ABSTRACT
Objective To study the stress on elastic substrate of an in vitro endothelial cell dynamic culture device, whose hemodynamic environment is designed to simulate the human body, and to test and observe the shear stress changes in elastic substrate of parallel plate flow chamber under different tensile stresses. Methods A series of static tensile tests were adopted to fit the condition of dynamic stretching. Namely, the silicone sheet with 2 different thicknesses were put into the device, and then applied with static stretch at the interval of 10% tensile rate (0%, 10%, 20%, 30%), and under the condition of maintaining its tensile rate, the chamber height after the stretch of silicon sheet was calculated. Based on the calculation of shear stress, shear stress curves at different tensile rates were obtained, to make comparative analysis on variation of the shear stress with the thickness of silicon sheet. Results The experimental result was consistent with the theoretical analysis. When the tensile rate was 30%, silicon sheet with 0.5 mm thickness would produce certain influence on shear stress of parallel plate flow chamber along with the change of tensile rate (the height of chamber), and the average and maximum shear stress were reduced by 10.1% and 10.4%, respectively. Conclusions The influence factors caused by the change of elastic substrate thickness after the introduction of tensile stress must be taken into account for the calculation of shear stress in parallel plate flow chamber. The result can provide experimental technology for the culture of endothelial cells in vitro and the design and development of novel parallel plate flow chamber.
ABSTRACT
BACKGROUND:After years of development, various in vitro loading devices for vascular tension stress have been created both at home and abroad, mainly including rectangular base stretching method, circular base deformation method and four-point bending beam load method. Although the circular base deformation method can wel reflect the real situations in vivo such as the expansion of the alveoli and vascular pulsation, the strain on the membrane is actinomorphic. The four-point bending beam load method can just bring limited strain range and load time, along with a difficult strain regulation. OBJECTIVE: To develop anin vitro loading device for vascular tension stress using the rectangular base stretching method. METHODS:Thisin vitro loading device for vascular tension stress developed according to mechatronics design consisted of power supply module, control module, drive module and data acquisition module. The device could achieve the tensile control on silicon diaphragm by high-precision control of the motor rotation angle and rotational speed. RESULTS AND CONCLUSION: Through tests and experiments, the device could meet the required range of parameters and simulatein vitro human tensile stress environment, which is preliminarily considered to develop successfuly, achieving that: (1) two work patterns: stress mode and strain mode so as to solve the standardization of silicone substrate as loading device; (2) tensile stress can be adjusted in a range of 0-5×105 Pa; (3) tensile strain can be adjusted in 0-40% range; (4) stretching frequency can be in the regulation of 0-80 times/min and the stretching time can be controled.
ABSTRACT
BACKGROUND:It is difficult to make an exact conclusion about the correlation between atherosclerosis and hemodynamic wal shear stress because of the complexity of the hemodynamic environment in the field of atherosclerosis research. OBJECTIVE:To analyze the relationship between characteristics of mural coronary artery hemodynamics parameters and atherosclerosis through myocardial bridge-coronary artery analog device. METHODS:Myocardial bridge-coronary artery analog device was used to simulate experiments in vitro. In the condition of keeping any related parameters unchanged, such as system temperature, the average flow rate and heart rate, we observed and recorded the changes of proximal and distal mean value and oscil atory value of shear stress of mural coronary artery by regulating the oppression level of myocardial bridge to mural coronary artery. RESULTS AND CONCLUSION:Under 0%oppression, there was no significant difference in distal and proximal mean value and oscil atory value of shear stress of mural coronary artery. Under 50%oppression, the proximal oscil atory value of shear stress was significantly larger than that in the distal end. Under 80%oppression, mean shear stress in the distal end was larger than that in the proximal end. Oscil atory value of shear stress in the proximal end was larger than that in the distal end. With increased oppression, the mean shear stress in the distal end was higher than that in the proximal end, but oscil atory value in the proximal end was higher than that in the distal end. These results indicated that the increase of the oscil atory value of the proximal shear stress of mural coronary artery is an important factor for the occurrence of atherosclerosis.