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Journal of Zhejiang University SCIENCE B
ISSN 1673-1581(Print), 1862-1783(Online), Monthly
2023 Vol.24 No.6 P.510-523
Nanosilver alleviates foreign body reaction and facilitates wound repair by regulating macrophage polarization
Abstract: Foreign body reactions induced by macrophages often cause delay or failure of wound healing in the application of tissue engineering scaffolds. This study explores the application of nanosilver (NAg) to reduce foreign body reactions during scaffold transplantation. An NAg hybrid collagen-chitosan scaffold (NAg-CCS) was prepared using the freeze-drying method. The NAg-CCS was implanted on the back of rats to evaluate the effects on foreign body reactions. Skin tissue samples were collected for histological and immunological evaluation at variable intervals. Miniature pigs were used to assess the effects of NAg on skin wound healing. The wounds were photographed, and tissue samples were collected for molecular biological analysis at different time points post-transplantation. NAg-CCS has a porous structure and the results showed that it could release NAg constantly for two weeks. The NAg-CCS group rarely developed a foreign body reaction, while the blank-CCS group showed granulomas or necrosis in the subcutaneous grafting experiment. Both matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of metalloproteinase-1 (TIMP-1) were reduced significantly in the NAg-CCS group. The NAg-CCS group had higher interleukin (IL)-10 and lower IL-6 than the blank CCS group. In the wound healing study, M1 macrophage activation and inflammatory-related proteins (inducible nitric oxide synthase (iNOS), IL-6, and interferon-γ (IFN-γ)) were inhibited by NAg. In contrast, M2 macrophage activation and proinflammatory proteins (arginase-1, major histocompatibility complex-II (MHC-II), and found in inflammatory zone-1 (FIZZ-1)) were promoted, and this was responsible for suppressing the foreign body responses and accelerating wound healing. In conclusion, dermal scaffolds containing NAg suppressed the foreign body reaction by regulating macrophages and the expression of inflammatory cytokines, thereby promoting wound healing.
Key words: Nanosilver; Macrophages; Implants; Foreign body reaction; Wound repair
机构：1西北工业大学,航空学院，中国西安，710072；2翼型、叶栅空气动力学国家重点实验室，中国西安，710072；3中国空气动力研究与发展中心，结冰与防除冰重点实验室，中国绵阳，621000；4加泰罗尼亚理工大学，流体力学系，西班牙巴塞罗那，08034；5加泰罗尼亚理工大学，航空航天工程部，物理系，西班牙巴塞罗那，08034
目的：探究双边驱动方腔内流流场的过渡流临界特性，捕捉各种流动分岔点，分析其对流场特性带来的改变。确定流场演化模式，解释流动现象后的流动机理。通过流场拓扑结构和涡系演化分析流场稳定性与对称性的关系。
创新点：1.首次揭示驱动速度比对该流场过渡流临界特性的影响规律；2.从物理层面上阐明流动本质。
方法：1.以均匀直角网格构建计算域，通过基于格子玻尔兹曼方法的数值模拟方法，计算各流动状态发生变化时的临界雷诺数。根据不同驱动速度比，绘制Hopf和Neimark-Sacker流动分岔点以及湍流临界点随速度比的函数图像（图9）；2.通过扰动衰减系数、速度相图、速度频谱分析来判断流动是否由定常变为非定常周期性流动，再由周期性流动变为准周期性流动直至演化为湍流；3.通过流场拓扑结构分析流场对称性的破坏与不稳定性的关系；4.通过能量频谱图像分析流动的能量级串现象（图11）。
结论：1.跟预期一样，该流场的稳定性丧失总是伴随着Hopf流动分岔点的出现；2.相较于顶盖驱动内流流场，双边驱动内流流场的稳定性较强，说明第二条边的驱动条件可以有效提高流场的稳定性；3.当时，流场稳定性最强，同时当双边驱动条件相同时可以更好的提高流场稳定性；4.不管驱动速度比如何变，流场始终展现了经典的Ruelle-Takens模式，从定常流动演化至非定常周期性流动，再由周期性流动演化至准周期性流动，最终演化为湍流；5.180度的旋转对称性对于推迟湍流的出现有很大作用。
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DOI:
10.1631/jzus.B2200447
CLC number:
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On-line Access:
2023-06-13
Received:
2022-09-08
Revision Accepted:
2023-01-27
Crosschecked:
2023-07-21