Logos Biosystems X-CLARITY Tissue Clearing System

Description:

It has long been a major challenge to acquire high-resolution image data from relatively large and complex biological samples (e.g., intact embryos, whole organs of animal models and thick tissue sections) to obtain a systems view of the biological question being studied. Most biological tissues are non-transparent; this is mainly attributed to the lipid bilayer that makes up the cellular membrane in each of the rather packed biological cells within the tissue. Light scattering at the lipid-water interphase (due to differences in refractive index) causes serious problems for imaging, making deep-tissue imaging extremely challenging (the penetration depths in such tissue using confocal and multi-photo imaging are only ~100 and ~500 µm, respectively). In 2013, an electrophoretic tissue clearing (ETC) technique, termed CLARITY, was introduced by Chung and colleagues (Nature 497, 332-337 (2013)) at Stanford University. Since then, they and numerous other research groups have shown how CLARITY could address most of these challenges using a wide variety of biological tissues.

In brief, the CLARITY technique involves the following steps:

• Infusion of hydrogel monomers to the tissue
• Polymerisation to construct a tissue-hydrogel hybrid construct
• Electrophoretic tissue clearing (ETC) to remove lipids in the sample, while keeping the biomolecules and fine structures largely intact

Following ETC, the tissue-hydrogel hybrid would become optically transparent and chemically accessible to deep-tissue antibody labelling and imaging. For example, an intact mouse brain (after ETC) could be immunolabelled and subsequently imaged with light sheet fluorescence microscopy (LSFM), multiphoton microscopy (MPM) or even single-photon confocal microscopy.

Specifications:

Polymerisation system:

• Compatible with common plastic multi-well plates and 50 mL conical tubes
• Simultaneous processing of multiple samples contained in two heat blocks (one for 6 × 50 mL conical tubes and the other for 1 plastic multi-well plate)
• User-adjustable temperature, vacuum strength and duration
• Rapid (i.e., ~3 hours for common biological tissues) and consistent polymerisation

Electrophoretic tissue clearing (ETC) system:

• Active and passive clearing modes
• User-adjustable voltage, current, temperature, duration and pump speed
• Constant current and constant voltage modes
• Platinum-plated electrodes
• Multiple sample holders for tissues with varying shapes and sizes
• Holder for 6 tissue slices (max. sample diameter 1.5 cm)
• Holder for 6 mouse brains (max. sample diameter 0.6 cm)
• Holder for 6 mouse brains (max. sample diameter 1.5 cm)
• Holder for 36 mouse brain slices (max. sample diameter 0.6 cm
• Holder for 36 mouse brain slices (max. sample diameter 1.5 cm)
• Short ETC duration for common biological tissues (e.g., ~6 hours for a whole mouse brain)

Location: Y729

Hourly rate: $24 (internal users); $48 (collaborators); $120 (external users)

Consumables: X-CLARITY Mounting Solution ($800; 25 mL; RI = 1.46 at 25 °C)

Staff-in-charge: Dr Michael Yuen

Training: please contact Dr Michael Yuen (email: michael.yf.yuen@polyu.edu.hk / Tel.: 3400 8788) for arrangement.