Periodic Reporting for period 4 - MechanoSignaling (Predicting cardiovascular regeneration: integrating mechanical cues and signaling pathways)
Berichtszeitraum: 2023-07-01 bis 2024-12-31
Cardiovascular disease (CVD) remains a major cause of morbidity and mortality worldwide. Regenerative medicine has the potential to revolutionize healthcare and reduce the social and economic burden of CVD, as it aims at full restoration of tissue function through regeneration (cure instead of care). Cardiovascular tissue engineering (CVTE) is a promising example of regenerative medicine, aiming at the replacement of diseased or malformed cardiovascular tissues, e.g. blood vessels and heart valves, by (ultimately) biological substitutes to restore, maintain, or improve tissue function. Although promising results have been obtained, previous CVTE studies have seen limited success in terms of replicating the physiological, tri-laminar tissue organization of blood vessels and heart valves. As a poor replication of physiological tissue organization often translates into poor tissue functionality, we need to improve our understanding of cardiovascular regeneration to force breakthroughs and accelerate the clinical translation of CVTE. Due to the complexity of the processes underlying regeneration, computational models that can predict regeneration are necessary to predict which strategies may lead to successful outcomes. Within this context, modeling how the hemodynamic loads provided by the blood pressure regulate cardiovascular regeneration has received vast attention over the past years. However, modeling signaling pathways that regulate communication between cells and the emergence of global tissue organization in the setting of CVTE has remained a rather unexplored area. The overall aim of the current project is to obtain a mechanistic understanding of how the Notch signaling pathway, a relevant pathway in cardiovascular development and remodeling, drives the development of tissue organization in engineered cardiovascular tissues under the influence of mechanical cues induced by hemodynamic loads. For this, we perform systematic experiments to understand and quantify how Notch signaling between cells depends on mechanical stimuli, and how it directs tissue development and remodeling. Simultaneously, we develop computational models to analyze the experimental results, and predict cardiovascular regeneration and the role of Notch signaling in relevant CVTE scenarios.
We performed experiments to assess to what extent the Notch signaling pathway can steer the intracellular organization of vascular cells and their ability to produce proteins that become part of the extracellular tissue organization. Specifically, we subjected cells to various degrees of deformation to understand and quantify how Notch signaling depends on the mechanical cues that cells experience, and how such changes in Notch signaling correlate with changes in intracellular organization and protein production. The causative effect of Notch in this was determined via systematically inhibiting or stimulating Notch signaling. Regarding the development of computational models, we firstly developed a model that can describe the Notch signaling interactions between cells. This model was used to demonstrate that the organization of cells does not have a major impact on the resulting Notch signaling if a certain protein in the Notch pathway is dominating the signaling interactions. As a next step, we coupled this Notch signaling model to a continuum mechanics model of a blood vessel, which allowed us to understand how mechanical stresses and strains induced by the blood pressure regulate Notch signaling, and how Notch in turn directs tissue development and adaptation. We used this model to show how hypertension may lead to changes in Notch signaling in blood vessels. In a next study, we demonstrated how such changes in Notch signaling can give rise to functional tissue adaptation in response to the increased blood pressure. Finally, we developed a computational model to estimate the stresses and strains in tissue-engineered heart valves, with the aim to elucidate the role of (local) mechanical cues in regulating tissue development and adaptation as observed in recent experiments.
Notch signaling plays an essential role in cardiovascular development and adaptation, and is particularly known for its potential to regulate the emergence of macroscopic tissue organization (e.g. layer formation). Mechanical cues are well-known to regulate cardiovascular adaptation as well, and there is increasing evidence that the Notch pathway is mechanosensitive. Yet, also since the start of this project, no computational models have been developed to explore how this interplay between mechanical cues and Notch signaling can be leveraged to improve the organization of engineered cardiovascular tissues. The experimental and computational results so far were obtained according to the original project plan that is still beyond the state of the art. For the remaining part of the project, we aim to extend our experimental work towards investigating Notch signaling in more complex and realistic mechanical conditions. Furthermore, we will determine how Notch signaling affects the emerging tissue composition and organization under various mechanical conditions, and how these results can be tuned via manipulating Notch signaling. For the computational part of the project, we aim to finalize the development of our multiscale computational framework that describes tissue development/adaptation as determined by mechano-regulated Notch signaling. Next, we aim to apply the computational framework to analyze and understand the outcomes of previous CVTE studies (blood vessels and heart valves), and predict how the results could be improved to obtain functional tissue organizations via changing the initial construct properties. If successful, the proposed designs have the potential to force an important breakthrough by ensuring the establishment of a functional tissue organization in engineered cardiovascular tissues, which is key to ensure safe clinical translation of cardiovascular tissue engineering.