Liu Janet, Cornelius Kurtis, Graham Mathew, Leonard Tremayne, Tipton Austin, Yorde Abram, Sucosky Philippe
Department of Mechanical and Materials Engineering, Wright State University, 257 Russ Engineering Center, Dayton, OH, 45435, USA.
Cardiovasc Eng Technol. 2019 Sep;10(3):531-542. doi: 10.1007/s13239-019-00426-1. Epub 2019 Jul 15.
The cardiovascular endothelium experiences pulsatile and multidirectional fluid wall shear stress (WSS). While the effects of non-physiologic WSS magnitude and pulsatility on cardiovascular function have been studied extensively, the impact of directional abnormalities remains unknown due to the challenge to replicate this characteristic in vitro. To address this gap, this study aimed at designing a bioreactor capable of subjecting cardiovascular tissue to time-varying WSS magnitude and directionality.
The device consisted of a modified cone-and-plate bioreactor. The cone rotation generates a fluid flow subjecting tissue to desired WSS magnitude, while WSS directionality is achieved by altering the alignment of the tissue relative to the flow at each instant of time. Computational fluid dynamics was used to verify the device ability to replicate the native WSS of the proximal aorta. Cone and tissue mount velocities were determined using an iterative optimization procedure.
Using conditions derived from cone-and-plate theory, the initial simulations yielded root-mean-square errors of 22.8 and 8.4% in WSS magnitude and angle, respectively, between the predicted and the target signals over one cycle, relative to the time-averaged target values. The conditions obtained after two optimization iterations reduced those errors to 3.5 and 0.5%, respectively, and generated 0.2% and 0.01% difference in time-averaged WSS magnitude and angle, respectively, relative to the target waveforms.
A bioreactor capable of generating simultaneously desired time-varying WSS magnitude and directionality was designed and validated computationally. The ability to subject tissue to in vivo-like WSS will provide new insights into cardiovascular mechanobiology and disease.
心血管内皮承受着搏动性和多向性的流体壁面剪应力（WSS）。虽然非生理性WSS大小和搏动性对心血管功能的影响已得到广泛研究，但由于在体外复制这种特性具有挑战性，方向性异常的影响仍不清楚。为了填补这一空白，本研究旨在设计一种生物反应器，能够使心血管组织承受随时间变化的WSS大小和方向性。
该装置由一个改良的锥板生物反应器组成。锥形体旋转产生流体流动，使组织承受所需的WSS大小，而WSS方向性则通过在每个时刻改变组织相对于流动的排列来实现。使用计算流体动力学来验证该装置复制近端主动脉天然WSS的能力。锥形体和组织固定速度通过迭代优化程序确定。
使用从锥板理论得出的条件，初始模拟在一个周期内预测信号与目标信号之间的WSS大小和角度的均方根误差分别为22.8%和8.4%，相对于时间平均目标值。经过两次优化迭代后获得的条件将这些误差分别降低到3.5%和0.5%，并且相对于目标波形，时间平均WSS大小和角度的差异分别为0.2%和0.01%。
设计了一种能够同时产生所需随时间变化的WSS大小和方向性的生物反应器，并通过计算进行了验证。使组织承受类似体内WSS的能力将为心血管力学生物学和疾病提供新的见解。
