CCL2/CCR2 轴对于招募巨噬细胞进入去细胞神经移植物桥接神经间隙以促进血管生成和再生至关重要。

The CCL2/CCR2 axis is critical to recruiting macrophages into acellular nerve allograft bridging a nerve gap to promote angiogenesis and regeneration.

机构信息

Division of Plastic and Reconstructive Surgery, Department of Surgery, Washington University School of Medicine, St. Louis, MO, 63110, USA.

Division of Plastic and Reconstructive Surgery, Department of Surgery, Washington University School of Medicine, St. Louis, MO, 63110, USA.

出版信息

Exp Neurol. 2020 Sep;331:113363. doi: 10.1016/j.expneurol.2020.113363. Epub 2020 May 23.

Abstract

Acellular nerve allografts (ANAs) are increasingly used to repair nerve gaps following injuries. However, these nerve scaffolds have yet to surpass the regenerative capabilities of cellular nerve autografts; improved understanding of their regenerative mechanisms could improve design. Due to their acellular nature, both angiogenesis and diverse cell recruitment is necessary to repopulate these scaffolds to promote functional regeneration. We determined the contribution of angiogenesis to initial cellular repopulation of ANAs used to repair nerve gaps, as well as the signaling that drives a significant portion of this angiogenesis. Wild-type (WT) mice with nerve gaps repaired using ANAs that were treated with an inhibitor of VEGF receptor signaling severely impaired angiogenesis within ANAs, as well as hampered cell repopulation and axon extension into ANAs. Similarly, systemic depletion of hematogenous-derived macrophages, but not neutrophils, in these mice models severely impeded angiogenesis and subsequent nerve regeneration across ANAs suggesting hematogenous-derived macrophages were major contributors to angiogenesis within ANAs. This finding was reinforced using CCR2 knockout (KO) models. As macrophages represented the majority of CCR2 expressing cells, a CCR2 deficiency impaired angiogenesis and subsequent nerve regeneration across ANAs. Furthermore, an essential role for CCL2 during nerve regeneration across ANAs was identified, as nerves repaired using ANAs had reduced angiogenesis and subsequent nerve regeneration in CCL2 KO vs WT mice. Our data demonstrate the CCL2/CCR2 axis is important for macrophage recruitment, which promotes angiogenesis, cell repopulation, and subsequent nerve regeneration and recovery across ANAs used to repair nerve gaps.

摘要

去细胞神经同种异体移植物(ANAs)越来越多地被用于修复损伤后的神经间隙。然而,这些神经支架尚未超过细胞神经自体移植物的再生能力;对其再生机制的更好理解可能会改进设计。由于其去细胞特性,需要血管生成和多种细胞募集来填充这些支架,以促进功能再生。我们确定了血管生成对用于修复神经间隙的 ANAs 初始细胞再殖的贡献,以及驱动这部分血管生成的信号。用 VEGF 受体信号抑制剂处理用于修复神经间隙的 ANAs 的 WT 小鼠中,神经间隙中的血管生成严重受损,细胞再殖和轴突延伸到 ANAs 中受到阻碍。同样,在这些小鼠模型中,全身性耗尽血液来源的巨噬细胞,但不是中性粒细胞,严重阻碍了血管生成和随后穿过 ANAs 的神经再生,表明血液来源的巨噬细胞是 ANAs 内血管生成的主要贡献者。使用 CCR2 敲除(KO)模型加强了这一发现。由于巨噬细胞代表了大多数表达 CCR2 的细胞,CCR2 缺乏会损害 ANAs 内的血管生成和随后的神经再生。此外,还确定了 CCL2 在 ANAs 穿过神经再生过程中的重要作用,因为在 CCL2 KO 与 WT 小鼠中,使用 ANAs 修复的神经血管生成减少,随后的神经再生也减少。我们的数据表明,CCL2/CCR2 轴对于巨噬细胞募集很重要,这促进了血管生成、细胞再殖以及随后穿过用于修复神经间隙的 ANAs 的神经再生和恢复。

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