


The purpose of the Seed group is to pursue joint research in an emerging area of biological systems, cell adhesion, in which mechanics plays a key role.  The Seed project integrates our established expertise in mechanics of materials with expertise in biology and biophysics.  This interdisciplinary project includes faculty drawn from mechanics, materials, biology and physics. This topical area is a natural outgrowth of prior efforts within the MRSEC program, particularly in thin film studies.  The fields of biophysics and biomedical sciences, on the other hand, have undergone a revolution in observational methodologies in the past decade or two.  As a direct consequence, amazing quantitative data on cell adhesion at the molecular level is emerging.  On the basis of shared interests crossing disciplinary boundaries, this faculty group has literally self-assembled with the aim of advancing this multi--disciplinary activity at Brown.  Results of the effort are expected to shed new light on the basic processes of life and on treatment of disease, on the possibility of harnessing the natural functions of cells in small-scale material processing, and on strategies for engineered adhesions that mimic natural cell processes.

Adhesion plays a central role in biological processes of cells that are essential for life in animals: morphogenesis, angiogenesis, inflammatory response and wound healing.  A long held view was that adhesion was regulated by physical forces, akin to those involved in contact of clean solid surfaces.

During the past couple of decades, however, the basis for cell adhesion has come to be understood mainly in terms of molecular interactions.  The interaction energies resulting from molecular interactions between biological surfaces of direct relevance to cell adhesion and the experimental methods available to measure them have been reviewed recently.

Numerous factors, beyond the small size scale, present challenges for development of definitive experiments and quantitative material models at the cell level.  The relatively low elastic moduli of the materials involved lessens the influence of large-scale elastic energies compared to other factors involved in interactions. Weak chemical bonding implies significant entropic influences in interactions, and random walk sampling mediated by gradient-driven diffusion sets the time scale for various processes. In addition, the time-dependent interaction of the proteins bound in the cell membrane with the cytoskeleton is coupled to the cell's environment.

In the short term, quantitative models are needed for the interpretation of laboratory observations in terms of the fundamental mechanisms at work and for drawing inferences from data.  A longer term goal is to understand the collective behavior of cells in terms of their environments, particularly those mechanical interactions that are potentially key to the technological objectives of tissue engineering.  This project requires the perspectives of molecular biology and statistical mechanics as essential components.