BME Seminar Series: Faisal Fakhouri, Megan Heitkemper, & Bharat Kumar
"Lens Stretching Modulates Lens Epithelial Cell Proliferation"
The continuous growth of the lens throughout life may contribute to the onset of age-related conditions in the lens (i.e., presbyopia and cataract). Volumetric growth is the result of continuous proliferation of lens epithelial cells (LECs). This study tested the hypothesis that mechanical stretching modulates LEC proliferation by culturing whole porcine lenses and connective tissues ex vivo under varying physiologically relevant stretching conditions using a bespoke lens stretching device. Resulting changes in LEC labeling index were analyzed using EdU incorporation and flow cytometry for each lens. LEC proliferation was found to be modulated by mechanical strain. Increasing both the magnitude of static stretching and the stretching frequency in cyclic stretching resulted in a proportional increase in the labeling indices of the LECs. These data demonstrate that LEC proliferation is regulated in part, by the mechanotransduction of stresses induced in the lens capsule. These results have important implications for understanding lens growth and morphogenesis.
"Magnetic Resonance Elasography of The Lungs"
Lung diseases are one of the leading causes of death worldwide, from which four million people die annually. Lung diseases alter the structure of lung parenchyma from which its mechanical properties can change. Change in lung's mechanical properties can provide critical information regarding the functional properties of the lung. Several studies have shown the feasibility of using magnetic resonance elastography (MRE) to quantify the lungs' shear stiffness during a breathhold. So the aim of this PhD dissertation was to first confirm the repeatability and reproducibility of the MRE stiffness measurements with a breathhold on healthy volunteers. Since lung patients suffers from breathlessness, the second aim was to develop a free breathing MRE technique and investigate its repeatability and reproducibility on healthy volunteers. Finally, apply the newly developed free breathing technique on patients with lung diseases.
"Introduction of a Simple 2D Computational Model to Predict Risk of Coronary Obstruction During Transcatheter Aortic Valve Replacement"
Coronary artery obstruction is a rare, yet often fatal, complication that can occur during transcatheter aortic valve replacement (TAVR). While TAVR represents a major advancement for the treatment of patients with severe aortic stenosis, risk of complications such as coronary obstruction can determine candidacy and reduce the mortality and quality of life benefits ascribed to TAVR. While a serious and potentially preventable complication, there is no consensus to which features reliably predispose risk of coronary obstruction during TAVR. Most of the guidelines developed so far have originated from clinical trials designed to exclude as many adverse outcomes as possible, which can possibly exclude a large number of potential TAVR patients, often those who have no other treatment options available. In contrast, complex computational simulations have shown potential for greater accuracy, though computational time and complexity have limited practical use. In this retrospective study, a simple mechanistic index was developed that can predict which high risk patients are not actually at risk and are indeed candidates for TAVR pre-operatively, allowing for the most patients possible to safely undergo TAVR without coronary obstruction. An overarching objective of this study is to better understand the physical mechanism of coronary obstruction beyond the conventional parameters of coronary artery height and Sinus of Valsalva diameter alone.