Ogle Brenda M, Mooradian Daniel L
Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA.
J Biomech Eng. 2002 Dec;124(6):724-33. doi: 10.1115/1.1519278.
There is a current need for a small diameter vascular graft due to the limited supply of autogenous grafts and the failure of synthetic grafts due to thrombosis and/or intimal hyperplasia. The use of living cells and tissues to fabricate a small diameter graft (i.e., tissue engineered blood vessel, TEBV) could be useful given the endothelialization potential and biocompatibility benefits of such a graft. However, while sufficient strength has been attained in a TEBV, coordinate compliance has yet to be fine-tuned. In this study we investigate the effects of biological response modifiers, retinoic acid (RA) and ascorbic acid (AA) on TEBV biomechanics as a function of time and subsequently correlate observed RA/AA induced changes in TEBV mechanics with alterations in smooth muscle cell (SMC) biochemistry. TEBVs were constructed using a fibrillar type I collagen network populated by human aortic smooth muscle cells (AoSMC). Following construction this TEBV was treated with 0.3 mM AA and 0.1 mM RA (concentrations found to induce changes in VSMC phenotype). Ultimate tensile stress (UTS), rate of relaxation (RR) and elastic efficiency (EE) of RA/AA treated and untreated TEBVs were measured following 1, 7, 15, 30, 45, and 60 days of treatment. At corresponding time points, the effect of these treatments on collagen and elastin protein synthesis and mRNA expression was examined. RA/AA treated TEBV strength increased and stiffness decreased compared to controls as a function of time. Relative collagen synthesis in treated TEBVs exceeded control levels by nearly two-fold at 15 and 30 days of incubation. RA/AA treated collagen gene expression followed a similar trend. Relative elastin synthesis was also greater in treated TEBVs as compared to untreated TEBVs at 15 and 30 days of incubation and correspondingly elastin mRNA expression was significantly elevated at 15 days of incubation. These data provide evidence that RA/AA treated TEBVs exhibit mechanical properties which more closely mimic those of a native vessel than their untreated counterparts and that changes in extracellular matrix composition and matrix gene expression in the presence of RA/AA treatment may play an important role in the development of said mechanical properties.
由于自体移植物供应有限，以及合成移植物因血栓形成和/或内膜增生而失效，目前对小直径血管移植物有需求。鉴于此类移植物具有内皮化潜力和生物相容性优势，利用活细胞和组织制造小直径移植物（即组织工程血管，TEBV）可能会有所帮助。然而，虽然TEBV已具备足够的强度，但协调顺应性仍有待微调。在本研究中，我们研究了生物反应调节剂视黄酸（RA）和抗坏血酸（AA）对TEBV生物力学随时间的影响，并随后将观察到的RA/AA诱导的TEBV力学变化与平滑肌细胞（SMC）生物化学变化相关联。使用由人主动脉平滑肌细胞（AoSMC）填充的纤维状I型胶原网络构建TEBV。构建后，将该TEBV用0.3 mM AA和0.1 mM RA处理（发现这些浓度可诱导VSMC表型变化）。在处理1、7、15、30、45和60天后，测量经RA/AA处理和未处理的TEBV的极限拉伸应力（UTS）、松弛速率（RR）和弹性效率（EE）。在相应时间点，检查这些处理对胶原蛋白和弹性蛋白合成及mRNA表达的影响。与对照组相比，经RA/AA处理的TEBV强度随时间增加而刚度降低。在培养15天和30天时，处理后的TEBV中相对胶原蛋白合成比对照水平高出近两倍。经RA/AA处理的胶原蛋白基因表达遵循类似趋势。在培养15天和30天时，处理后的TEBV中相对弹性蛋白合成也比未处理的TEBV更大，相应地，在培养15天时弹性蛋白mRNA表达显著升高。这些数据提供了证据，表明经RA/AA处理的TEBV表现出的力学性能比未处理的更接近天然血管，并且在RA/AA处理下细胞外基质组成和基质基因表达的变化可能在所述力学性能的发展中起重要作用。
