039), whereas VEGF nearly reached statistical significance (p = 0.066). Figure 3. Relative mRNA expression for ��-actin and VEGF at 25%, 50% and 75% variability, normalized to the 0% variability condition. ��-actin selleck kinase inhibitor shows a statistically significant difference among the treatment groups (p = 0.039), while … The expression of cell surface ECM receptors syndecan-4, ��1 and ��3 integrins is shown in Figure 4. Although ��1 and ��3 integrins did not show a statistically significant difference among groups (p = 0.075 and 0.260 respectively), syndecan-4 displayed a strong difference among groups (p = < 0.001). Furthermore, the mRNA level at 25% variability was different from the 0%, 50% and 75% variability conditions and the 0% variability condition was also statistically different from the 50% and 75% variability groups.
Figure 4. Relative mRNA expression for syndecan-4, ��1 integrin and ��3 integrin at 25%, 50% and 75% variability, normalized to the 0% variability condition. Syndecan-4 mRNA levels are statistically significant (p < 0.001), ... Discussion Cells in the body receive mechanical stimuli caused by the stresses and strains of locomotion, breathing, and due to various other physiological activities such as the heart pumping blood. The deformations that cells are exposed to are always irregular. For example, both the tidal volume of breathing7 and the ejection volume by the heart vary from cycle to cycle.11 Consequently, the mechanical stimuli that cells are exposed to within the ECM of the lung and the blood vessels also vary from cycle to cycle.
Thus, it is likely that cells are tuned to recognize and respond to these variable mechanical inputs. In order to determine how such variability in strain might affect the expression of key ECM and cell related molecules, we designed, built and tested a uniaxial stretching device that can mechanically stimulate up to six tissue pieces or constructs at a time, delivering cycle to cycle variability. Although similar uniaxial stretchers exist in the literature,9,10 this is the first study to apply cycle-by-cycle variability in strain and frequency. In this study, we developed a device that is robust and can deliver reliable strains for long durations in the controlled environment of a cell incubator.
Additionally, our preliminary exploration with the device suggests that variable stretch patterns can influence the expression of mRNA for several key molecules known to play important roles in cell-ECM interactions. Device characteristics Although several uniaxial stretchers have been introduced some of which are also commercially Brefeldin_A available, this is the first device to allow the user to apply variability of strain on a cycle-by-cycle basis. Our stretcher is designed as a high throughput system that can stretch up to six samples under the same mechanical conditions while allowing for different biochemical conditions in different wells.