Nakamachi Eiji, Uchida Takahiro, Kuramae Hiroyuki, Morita Yusuke
Department of Biomedical Engineering, Doshisha University, 1-3 Tatara-Miyakodani, Kyotanabe, Kyoto, 610-0394, Japan.
Int J Numer Method Biomed Eng. 2014 Aug;30(8):796-813. doi: 10.1002/cnm.2630. Epub 2014 Mar 5.
In this study, we developed a multi-scale finite element (FE) analysis code to obtain the stress and strain that occurred in the smooth muscle cell (SMC) at micro-scale, which was seeded in the real fabricated braid fibril artificial blood vessel. This FE code can predict the dynamic response of stress under the blood pressure loading. We try to establish a computer-aided engineering (CAE)-driven scaffold design technique for the blood vessel regeneration. Until now, there occurred the great progresses for the endothelial cell activation and intima layer regeneration in the blood vessel regeneration study. However, there remains the difficulty of the SMC activation and media layer regeneration. Therefore, many researchers are now studying to elucidate the fundamental mechanism of SMC activation and media layer regeneration by using the biomechanical technique. As the numerical tool, we used the dynamic-explicit FE code PAM-CRASH, ESI Ltd. For the material models, the nonlinear viscoelastic constitutive law was adapted for the human blood vessel, SMC and the extra-cellular matrix, and the elastic law for the polyglycolic acid (PGA) fiber. Through macro-FE and micro-FE analyses of fabricated braid fibril tubes by using PGA fiber under the combined conditions of the orientation angle and the pitch of fiber, we searched an appropriate structure for the stress stimulation for SMC functionalization. Objectives of this study are indicated as follows: 1. to analyze the stress and strain of the human blood vessel and SMC, and 2. to calculate stress and strain of the real fabricated braid fibril artificial blood vessel and SMC to search an appropriate PGA fiber structure under combined conditions of PGA fiber numbers, 12 and 24, and the helical orientation angles of fiber, 15, 30, 45, 60, and 75 degrees. Finally, we found a braid fibril tube, which has an angle of 15 degree and 12 PGA fibers, as a most appropriate artificial blood vessel for SMC functionalization.
在本研究中，我们开发了一种多尺度有限元（FE）分析代码，以获取微尺度下平滑肌细胞（SMC）内产生的应力和应变，该平滑肌细胞接种于实际制造的编织原纤维人工血管中。此有限元代码能够预测血压载荷下应力的动态响应。我们试图建立一种由计算机辅助工程（CAE）驱动的用于血管再生的支架设计技术。到目前为止，在血管再生研究中，内皮细胞激活和内膜层再生已取得了巨大进展。然而，SMC激活和中膜层再生仍然存在困难。因此，许多研究人员目前正在通过生物力学技术研究以阐明SMC激活和中膜层再生的基本机制。作为数值工具，我们使用了ESI有限公司的动态显式有限元代码PAM - CRASH。对于材料模型，人类血管、SMC和细胞外基质采用非线性粘弹性本构定律，聚乙醇酸（PGA）纤维采用弹性定律。通过在纤维取向角和螺距的组合条件下对使用PGA纤维制造的编织原纤维管进行宏观有限元和微观有限元分析，我们寻找一种适合SMC功能化应力刺激的合适结构。本研究的目标如下：1. 分析人类血管和SMC的应力与应变；2. 计算实际制造的编织原纤维人工血管和SMC的应力与应变，以在PGA纤维数量为12和24以及纤维螺旋取向角为15、30、45、60和75度的组合条件下寻找合适的PGA纤维结构。最后，我们发现一种角度为15度且有12根PGA纤维的编织原纤维管，是最适合SMC功能化的人工血管。
