A new methodology for muscle phenotyping by Raman spectroscopy

Muscle fiber types perform distinct functions in skeletal muscle tissue, allowing a wide range of physical and motor capabilities. The characterization of these fibers is essential in several research fields, however, the methodologies currently used are quite expensive and time-consuming. Here we successfully demonstrate that Raman spectroscopy, combined with chemometric methods such as PCA, can distinguish different types of skeletal muscle fibers in the soleus muscle. Distinct spectral variations associated with tryptophan, phenylalanine, tyrosine, and the Amide I band were identified as critical biomarkers to differentiate fiber types. In addition, we highlight the structural changes of protein-related bands, demonstrating transitions and providing experimental evidence for conformational changes linked to muscle function. Our new methodology for detecting spectral patterns offers valuable insights into the biochemistry of muscle cells, enabling the identification of specific types of skeletal muscle fibers and paving the way for further investigations into these cells under various conditions, such as atrophy, hypertrophy, and sarcopenia.