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An In Vitro Pulsatile Culture System Allows For Quantification Of Vessel Dynamics Under Pulsatile, Steady, And Static Conditions

Oscar Abilez, Peyman Benharash, Chengpei Xu, Christopher Zarins ∙ Stanford University, Stanford, CA

Objective: Blood vessels undergo significant remodeling after endovascular manipulation such as angioplasty and stenting. Our long-term goal is to develop a pulsatile organ culture system to systematically apply combinations of biomechanical, biochemical, and pharmaceutical stimuli to study the remodeling of native, stented, and tissue-engineered blood vessels. As a first step to this goal, our objective was to quantify vessel wall motion under different flow conditions in order to relate biomechanical changes to vessel remodeling and gene expression. Methods: Aortas were harvested from male Sprague-Dawley rats. Two computer-controlled pumps provided pulsatile (50, 100, 150mmHg, 40mL/min, 54bpm) (Figure 1) or steady flow (30mmHg, 40mL/min) to the aortas, while control aortas were exposed to no flow. A video-microscopy system was used to track and analyze wall motion at 34 frames/second over 300 frames. The organ culture system provided computerized control of pH (7.4), temperature (37C), gas (5% CO2), and nutrient delivery over 8 hours. All vessels were subsequently fixed in paraformaldehyde and processed for further morphologic and gene expression analysis. Results: Wall motion under pulsatile flow at 50, 100, and 150mmHg was 594, 585, and 582μm, under steady flow was 83μm, and under static conditions was 14μm. Maximum vessel diameter for pulsatile, steady, and static flow was 2.9, 2.5, and 2.4μm, respectively. All vessels were viable after 8 hours of culture. Conclusions: Pulsatile flow at various pressures resulted in greater wall motion and maximum vessel diameter when compared to steady flow and static conditions. Ongoing analysis is aimed at how wall motion changes relate to morphologic and gene expression changes. Our system is a novel and robust in vitro platform that we will use to systematically test a wide array of factors and interventions on various native, stented, and tissue-engineered vessels.