Christopher Chen

Exploratory Study of Contractile Force in Cardiomyocytes

ABSTRACT
Cardiac disease is a leading cause of death and even though researchers  have been able to make extensive progress in different ways to study the human  heart in vivo. There is still a gap between in vivo and in vitro models that has not yet been totally bridged. In vitro models are simple enough to create controlled conditions but still cannot replicate the complex conditions that an in vivo model can provide. In this work we explored two methods of modeling heart function and disease… Using traction force microscopy in an established PDMS (PolyDiMethylSiloxane) device. We studied the difference in contractile force between a wild-type and a desmosome mutant cardiomyocyte cell line. With this device,  statistically significant reduction in contractile force due to mutation was noticed.  Then, scale up the model creating a protocol for a catheter balloon device was attempted. The scale up method allowed to replicate the in vivo environment more accurately. It was able to successfully maintain the new tissue attached to the device for up to 8 days. This finding opens a different way to relate a more accurate in vivo-like cardiac studies.

CONCLUSION
In this work we built an in-vitro device in a controlled environment to be able to test different heart diseases in the future. It was demonstrated that wild type, when uniformly contracted, has more force than mutants.

UNDERGRADUATE STUDENT
Domenica Passariello

GRADUATE STUDENT
Christos Michas

Biomimetic in Vitro Model to Reveal Endothelial-Fibroblast Interaction

ABSTRACT
This project explores the study of angiogenesis by investigating the interactions between endothelial and fibroblast cells in a two-channel microfluidic device. A critical role of angiogenesis occurs when vessels are damaged, for fibroblasts are essential connective tissue cells used to repair damages. Therefore, it was hypothesized that fibroblast induces the growth and sprouting of endothelial cells. To explore the different effects on endothelial cells sprouting, an experiment was conducted varying the concentration of fibroblasts. It was found that a greater concentration of fibroblast resulted in a greater number of endothelial cell sprouts, its length, and node formations. This ensures that the fibroblasts have the ability to stimulate cell growth; which could potentially be used in other applications such as repairing damaged vessels.

CONCLUSION
After experimenting with different concentrations of fibroblast, the results confirmed that fibroblast induces endothelial cell proliferation. As expected, the greater concentration of fibroblast correlated with the longest endothelial sprouting growth. Within the control, it could be observed that the endothelial cells did not sprout to the extent of the other devices, for they did not have a structure nor any interconnection. In contrast, as the concentration of fibroblast increased, the endothelial cells sprouted extensively, developing vessel-like structures between the two channels… A possible explanation behind such observation is that fibroblasts contain characteristics that stimulate the bonding of VEGFA with VEGFR2 which increases the tip cells proliferation. When a tip cell is selected, the activities of VEGFR2 is inhibited, preventing neighboring cells from proliferating as well. Therefore, if fibroblast interferes the inhibition, endothelial cells will continue to grow and sprout. Hence, the more presence of fibroblast around endothelial cells, encourages more neighboring cells to sprout alongside each other.

UNDERGRADUATE STUDENT
Shola Onissema-Karimu