BME students present research in Phoenix
October 27, 2017

Honors students get hands-on research experience with faculty mentors, and are encouraged to present their research on and off campus, including at professional conferences. The Honors College provides support for our students who present their research at regional, national and international academic meetings. Participation at these conferences provides an opportunity for students to communicate their research to others in their field, network with undergraduate researchers and faculty, and expand their understanding of their field of research.

This month, four Honors students attended the Biomedical Engineering Society’s Annual Meeting in Phoenix: (left to right, above) Keerthana Shankar, Andy Vo, Tien Comlekoglu and Vrishti Phadumdeo.

Tien Comlekoglu, working with Professor Seth Weinberg, presented “Membrane Capacitive Memory Suppresses Alternans, Promotes Spontaneous Activity, and Alters Conduction in a Fractional-Order Minimal Cardiomyocyte Model.”

Cardiomyocyte electrical activity is typically modeled using ideal parallel capacitor-resistor circuit networks. However, studies have suggested that the passive properties of cell membranes may be more appropriately modeled with non-ideal circuit elements, in which the current-voltage relationship is governed by fractional-order dynamics that introduces capacitive memory effects, i.e., dynamics are influenced by the prior membrane potential history. This study considered the effects of fractional-order membrane dynamics on important cardiac electrical responses in both single cardiac cells and one-dimensional cardiac tissue. In particular, they investigated properties of cardiac alternans, a beat-to-beat alternation in the action potential duration (APD); spontaneous activity; and electrical conduction.

The results suggest that capacitive memory, reproduced by a fractional-order model, may play a role in both alternans formation and suppression in both APD and conduction velocity, and pacemaking.

Vrishti Phadumdeo, who also worked with Dr. Weinberg, presented “Heart Rate Variability Alters Cardiac Repolarization and Electromechanical Dynamics.”

Heart rate continuously varies for many reasons, including autonomic regulation, circadian rhythm, and stochasticity in cardiac pacemaking. The cardiac action potential depends on both heart rate and intracellular calcium signaling, a complex relationship as heart rate variability (HRV) also influences calcium signaling. At fast heart rates, the action potential duration (APD) and intracellular calcium can experience an arrhythmogenic phenomenon termed alternans, a beat-to-beat alternation. Alternans in a cardiac cell can be electromechanically concordant (EMC) or discordant (EMD), when APD and peak calcium are in-phase or out-of-phase, respectively.

In their study of how HRV alters the generation of such alternans and electromechanical properties, Vrishti’s findings suggest that HRV suppresses alternans and may provide a critical mechanism to repress arrhythmogenic conditions.

Keerthana Shankar, who worked with graduate student Bethany M. Young and Professor Rebecca L. Heise, presented “Novel Airway Epithelium Model Using Electrospun Decellularized Lung Extracellular Matrix.”

The lung airway wall consists of several layers with different cell types organized in a three-dimensional matrix. In order to investigate cell behavior and morphology within the airway through in vitro models, electrospinning may be used to create 3D scaffolds. Traditionally, electrospun scaffolds are composed of man-made polymers, but naturally-derived extracellular matrix polymers may promote more physiologically accurate cell behavior. The objective of this study was to determine optimal scaffold parameters that promote physiologically relevant interaction of cell types and their respective extracellular matrix environments. By doing so, a relevant modeling platform can be created for the airway to allow for more accurate modeling of diseases in vitro, and for the creation of potential replacement grafts.

Keerthana’s research determined that “the creation of a scaffold with multiple environments specific to each cell type forms a controlled and physiologically relevant in vitro model of the airway, thus decreasing dependence on animal models.”

 Andy Vo, who worked with Kelly Hotchkiss and Rene Olivares-Navarrete, presented “Effect of Podosome Inhibition on Macrophage Activation on Titanium Biomaterials.”

Implanting a biomaterial to treat or replace damaged tissue elicits an immune reaction first to the surgery and second to the material itself. Macrophages are among the first cells to interact with a biomaterial surface, releasing compounds to create a microenvironment favoring prolonged inflammation and fibrous encapsulation or wound healing and regeneration. Macrophage migration is supported by small actin-rich ring structures known as podosomes that create small footholds for macrophages to adhere to and move through tissues to the site of injury. Once at the implant surface, these structures may also play a role in recognizing differences.

Andy’s research group concluded that inhibition of podosome formation increased expression of pro- and anti-inflammatory markers compared to the untreated control on tissue culture polystyrene. Their data suggest that podosomes play an important role in the ability of macrophages to sense differences in surface properties.

Other students who have received travel grants this year to present their research include Justin Yirka, who attended the 20th Annual Conference on Quantum Information Processing in  Seattle in January, and Christine Aubry, who presented at the Southern Nursing Research Society in Dallas in February. Harshita Nangunari will present “Assessing the antidepressant-like effects of the (R) and (S) isomers of the atypical antipsychotic amisulpride in C57BL/6 mice” at the upcoming Society for Neuroscience conference in Washington, D.C., in November. And Divya Krishna will present "Effects of Astrocyte Conditioned Media and cAMP on Blood-Brain Barrier Integrity in an in vitro model" at the 7th Annual oSTEM Conference in Chicago, also next month.

To be eligible for a travel grant, students must present their research in either a poster or oral presentation, their names must appear in the conference abstract or proceedings, and VCU and the Honors College must be acknowledged. Find more information on our Engaged Learning and Research page.