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Raman spectroscopy shows promise as a biomarker for complex nerve and muscle (neuromuscular) diseases. To maximise its potential, several challenges remain. These include the sensitivity to different instrument configurations, translation across preclinical/human tissues and the development of multivariate analytics that can derive interpretable spectral outputs for disease identification. Nonnegative matrix factorisation (NMF) can extract features from high‐dimensional data sets and the nonnegative constraint results in physically realistic outputs. In this study, we have undertaken NMF on Raman spectra of muscle obtained from different clinical and preclinical settings. First, we obtained and combined Raman spectra from human patients with mitochondrial disease and healthy volunteers, using both a commercial microscope and in‐house fibre optic probe. NMF was applied across all data, and spectral patterns common to both equipment configurations were identified. Linear discriminant models utilising these patterns were able to accurately classify disease states (accuracy 70.2–84.5%). Next, we applied NMF to spectra obtained from the mdx mouse model of a Duchenne muscular dystrophy and patients with dystrophic muscle conditions. Spectral fingerprints common to mouse/human were obtained and able to accurately identify disease (accuracy 79.5–98.8%). We conclude that NMF can be used to analyse Raman data across different equipment configurations and the preclinical/clinical divide. Thus, the application of NMF decomposition methods could enhance the potential of Raman spectroscopy for the study of fatal neuromuscular diseases. [ABSTRACT FROM AUTHOR]

Muscle biopsy remains an important component of the diagnostic repertoire for patients with suspected mitochondrial disease, underpinning specialist histopathological and biochemical analyses. Raman spectroscopy has not yet been applied to mitochondrial disease, and new fibre optic systems, with advantages in terms of cost and portability, could provide a rapid means to identify muscle pathology. In this study, we aimed to explore the potential of two different formats of Raman spectroscopy to identify mitochondrial disease: a miniaturised fibre optic Raman system and a standard commercial Raman microscope. Raman spectra were recorded from muscle samples from healthy volunteers (n = 10) and patients with genetically confirmed mitochondrial disease (n = 15). Multivariate classification algorithms demonstrated a high level of disease classification performance with both the fibre optic probe system and microscope (area under receiver operating characteristic curves 0.80–0.82). Key spectral changes associated with mitochondrial disease concerned the α‐helical configuration of proteins. The results suggest that Raman spectroscopy of muscle is worthy of further investigation as a technique for the rapid identification of mitochondrial disease. [ABSTRACT FROM AUTHOR]