To this end, we developed such a system and used it for preliminary testing of the effects of variable stretch on mRNA expression of several intracellular and extracellular matrix (ECM)-related molecules www.selleckchem.com/products/lapatinib.html in a collagen-based construct (Gelfoam) seeded with neonatal rat lung fibroblasts. Results Device characterization Figure 1A shows the relationship between the input and output distances for cyclic stretches performed at 0.5 Hz. The linear fit has a slope of 0.977 and an R2 of 0.999 thus showing that the output distance was consistent and linearly related to the input distance over the entire range of the actuator stroke. Figure 1B shows the dependence of the output distance on frequency, ranging from 0.1 to 2 Hz. The output distance remained within 2% of the desired distance (5 mm) for all tested frequencies.

The repeatability of the stretch is shown in Figure 1C, where the solid line represents the stretch waveform at the beginning of a three hour stretch while the stars indicate the waveform at the conclusion of the stretch. The desired cyclic stretch had a frequency of 0.1 Hz and amplitude of 5 mm. The two curves are nearly identical, showing that the motion of the actuator was reproducible over the length of the experiment. Figure 1. The distance traveled by the linear guide is plotted against the prescribed travel distance and fit with a linear relationship (A). The frequency dependence of travel is shown for the maximum travel distance of the linear guide (B). … mRNA expressions Mechanotransduction involves the translation of forces from the extracellular space into the cell leading to cellular response.

To determine how variable stretch might modulate cell function we evaluated the relative expression of important ECM components (type 1 collagen, and lysyl oxidase (LOX)), cell surface ECM receptors (integrins and syndecan 4), a critical cytoskeletal component (��-smooth muscle actin) and vascular endothelial growth factor-A (VEGF) involved in maintaining cell viability and stimulating tissue repair. The expression level of each mRNA was evaluated at 0, 25, 50, and 75% variability. The monotonous sinusoidal (0% variability) condition had a sample size of 9, while all other conditions had a sample size of 3. Figure 2 shows the relative mRNA expressions of collagen 1�� and LOX for increasing levels of variability.

Both collagen 1�� and LOX mRNA levels were elevated with increased variability and this was statistically significant among the groups with p = 0.033 for collagen 1�� and p = 0.034 for LOX. Figure 2. Relative mRNA expression for collagen 1�� and lysyl oxidase at 25%, 50% and 75% variability, normalized to the 0% variability condition. Both collagen 1�� and lysyl oxidase show a statistically significant difference among … The relative expression of mRNA for ��-actin and VEGF are shown in Figure 3. Both molecules exhibited a decreasing trend in expression at 25% variability Brefeldin_A in strain.