Side Specific Flow Patterns in Normal Aortic Valve

Graduate #113
Discipline: Technology and Engineering
Subcategory: Biomedical Engineering

Sana Nasim - Florida International University
Co-Author(s): Glenda Castellanos, Denise Medina, and Sharan Ramaswamy, Florida International University, Miami, FL Lilliam Valdes-Cruz, Steven Bibevski, and Frank Scholl, Joe DiMaggio’s Children’s Hospital, Hollywood, FL

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Aortic heart valve (AHV) opens and closes approximately 3 billion times in a person’s lifetime, making it a mechanically robust environment in the body. AHV leaflets comprises of two valvular endothelial cells (VECs) layer. Ventricularis layer facing the left ventricle are exposed to pulsatile high shear laminar flow, whereas fibrosa layer facing the aorta is exposed to low oscillatory shear stresses. The mechanical signals are fluid-induced and at the cellular level are tied to the blood shear stress patterns that occur on the surface of the valve leaflets. It is of interest to investigate the biological pathways that can regulate the mechanical properties of VECs and define how changes to VEC cytoskeletal structures influences mechano-sensitive signal transduction pathways. Clinically derived echocardiograph data have been obtained from neonates. Computational fluid dynamics simulations were run on the clinical velocity profiles to achieve shear stress profiles. Next, the respective shear stress waveforms on isolated VECs from either side of porcine AHV were applied experimentally using shear stress cell assay system, Bioflux. It permits flow conditioning of cell monolayer in pre coated microfluidic channels. We determine that the resulting shear stress causes unique alteration in structural changes and gene expression with respect to side specifics. This observation provides the first step needed to understand the role of fluid-induced external mechanical environments on VECs. Future work will be to understand the shear stresses, structural changes and gene expression alteration under pathological condition.

Funder Acknowledgement(s): NSF FGLSAMP FIU Bridge to the Doctorate award HRD #1301998

Faculty Advisor: Sharan Ramaswamy, sramaswa@fiu.edu

Role: Benchtop shear stresses experiments (bioflux), structural changes analysis and gene expression analysis.