The effects of mechanical stimulation on controlling and maintaining marrow stromal cell differentiation into vascular smooth muscle cells.

For patients suffering from severe coronary heart disease (CHD), the development of a cell-based tissue engineered blood vessel (TEBV) has great potential to overcome current issues with synthetic graft materials. While marrow stromal cells (MSCs) are a promising source of vascular smooth muscle cells (VSMCs) for TEBV construction, they have been shown to differentiate into both the VSMC and osteoblast lineages under different rates of dynamic strain. Determining the permanence of strain-induced MSC differentiation into VSMCs is therefore a significant step toward successful TEBV development. In this study, initial experiments where a cyclic 10% strain was imposed on MSCs for 24 h at 0.1 Hz, 0.5 Hz, and 1 Hz determined that cells stretched at 1 Hz expressed significantly higher levels of VSMC-specific genetic and protein markers compared to samples stretched at 0.1 Hz. Conversely, samples stretched at 0.1 Hz expressed higher levels of osteoblast-specific genetic and protein markers compared to the samples stretched at 1 Hz. More importantly, sequential application of 24-48 h periods of 0.1 Hz and 1 Hz strain-induced genetic and protein marker expression levels similar to the VSMC profile seen with 1 Hz alone. This effect was observed regardless of whether the cells were first strained at 0.1 Hz followed by strain at 1 Hz, or vice versa. Our results suggest that the strain-induced VSMC phenotype is a more terminally differentiated state than the strain-induced osteoblast phenotype, and as result, VSMC obtained from strain-induced differentiation would have potential uses in TEBV construction.