A Multifaceted Approach to Enhance the Current Understanding and Treatment of Calcific Aortic Valve Disease
Grande-Allen, K. Jane
Doctor of Philosophy
Calcific aortic valve disease (CAVD) is a serious condition with unclear mechanisms driving this disease. This research focused on investigating the role of lysophosphatidylcholine (LPC) in CAVD and evaluating the efficacy of Raman spectroscopy (RS) to aid in current tissue engineering methods of heart valve replacements used to treat CAVD. Appropriate culture conditions for in vitro studies of CAVD were established. Specifically, the application of gentamicin in valvular interstitial cell (VIC) cultures was determined to significantly decrease mineralization of VICs in vitro in both normal and pre-calcified VIC culture conditions. Next, in vitro studies were conducted examining the role of LPC in a comparison of aortic and mitral VIC mineralization. Results indicated a higher percentage of LPC in calcified regions of tissue compared to non-calcified regions. In addition, 10000 nM LPC led to an increase in VIC mineralization, and aortic VICs displayed greater mineralization compared to mitral VICs. The role of the ryanodine receptor (RyR) in LPC-induced mineralization was evaluated. The presence of RyR isoforms 2 and 3 were confirmed in VICs. Next, in the presence of 10 µM LPC, the RyR was blocked and mineralization in VIC cultures significantly decreased compared to LPC treated cultures in which the RyR was not blocked. Several strategies exist for utilizing mesenchymal stem cells (MSCs) for tissue engineering of heart valves (TEHV) for valve replacement therapies. In this research, RS was able to detect distinct molecular characteristics of MSCs from different sources. This research has a significant impact on the study and understanding of CAVD. It suggests that gentamicin be used cautiously with in vitro studies of calcification, and suggest that mechanisms by which gentamicin acts in VICs may reverse calcification. In addition, these results showed that LPC has the capacity to promote VIC calcification, by interacting with the RyR, and that aortic VICs have a greater propensity for mineralization compared to mitral VICs. Also, RS may be used in future research to characterize MSCs prior to their use in TEHV. This research has highlighted the need for future investigations of LPC and the use of RS in understanding and treating CAVD.