College of Bioengineering, Henan University of Technology, Lianhua Street, Zhengzhou 450001, China.
Laboratory of Microvascular Medicine, Medical Research Center, the First Affiliated Hospital of Shandong First Medical University, Jinan 250014, China.
ACS Nano. 2021 Jun 22;15(6):10640-10658. doi: 10.1021/acsnano.1c03456. Epub 2021 Jun 3.
Surface-modified mesoporous silica nanoparticles (MSNs) have attracted more and more attention as promising materials for biomolecule delivery. However, the lack of detailed evaluation relevant to the potential cytotoxicity of these MSNs is still a major obstacle for their applications. Unlike the bare MSNs and amino- or liposome-modified MSNs, we found that polyethylenimine-modified MSNs (MSNs-PEI) had no obvious toxicity to human umbilical vein endothelial cells (HUVECs) at the concentrations up to 100 μg/mL. However, MSNs-PEI induced autophagosomes accumulation by blocking their fusion with lysosomes, an essential mechanism for the cytotoxicity of many nanoparticles (NPs). Thus, we predicted that an alternative pathway for autophagosome clearance exists in HUVECs to relieve autophagic stress induced by MSNs-PEI. We found that MSNs-PEI prevented STX17 loading onto autophagosomes instead of influencing lysosomal pH or proteolytic activity. MSNs-PEI induced the structural alternation of the cytoskeleton but did not cause endoplasmic reticulum stress. The accumulated autophagosomes were released to the extracellular space microvesicles (MVs) when the autophagic degradation was blocked by MSNs-PEI. More importantly, blockade of either autophagosome formation or release caused the accumulation of damaged mitochondria and excessive ROS production in the MSNs-PEI-treated HUVECs, which in turn led to cell death. Thus, we propose here that the MV-mediated autophagosome release, a compensation mechanism, allows the vascular endothelial cell survival when the degradation of autophagosomes is blocked by MSNs-PEI. Accordingly, promoting the release of accumulated autophagosomes may be a protective strategy against the endothelial toxicity of NPs.
表面修饰的介孔硅纳米颗粒（MSNs）作为生物分子递送的有前途的材料引起了越来越多的关注。然而，缺乏对这些 MSNs 潜在细胞毒性的详细评估仍然是它们应用的主要障碍。与裸 MSNs 和氨基或脂质体修饰的 MSNs 不同，我们发现聚乙二烯亚胺修饰的 MSNs（MSNs-PEI）在高达 100μg/mL 的浓度下对人脐静脉内皮细胞（HUVECs）没有明显的毒性。然而，MSNs-PEI 通过阻断自噬体与溶酶体融合来诱导自噬体积累，这是许多纳米颗粒（NPs）细胞毒性的一个重要机制。因此，我们预测 HUVECs 中存在自噬体清除的替代途径，以缓解 MSNs-PEI 诱导的自噬应激。我们发现 MSNs-PEI 阻止 STX17 加载到自噬体上，而不是影响溶酶体 pH 或蛋白水解活性。MSNs-PEI 诱导细胞骨架的结构改变，但不会引起内质网应激。当自噬降解被 MSNs-PEI 阻断时，积累的自噬体被释放到细胞外空间的微泡（MVs）中。更重要的是，当自噬体形成或释放被阻断时，受损的线粒体在 MSNs-PEI 处理的 HUVECs 中积累，并产生过多的 ROS，这反过来导致细胞死亡。因此，我们在这里提出，MV 介导的自噬体释放是一种补偿机制，当自噬体的降解被 MSNs-PEI 阻断时，允许血管内皮细胞存活。因此，促进积累的自噬体的释放可能是一种针对 NPs 内皮毒性的保护策略。
