Martínez-Andrade Juan M, Salgado-Bautista Daniel, Ramirez-Acosta Kendra, Cadena-Nava Ruben Darío, Riquelme Meritxell
Department of Microbiology, Centro de Investigación Científica y Educación Superior de Ensenada (CICESE), Ensenada, Baja California, Mexico.
Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Ensenada, Baja California, Mexico.
Microbiol Spectr. 2025 Jul;13(7):e0302624. doi: 10.1128/spectrum.03026-24. Epub 2025 May 22.
Extracellular vesicles (EVs) have gained considerable attention in fungal biology research. However, imaging these membrane-bound particles presents challenges due to their nanoscopic size (typically <200 nm), which exceeds the resolution limit of conventional diffraction-limited laser scanning confocal microscopy (LSCM). While high-resolution techniques like transmission electron microscopy (TEM) offer superior spatial resolution, they are time-consuming, require specialized expertise, and are prone to artifacts that can interfere with accurate results. In this study, we propose a rapid method for confirming the vesicular nature of EVs using a correlative light and electron microscopy (CLEM) approach. EVs were isolated from culture filtrates of the model filamentous fungus and their membranes were stained with the fluorogenic styryl dye FM1-43 for analysis. Fluorescent microspheres were used as fiducial markers alongside the stained EVs during sample preparation. Samples were first examined using LSCM, followed by negative staining with OsO vapors or uranyl acetate. The same regions observed with LSCM were subsequently analyzed with TEM. CLEM analysis revealed that vesicle-like structures with membranous features, as observed under TEM, corresponded to the dispersed green fluorescence signal seen with LSCM. These findings validate CLEM as a reliable method to examine the presence of EVs. This method can be implemented easily in labs that do not have access to a core facility with sophisticated multimodal microscopes. Furthermore, this method can be extended to study other structures, such as secretory vesicles, viral particles, protein nanoparticles, and polymeric nanoparticles.IMPORTANCEThis study presents an efficient and cost-effective correlative light and electron microscopy workflow for imaging nanosized extracellular vesicles (EVs) and other biological samples. The methodology involves sequential imaging using laser scanning confocal microscopy (LSCM) followed by transmission electron microscopy (TEM), enabling comprehensive characterization of EVs. This protocol uses fluorescence microscopy dyes to stain EV membranes and OsO vapors for negative or positive staining in TEM. This approach provides a reliable, versatile tool for studying nanoscale biological structures, with broad applications in cellular biology, nanomedicine, and related research fields.
细胞外囊泡(EVs)在真菌生物学研究中受到了广泛关注。然而,对这些膜结合颗粒进行成像具有挑战性,因为它们的纳米级尺寸(通常<200 nm)超过了传统衍射极限激光扫描共聚焦显微镜(LSCM)的分辨率极限。虽然像透射电子显微镜(TEM)这样的高分辨率技术提供了卓越的空间分辨率,但它们耗时、需要专业知识,并且容易出现可能干扰准确结果的伪像。在本研究中,我们提出了一种使用相关光电子显微镜(CLEM)方法快速确认EVs囊泡性质的方法。从模式丝状真菌的培养滤液中分离出EVs,并用荧光苯乙烯染料FM1-43对其膜进行染色以进行分析。在样品制备过程中,荧光微球与染色的EVs一起用作基准标记。首先使用LSCM检查样品,然后用OsO蒸汽或醋酸铀进行负染色。随后用TEM分析在LSCM下观察到的相同区域。CLEM分析表明,在TEM下观察到的具有膜特征的囊泡状结构与LSCM下看到的分散绿色荧光信号相对应。这些发现验证了CLEM作为检测EVs存在的可靠方法。这种方法可以在没有配备复杂多模态显微镜的核心设施的实验室中轻松实施。此外,该方法可以扩展到研究其他结构,如分泌囊泡、病毒颗粒、蛋白质纳米颗粒和聚合物纳米颗粒。重要性本研究提出了一种高效且经济高效的相关光电子显微镜工作流程,用于对纳米级细胞外囊泡(EVs)和其他生物样品进行成像。该方法包括使用激光扫描共聚焦显微镜(LSCM)进行顺序成像,然后进行透射电子显微镜(TEM)成像,从而能够对EVs进行全面表征。该方案使用荧光显微镜染料对EV膜进行染色,并使用OsO蒸汽在TEM中进行负染色或正染色。这种方法为研究纳米级生物结构提供了一种可靠、通用的工具,在细胞生物学、纳米医学和相关研究领域具有广泛应用。
Arch Ital Urol Androl. 2025-6-30
Health Technol Assess. 2006-9
Cochrane Database Syst Rev. 2022-5-20
Cochrane Database Syst Rev. 2022-1-17
Cochrane Database Syst Rev. 2018-1-22
Cochrane Database Syst Rev. 2008-7-16
Cochrane Database Syst Rev. 2022-10-4
Cochrane Database Syst Rev. 2025-2-19
Methods Mol Biol. 2024
Microbes Infect. 2024
Fungal Genet Biol. 2023-3
Nat Commun. 2022-12-2
J Fungi (Basel). 2021-7-14