Monitoring peripheral nerve degeneration in ALS by label-free stimulated Raman scattering imaging.

Feng Tian,Minbiao Ji,Leonard Petrucelli,Wenlong Yang,X Sunney Xie,Naoki Suzuki,Yue Liu,Satomi Suzuki-Uematsu,Kevin Eggan,Aarti Sharma,Jeannie Chew,Daniel A Mordes,Rosanna Zhang,Joanie Mok,Neil A Shneider,Steve S.w Han ,Ester Leno-Durán ,Jack L Strominger ,Jin Yuan Wang ,Johnny Salameh ,Fa Ke Lu

doi:10.1038/ncomms13283

Abstract

The study of amyotrophic lateral sclerosis (ALS) and potential interventions would be facilitated if motor axon degeneration could be more readily visualized. Here we demonstrate that stimulated Raman scattering (SRS) microscopy could be used to sensitively monitor peripheral nerve degeneration in ALS mouse models and ALS autopsy materials. Three-dimensional imaging of pre-symptomatic SOD1 mouse models and data processing by a correlation-based algorithm revealed that significant degeneration of peripheral nerves could be detected coincidentally with the earliest detectable signs of muscle denervation and preceded physiologically measurable motor function decline. We also found that peripheral degeneration was an early event in FUS as well as C9ORF72 repeat expansion models of ALS, and that serial imaging allowed long-term observation of disease progression and drug effects in living animals. Our study demonstrates that SRS imaging is a sensitive and quantitative means of measuring disease progression, greatly facilitating future studies of disease mechanisms and candidate therapeutics.

Highlights

Here we show that stimulated Raman scattering (SRS) imaging can used to visualize peripheral nerve degeneration in amyotrophic lateral sclerosis (ALS) mouse models and post mortem materials
SRS imaging identified lipid ovoids in some SOD1G93A mice that showed no active denervation by EMG, suggesting that SRS alone or in combination with EMG may allow for the earliest in vivo detection of peripheral nervous degeneration in mouse models yet reported (Fig. 8e)[2,3,36,38,46,47,48,49,50,51,52,53,54,55]
In a study of minocycline, we found that SRS imaging enabled detection of the slowing of peripheral nerve degeneration induced by this compound

Summary

Introduction

We demonstrate that stimulated Raman scattering (SRS) microscopy could be used to sensitively monitor peripheral nerve degeneration in ALS mouse models and ALS autopsy materials. Our study demonstrates that SRS imaging is a sensitive and quantitative means of measuring disease progression, greatly facilitating future studies of disease mechanisms and candidate therapeutics. End point analyses currently used to monitor disease progression in mouse models are either laborious histological measurements or behavioural assays that can be impacted by operator-specific variance. Unbiased imaging methods could provide more precise measures of disease onset and progression, as well as reduce the length and ambiguity currently inherent to trials of candidate interventions in these models. There is growing interest in the importance of demyelination in ALS, systematic studies of peripheral nerve degeneration have not yet been carried out with SRS27

Methods

Results

Conclusion