Modulation of Cell Coupling: Unknown Factors and New Strategies
Open AccessThe aim of this dissertation was to study how electromechanical coupling in cardiac tissue can be modified. The first project aimed to modulate proteins of the intercalated disc in order to facilitate the engraftment efficiency of stem cells. Surprisingly a small number of studies have attempted to modulate, either pharmacologically or genetically, the intercalated disc proteins of either host or grafted cells to facilitate engraftment efficiency. It was hypothesized that upregulation of N-cadherin in donor embryonic stem cells (ESC) can be an approach to alleviate clusterization and to enhance the adhesiveness of transplanted cells to the myocardium. To test this strategy a new line of mouse embryonic stem cells that constitutively overexpress N-cadherin (NCadR1 cells) was developed and characterized. These cells are more adhesive to cardiomyocytes and have a significantly higher expression level of connexin-43, suggesting the possibility for a high level of electrical engraftment. The second project aimed to create a novel three-dimensional in vitro model that more closely resembled cardiac tissue, by enhancing cardiomyocyte alignment into fibers and facilitating intercalated disc formation. Specifically, a new technique was developed that produces a net of three-dimensional cardiac fibers contracting in opposition to a compliant matrix. The fibers are fully accessible for physiological or epitope monitoring. Most importantly these fibers exhibit more matured intercalated discs. The developed method may be helpful to study cell engraftment into cardiac muscle, or to address developmental changes in cytoskeleton, myofibril or intercalated disc structures. Furthermore, because this three-dimensional model contains a mixed population of heart cells, it may serve as a useful model to assess cardiac drug toxicity. The third project aimed to explore how phthalate treatment affects the electromechanical coupling of cardiac layers. Phthalates are common plasticizers, used in a wide variety of household items and medical devices. Treatment of neonatal cardiomyocytes with clinically relevant concentrations of the most common phthalate, Di(2-ethylhexyl)phthalate (DEHP), was shown to functionally uncouple a cardiomyocyte network, resulting in asynchronous contractions. The observed physiological uncoupling in DEHP samples correlated with a diminished amount of connexin-43 protein and abrogated gap-junctional communication, as measured using a dye transfer assay. The marked uncoupling effect of DEHP, along with other observed effects of this compound on cardiac network behavior, represent a novel phenomenon which calls for further studies aimed at assessing this clinically relevant issue.
- All rights reserved
Notice to Authors
If you are the author of this work and you have any questions about the information on this page, please use the Contact form to get in touch with us.