Hookway, T. | Search bioRxiv

bioRxiv2024

Exogenous ECM in an environmentally-mediated in vitro model for cardiac fibrosis

Few clinical solutions exist for cardiac fibrosis, creating the need for a tunable in vitro model to better understand fibrotic disease mechanisms and screen potential therapeutic compounds. Here, we combined cardiomyocytes, cardiac fibroblasts, and exogenous extracellular matrix (ECM) proteins to create an environmentally-mediated in vitro cardiac fibrosis model. Cells and ECM were combined into 2 types of cardiac tissues-aggregates and tissue rings. The addition of collagen I had a drastic negative impact on aggregate formation, but ring formation was not as drastically affected. In both tissue types, collagen and other ECM did not severely affect contractile function. Histological analysis showed direct incorporation of collagen into tissues, indicating that we can directly modulate the cells ECM environment. This modulation affects tissue formation and distribution of cells, indicating that this model provides a useful platform for understanding how cells respond to changes in their extracellular environment and for potential therapeutic screening.

bioengineering↗

bioRxiv2024

Short-term Electrical Stimulation Impacts Cardiac Cell Structure and Function

Induced pluripotent stem cell derived cardiomyocytes (iPSC-CMs) are used to model cardiac development and disease. This requires a robust population of mature CMs and external stimuli to mimic the complex environment of the heart. In effort toward this maturation, previous groups have applied electrical stimulation (ES) to CMs with varying results depending on the stimulation duration, frequency, and pattern. As such, there is uncertainty surrounding the timeline on which stimulated iPSC-CMs begin to show early signs of maturation in comparison to their non-stimulated counterparts, leaving room for additional research into when hallmarks of maturity-such as hypertrophy and changes to sarcomere structure-develop in CMs. Here, we introduce a low-cost custom bioreactor capable of delivering tunable electrical stimulation to standard 2D cell monolayers. We show that, after exposure to short-term ES, stimulated CMs express early signs of maturation compared to the non-stimulated control. The changes to contractility and protein expression indicate that the cells undergo hypertrophy in response to short-term ES, but they do not develop transverse-tubules, which is a key component of a fully mature CM structure. Therefore, while early signs of maturation are present after a short stimulation regimen, additional cellular structures must develop to reach complete maturation. We have shown that our custom electrical stimulator can be easily integrated with standard in vitro cell culture platforms to obtain measurable changes to cells, exhibiting its potential for promoting crucial CM maturation for cardiac tissue engineering applications.

bioengineering↗