Korossis Sotirios A, Wilcox Helen E, Watterson Kevin G, Kearney John N, Ingham Eileen, Fisher John
Institute of Medical and Biological Engineering, University of Leeds, Leeds, UK.
J Heart Valve Dis. 2005 May;14(3):408-21; discussion 422.
Tissue-engineered heart valves offer the potential to deliver a heart valve replacement that will develop with the young patient. The present authors' approach is to use decellularized aortic heart valves reseeded in vitro or in vivo with the patient's own cells. It has been reported that treatment of porcine aortic valve leaflets with 0.1% (w/v) sodium dodecyl sulfate (SDS) in hypotonic buffer produced complete leaflet acellularity without affecting tissue strength. The present study aim was to investigate the effect of an additional treatment incorporating 1.25% (w/v) trypsin and 0.1% (w/v) SDS on the biomechanics and hydrodynamics of the aortic root. This treatment has been shown to produce decellularization of both the aorta and valve leaflets.
Fresh porcine aortic roots were treated to reduce the thickness of their aortic wall, and incubated in hypotonic buffer for 24 h. The leaflets were masked with agarose gel, and the aorta was treated with 1.25% (w/v) trypsin for 4 h at 37 degrees C. The trypsin and agarose were removed and the roots incubated with 0.1% (w/v) SDS in hypotonic buffer for 24 h. Fresh and treated circumferential and axial aortic specimens were subjected to uniaxial tensile testing, while intact porcine aortic roots were subjected to dilation and pulsatile flow testing.
Decellularized aortic wall specimens demonstrated significantly decreased elastin phase slope and increased transition strain compared to the fresh control. However, the treatment did not impair tissue strength. Decellularized intact roots presented complete leaflet competence under systemic pressures, increased dilation and effective orifice areas, reduced pressure gradients, physiological leaflet kinematics and reduced leaflet deformation.
The excellent leaflet kinematics and hydrodynamic performance of the decellularized roots, coupled with the excellent biomechanical characteristics of their aortic wall, form a promising platform for the creation of an acellular valve scaffold with adequate mechanical strength and functionality to accommodate dynamic cell repopulation in vitro or in vivo. This approach can be used for both allogeneic and xenogeneic tissue matrices.
组织工程心脏瓣膜为年轻患者提供了一种能够随其生长发育的心脏瓣膜置换方案。本文作者的方法是使用经脱细胞处理的主动脉心脏瓣膜，在体外或体内重新接种患者自身的细胞。据报道，在低渗缓冲液中用0.1%（w/v）十二烷基硫酸钠（SDS）处理猪主动脉瓣叶可实现完全脱细胞，且不影响组织强度。本研究旨在探讨额外加入1.25%（w/v）胰蛋白酶和0.1%（w/v）SDS的处理对主动脉根部生物力学和流体动力学的影响。该处理已被证明可使主动脉和瓣叶均实现脱细胞。
对新鲜猪主动脉根部进行处理以减小其主动脉壁厚度，然后在低渗缓冲液中孵育24小时。用琼脂糖凝胶覆盖瓣叶，将主动脉在37℃下用1.25%（w/v）胰蛋白酶处理4小时。去除胰蛋白酶和琼脂糖，将根部在低渗缓冲液中用0.1%（w/v）SDS孵育24小时。对新鲜的和处理后的主动脉周向及轴向标本进行单轴拉伸试验，同时对完整的猪主动脉根部进行扩张和脉动流试验。
与新鲜对照相比，脱细胞主动脉壁标本的弹性蛋白相斜率显著降低，过渡应变增加。然而，该处理并未损害组织强度。脱细胞完整根部在体循环压力下呈现出完全的瓣叶功能，扩张和有效瓣口面积增加，压力梯度降低，瓣叶运动学符合生理状态且瓣叶变形减少。
脱细胞根部出色的瓣叶运动学和流体动力学性能，以及其主动脉壁优异的生物力学特性，构成了一个有前景的平台，可用于创建具有足够机械强度和功能的无细胞瓣膜支架，以适应体外或体内的动态细胞再植入。这种方法可用于同种异体和异种组织基质。
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