Nichol Jason W, Petko Matus, Myung Richard J, Gaynor J William, Gooch Keith J
Department of Bioengineering, Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Ann Biomed Eng. 2005 Jun;33(6):721-32. doi: 10.1007/s10439-005-4494-8.
We previously demonstrated that growth and remodeling was stimulated in arteries elongated ex vivo using step increases in axial strain. Viability and vasoactivity were similar to fresh arteries, however there was a substantial decrease in the ultimate circumferential stress. To test the hypothesis that the subphysiological perfusion conditions (i.e., low pressure and flow) previously used caused the reduction, arteries were subjected to the identical elongation protocol (50% increase over 9 days) while being perfused with physiological levels of flow, viscosity and pulsatile pressure. A significant increase in unloaded length was achieved by elongation under both perfusion conditions, although the increase was less under physiological (7 +/- 1%) than under subphysiological conditions (19 +/- 2%, p < 0.005). When length at physiological stress was estimated using mechanical testing data the values were similar. The ultimate circumferential stress of arteries elongated under physiological conditions was increased (33%), whereas the ultimate axial stress was decreased (50%) as compared with arteries elongated under subphysiological conditions. Elongated arteries under both perfusion conditions showed significant increases in proliferation and collagen mass, and similar viability and appearance to fresh arteries. These data suggest that there is substantial cross-talk between perfusion conditions and axial strain that modulates arterial remodeling and length.
我们之前证明，使用轴向应变的逐步增加对离体延长的动脉进行刺激，可促进其生长和重塑。其活力和血管活性与新鲜动脉相似，然而，其极限周向应力大幅降低。为了验证之前使用的亚生理灌注条件（即低压和低流量）导致这种降低的假设，在灌注生理水平的流量、粘度和脉动压力的同时，对动脉进行相同的延长方案（9天内增加50%）。在两种灌注条件下，通过延长均实现了无负荷长度的显著增加，尽管生理条件下的增加（7±1%）低于亚生理条件下的增加（19±2%，p<0.005）。当使用力学测试数据估计生理应力下的长度时，这些值相似。与在亚生理条件下延长的动脉相比，在生理条件下延长的动脉的极限周向应力增加（33%），而极限轴向应力降低（50%）。在两种灌注条件下延长的动脉均显示增殖和胶原质量显著增加，且活力和外观与新鲜动脉相似。这些数据表明，灌注条件和轴向应变之间存在大量相互作用，可调节动脉重塑和长度。
