Vascular Smooth Muscle Cell Mechanics During Cyclic Stretch: Effect of Serum and a Serum Substitute

Remodeling of arteries in response to altered loads is an area of intense interest to cardio-vascular clinicians and researchers. In humans, changes due to cardiovascular diseases (e.g. aortic dilatation) may occur slowly over many years, and mathematical models that describe the remodeling response are needed for predicting the course, and possible treatment, of these diseases. Recently, Humphrey and co-workers have proposed constrained mixture models [1] that consider local stresses in the arterial wall to be the sum of contributions from collagen, elastic fibers, and vascular smooth muscle cells (VSMCs). While numerous studies (e.g., [2]) have considered the active response of VSMCs in large arteries under quasi-static conditions, little is known about the mechanical response of VSMCs to continuous cyclic stretch. We have chosen 3-D bio-artificial tissue constructs as a model system in which to study the response of VSMCs to continuous cyclic stretch. However, VSMCs undergo a shift from a contractile phenotype to a de-differentiated phenotype during culture [3]. Some investigators have suggested that serum deprivation can induce re-differentiation toward a more contractile phenotype [4, 5]. The goal of our study was to compare the effect of incubation conditions on the active responses of VSMCs in 3-D tissue constructs to continuous cyclic stretch.