Detection of cerebral tauopathy in P301L mice using high-resolution large-field multifocal illumination fluorescence microscopy

Abstract

Current intravital microscopy techniques visualize tauopathy with high-resolution, but have a small field-of-view and depth-of-focus. Herein, we report a transcranial detection of tauopathy over the entire cortex of P301L tauopathy mice using large-field multifocal illumination (LMI) fluorescence microscopy technique and luminescent conjugated oligothiophenes. In vitro assays revealed that fluorescent ligand h-FTAA is optimal for in vivo tau imaging, which was confirmed by observing elevated probe retention in the cortex of P301L mice compared to non-transgenic littermates. Immunohistochemical staining further verified the specificity of h-FTAA to detect tauopathy in P301L mice. The new imaging platform can be leveraged in pre-clinical mechanistic studies of tau spreading and clearance as well as longitudinal monitoring of tau targeting therapeutics.

Non-invasive imaging of tau-targeted probe uptake by whole brain multi-spectral optoacoustic tomography

“…Sub-millimeter scale intravital microscopy enables the visualization of tau deposits, but is highly invasive and can only cover a very limited FOV 49 . We recently reported on large FOV fluorescence microscopy imaging of tau in P301L mice with 6 micron resolution, which however only provided a planar view 43 . As the spatial resolution of vMSOT is not altered by photon scattering but rather governed by ultrasound diffraction, it enables high-resolution mapping and quantification of endogenous tissue chromophores or spectrally distinctive exogenous probes at millimeter to centimeter scale depths 55,87,88 .…”

“…However, microPET has a limited spatial resolution (0.7-1.5 mm) relative to the small mouse brain (~10 mm 3 ), which hinders accurate detection of tau, especially in small subcortical brain regions 41 . Fluorescence tau imaging using PBB5 33,42 , luminescent oligothiophene conjugated probe (h-FTAA) 43 , BF-158 42 , Q-tau 4 44 , pTP-TFE 45 , BODIPY derivative 46,47 and fluorescent-labelled antibodies 48 has also been reported. However, fluorescence imaging only provides a planar view, limited depth and limited quantification capabilities.…”

“…promoter (pR5 line, C57B6.Dg background)26,43,86,91,92 , and wild-type littermate mice were used (18 months-old, P301L n = 10, wild-type n = 10, both genders). Of which, N = 7 from each group was used in initial testing and for different dosage (Fig.4).…”

Non-invasive imaging of tau-targeted probe uptake by whole brain multi-spectral optoacoustic tomography

“…Submillimeter scale intravital microscopy enables the visualization of tau deposits, but is highly invasive and can only cover a very limited FOV [49]. We recently reported on large FOV uorescence microscopy imaging of tau in P301L mice with 6 micron resolution, which however only provided a planar view [41].…”

“…However, microPET has a limited spatial resolution (0.7-1.5mm) relative to the small mouse brain, which hinders accurate detection of tau, especially in small subcortical brain regions [40]. Fluorescence tau imaging studies using PBB5, luminescent oligothiophene conjugated probes, BF-158, Q-tau 4, pTP-TFE, BODIPY derivative [36,[41][42][43][44][45][46] and uorescent-labelled antibodies [47] have been reported. However, uorescence imaging provides a planar view and limited detection depth.…”