Raman spectroscopic investigation on the biomedical evolution of spinal cord injury and the therapeutic outcomes of its low-level laser therapy

Abstract

The mechanism of low-level laser therapy (LLLT) of spinal cord injury (SCI) is currently unclear, and clinical application of LLLT treatments lack standardized protocols, since the treatment outcomes depends on various light parameters such as wavelength, fluence intensity, polarization and irradiation duration. In this work, Raman spectroscopy, was adopted to investigate the pathological process of SCI and monitor SCI-LLLT treatment so that accurate guidance on the appropriate selection of irradiation parameters may be achieved by an nonlabelled and nondesctructive intraoperative molecular diagnosis method. In vitro Raman spectroscopy combined with multivariate analysis technology was adopted to investigate the biochemical variations in spinal cord tissue during the progression of SCI and LLLT treatment. Besides, a discriminant model based on the principal component analysis-linear discriminant analysis algorithm (PCA-LDA) was established to distinguish the spectra of spinal tissue at pathological stages. The results of spectral analysis indicated that a series of biochemical events had occurred following SCI, such as chondroitin sulfate proteoglycan (CSPG) aggregation, vascular rupture, demyelination, and cell necrosis. It also demonstrated that LLLT could promote tissue recovery after injury by inhibition of CSPG expression and an increase in the concentration of myelin in tissues. In addition, the discriminant model achieved an accuracy of 96.25 % and 98.13 % for the SCI and SCI-LLLT groups, respectively, which could be used for predicting LLLT treatment outcomes during clinical applications. The study provides support for the development of intraoperative real-time in vivo Raman diagnostic methods to monitor the course of SCI-LLLT, allowing the selection of appropriate laser parameters and therapeutic strategies for clinical treatments.