Rigidity of collagen fibers affects smooth muscle cell morphology.

Dennis P. McDaniel, John T.Elliott, Kurt J. Langenbach, Alessandro Tona, and
Anne L. Plant

 

The fate of a cell is influenced by many external factors, including nutrient availability, mechanical factors, the presence of hormones and growth factors, and the composition of the insoluble proteins of the extracellular matrix. In the current study, we are examining the effect of physical properties of the extracellular matrix proteins on cellular morphology. A smooth muscle cell line obtained from rat aortic tissue was grown on thin films of collagen fibers formed on alkanethiol self ľassembled monolayers, a reproducible extracellular matrix developed in our laboratory. These thin films of collagen have been shown to be extremely uniform and to elicit a very reproducible range of cellular morphologies. Time-lapse phase contrast microscopy shows that smooth muscle cells are able to generate enough tension to significantly alter the collagen fiber arrangement in hydrated films. When these films are dried down for an extended period of time before seeding with cells, fiber movement is no longer observed, and a much different range of cellular morphologies is obtained. It is our hypothesis that the period of dehydration is increasing the rigidity of the fibers, and that this increased rigidity is responsible for the change in measured cellular morphology. We are currently exploring ways of quantitating the amount of fiber movement observed in live cell experiments. Future activities will be aimed at direct quantitation of fiber rigidity, and the development of methods to systematically vary the fiber rigidity to better investigate how mechanical features influence the cellular response.