Fourier transform Raman spectroscopy analysis of spinal cord lesions treated with Photobiomodulation

Spinal cord injury (SCI) triggers a devastating secondary cascade of neuroinflammation and metabolic failure that extends functional deficits well beyond the initial impact site. Mitigating this progressive degeneration remains a critical challenge in regenerative medicine. This study investigated the neuroprotective efficacy of a 14-day 808-nm infrared photobiomodulation (PBM) regimen in a rat spinal cord contusion model. To objectively characterize microenvironmental molecular dynamics, Fourier-transform Raman (FT-Raman) spectroscopy was coupled with Principal Component Analysis (PCA) and validated via Hematoxylin and Eosin (H&E) and Luxol Fast Blue (LFB) histology. The results demonstrated that PBM effectively stabilizes the biochemical microenvironment 1 cm cranial to the lesion epicenter. Spectroscopic profiling is consistent with the finding that PBM preserves protein structural integrity (Amide I, 1660 cm^-1) and mitigates lipid disorder associated with myelin sheath degradation (2929-2859 cm^-1). Furthermore, PBM normalized glucose-related vibrational signatures (1123 cm^-1), thereby reducing the accumulation of unmetabolized substrates and suggesting improved tissue homeostasis. Moreover, spatial analysis revealed a differential therapeutic response: the cranial segment showed significant tissue sparing, whereas the distal segment exhibited higher resistance to treatment. Together, these findings indicate the potential of PBM as a targeted, non-invasive strategy to limit SCI propagation while highlighting FT-Raman spectroscopy as an effective, label-free platform for monitoring molecular neural repair.