Basic Study
Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Cardiol. Jan 26, 2016; 8(1): 89-97
Published online Jan 26, 2016. doi: 10.4330/wjc.v8.i1.89
Bicuspid aortic valve hemodynamics does not promote remodeling in porcine aortic wall concavity
Samantha K Atkins, Alison N Moore, Philippe Sucosky
Samantha K Atkins, Alison N Moore, Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556, United States
Philippe Sucosky, Department of Mechanical and Materials Engineering, Wright State University, Dayton, OH 45435, United States
Author contributions: Atkins SK performed the experiments and biological assays, and conducted the analysis; Moore AN performed the biological assays; Atkins SK and Sucosky P wrote the paper.
Supported by National Science Foundation, Nos. CMMI-1148558 and CMMI-1550144.
Institutional review board statement: Not applicable (no human/animal subjects).
Institutional animal care and use committee statement: Not applicable (no human/animal subjects).
Conflict-of-interest statement: The authors declare no conflict of interest.
Data sharing statement: Complete dataset and statistical analyses available from the corresponding author at philippe.sucosky@wright.edu.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Philippe Sucosky, PhD, FAHA, Department of Mechanical and Materials Engineering, Wright State University, 257 Russ Engineering Center, 3640 Colonel Glenn Highway, Dayton, OH 45435, United States. philippe.sucosky@wright.edu
Telephone: +1-937-7754650 Fax: +1-937-7755082
Received: September 27, 2015
Peer-review started: October 3, 2015
First decision: October 27, 2015
Revised: October 30, 2015
Accepted: December 3, 2015
Article in press: December 4, 2015
Published online: January 26, 2016
Processing time: 121 Days and 15.8 Hours
Abstract

AIM: To investigate the role of type-I left-right bicuspid aortic valve (LR-BAV) hemodynamic stresses in the remodeling of the thoracic ascending aorta (AA) concavity, in the absence of underlying genetic or structural defects.

METHODS: Transient wall shear stress (WSS) profiles in the concavity of tricuspid aortic valve (TAV) and LR-BAV AAs were obtained computationally. Tissue specimens excised from the concavity of normal (non-dilated) porcine AAs were subjected for 48 h to those stress environments using a shear stress bioreactor. Tissue remodeling was characterized in terms of matrix metalloproteinase (MMP) expression and activity via immunostaining and gelatin zymography.

RESULTS: Immunostaining semi-quantification results indicated no significant difference in MMP-2 and MMP-9 expression between the tissue groups exposed to TAV and LR-BAV AA WSS (P = 0.80 and P = 0.19, respectively). Zymography densitometry revealed no difference in MMP-2 activity (total activity, active form and latent form) between the groups subjected to TAV AA and LR-BAV AA WSS (P = 0.08, P = 0.15 and P = 0.59, respectively).

CONCLUSION: The hemodynamic stress environment present in the concavity of type-I LR-BAV AA does not cause any significant change in proteolytic enzyme expression and activity as compared to that present in the TAV AA.

Keywords: Bicuspid aortic valve; Fluid shear stress; Aortopathy; Remodeling; Matrix metalloproteinases

Core tip: The bicuspid aortic valve with left-right cusp fusion (LR-BAV) generates a stress overload on the ascending aorta (AA) convexity, which promotes aortic medial degeneration and aortic dilation. While the wall concavity is generally spared from the disease, the protective role of the local hemodynamics has not been demonstrated. This study aimed at comparing matrix metalloproteinase biology in AA concavity tissue subjected to the local hemodynamic stresses generated by a tricuspid aortic valve (TAV) and a LR-BAV. The results suggest that the fluid stresses in the TAV AA and LR-BAV AA concavity result in similar MMP expressions and activities.