Ichihashi Shigeo, Wolf Frederic, Schmitz-Rode Thomas, Kichikawa Kimihiko, Jockenhoevel Stefan, Mela Petra
Department of Tissue Engineering and Textile Implants, AME - Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstrasse 20, 52074, Aachen, Germany.
Department of Radiology, Nara Medical University, Nara, Japan.
Cardiovasc Intervent Radiol. 2017 Aug;40(8):1229-1236. doi: 10.1007/s00270-017-1661-x. Epub 2017 May 18.
Covered stents have been demonstrated to reduce restenosis; however, the membrane's limited biocompatibility can still lead to thrombus formation. To obtain optimal surface hemocompatibility, endothelialization of the luminal surface has been proposed. However, the effect of delivery procedures, such as crimping and balloon dilatation, on the endothelial layer has not been quantified. This study investigated the impact of such procedures on endothelialized covered stents in vitro.
Using an injection molding technique, bare metal stents were covered with fibrin subsequently, endothelialized and conditioned in a bioreactor under arterial pressure (80-120 mmHg) and shear stress (1 Pa). For each set of experiments, three covered stents were prepared, one being subjected to crimping alone, one to crimping followed by balloon dilatation and one serving as control. The experiment was repeated three times. The endothelial coverage was quantified by scanning electron microscopy (SEM). The functionality of the endothelium after exposure to platelet-rich plasma was evaluated by immunohistochemistry and SEM.
The mean endothelial coverage of control, crimped, crimped and balloon-dilated stents was 87.6, 80.1 and 52.1%, respectively, indicating that endothelial cells detached significantly not after crimping (P = 0.465) but following balloon dilatation (P < 0.001). The cells present on the stent's surface, either after crimping or crimping followed by balloon dilatation, expressed eNOS and CD31 and exhibited no platelet adhesion.
The simulated delivery procedure resulted in the retention of viable cells on more than half of the luminal surface. The main damage to the layer occurred during balloon dilatation.
覆膜支架已被证明可减少再狭窄；然而，膜的生物相容性有限仍可导致血栓形成。为获得最佳的表面血液相容性，有人提出使管腔表面内皮化。然而，诸如压握和球囊扩张等输送程序对内皮细胞层的影响尚未得到量化。本研究在体外研究了此类程序对内皮化覆膜支架的影响。
采用注射成型技术，随后用纤维蛋白覆盖裸金属支架，使其内皮化，并在生物反应器中于动脉压（80 - 120 mmHg）和剪切应力（1 Pa）条件下进行预处理。对于每组实验，制备三个覆膜支架，一个仅进行压握，一个先进行压握再进行球囊扩张，一个作为对照。实验重复三次。通过扫描电子显微镜（SEM）对内皮覆盖率进行量化。通过免疫组织化学和SEM评估暴露于富血小板血浆后内皮的功能。
对照、压握、压握后球囊扩张的支架的平均内皮覆盖率分别为87.6%、80.1%和52.1%，表明内皮细胞不是在压握后（P = 0.465）而是在球囊扩张后（P < 0.001）显著脱落。无论是在压握后还是压握后球囊扩张后，支架表面存在的细胞均表达eNOS和CD31，且未观察到血小板黏附。
模拟的输送程序使超过一半的管腔表面保留了存活细胞。该层的主要损伤发生在球囊扩张过程中。
