Younis Julia, Ahn Taeyong, Tovias Luis, Ishola Azeez O, Leynes Carolina, Kirk Jason M, Perry Sienna K, Gandhi Akash, Emrick Joshua J, Lee Brendan H, Wythe Joshua D, Haelterman Nele A
Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA 77030.
Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA, USA 22903.
bioRxiv. 2025 Aug 18:2025.08.13.670136. doi: 10.1101/2025.08.13.670136.
Wholemount, 3-dimensional (3D) tissue imaging holds significant promise for analyzing heterogeneous musculoskeletal tissues, such as knee joints, that demand time- and labor-intensive processing using traditional histological methods. Current musculoskeletal clearing protocols rely on either solvent-based tissue clearing, which substantially alters the size and architecture of cleared tissues, possibly compromising downstream quantification and perhaps more importantly reducing signal from endogenous fluorescent reporters, or on expensive and time-consuming hydrogel-based approaches that requires specialized equipment. While aqueous-based clearing overcomes these challenges, there is a clear need for a method that is optimized for clearing musculoskeletal tissues and that can easily be implemented in a standard lab environment. Here, we present KneEZ Clear, a simple, rapid, and flexible aqueous-based method that renders mineralized and non-mineralized tissues of murine knee joints optically transparent. We show that KneEZ Clear, which is based on the EZ Clear method, is highly flexible, demonstrating efficacy in a wide range of murine musculoskeletal tissues including the vertebral column, hindlimb, skull, and teeth. Critically, KneEZ Clear does not require specialized equipment and retains endogenous signal from fluorophores and fluorescent proteins. Additionally, following clearing and wholemount imaging, precious samples can still be processed for subsequent 2D histological analyses for validation or further study. Finally, we show that KneEZ Clear can be applied to samples of disease models to reveal alterations in tissue architecture and homeostasis. The simplicity, versatility, and efficiency of KneEZ Clear for optical clearing of musculoskeletal tissues will accelerate our understanding of cellular interactions and dynamics in homeostasis and disease.
整体三维(3D)组织成像对于分析异质性肌肉骨骼组织(如膝关节)具有重要前景,而使用传统组织学方法分析这些组织需要耗费大量时间和人力。当前的肌肉骨骼组织透明化方案要么依赖基于溶剂的组织透明化方法,这种方法会显著改变透明化组织的大小和结构,可能会影响下游的定量分析,更重要的是可能会降低内源性荧光报告分子的信号;要么依赖昂贵且耗时的基于水凝胶的方法,这种方法需要专门的设备。虽然基于水相的透明化方法克服了这些挑战,但显然需要一种针对肌肉骨骼组织透明化进行优化且能在标准实验室环境中轻松实施的方法。在此,我们介绍KneEZ Clear,这是一种简单、快速且灵活的基于水相的方法,它能使小鼠膝关节的矿化和非矿化组织实现光学透明。我们表明,基于EZ Clear方法的KneEZ Clear具有高度的灵活性,在包括脊柱、后肢、头骨和牙齿在内的多种小鼠肌肉骨骼组织中都显示出有效性。至关重要的是,KneEZ Clear不需要专门的设备,并且能保留来自荧光团和荧光蛋白的内源性信号。此外,在透明化和整体成像之后,珍贵的样本仍可进行后续的二维组织学分析以进行验证或进一步研究。最后,我们表明KneEZ Clear可应用于疾病模型的样本,以揭示组织结构和内环境稳态的改变。KneEZ Clear在肌肉骨骼组织光学透明化方面的简单性、多功能性和效率将加速我们对稳态和疾病中细胞相互作用及动态变化的理解。