Evaluating the anti-neuropathic effects of the thymol-loaded nanofibrous scaffold in a rat model of spinal cord injury

Roshanak Amirian ^1,2,3 Pardis Mohammadi Pour ⁴ Hassan Maleki ¹ Sajad Fakhri ¹ Sedigheh Asgary ⁵ Mohammad Hosein Farzaei ^1* Javier Echeverria ^6*

• ¹ Pharmaceutical Sciences Research Center, Health Institute, Kermanshah University of Medical Sciences, Kermanshah, Kerman, Iran
• ² Student Research Committee, Kermanshah University of Medical Sciences, Kermanshah, Kerman, Iran
• ³ USERN Office, Kermanshah University of Medical Sciences, Kermanshah, Iran
• ⁴ Department of Pharmacognosy, School of Pharmacy and Pharmaceutical Sciences, Isfahan University of Medical Sciences, Isfahan, Isfahan, Iran
• ⁵ Isfahan Cardiovascular Research Center, Applied Physiology Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
• ⁶ Departamento de Ciencias del Ambiente, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Santiago Metropolitan Region (RM), Chile

Background: Spinal cord injury (SCI) is a debilitating condition characterized by partial or complete loss of motor and sensory function caused by mechanical trauma to the spinal cord. Novel therapeutic approaches are continuously explored to enhance spinal cord regeneration and functional recovery. Purpose: In this study, we investigated the efficacy of the poly(vinyl alcohol) and chitosan (CS) (PVA/CS) scaffold loaded with different thymol concentrations (5, 10, and 15% wt%) in a rat compression model for SCI treatment compare to other (e.g., thymol and scaffold) control groups. Results and Discussion: The thymol-loaded scaffold exhibited a smooth surface and a three-dimensional nanofibrous structure with nanoscale diameter. The conducted analyses verified the successful incorporation of thymol into the scaffold and its high water absorption, porosity, and wettability attributes. Behavioral assessment of functional recovery showed improving sensory and locomotor impairment. Furthermore, histopathological examinations indicated the regenerative potential of the thymol-loaded nanofiber scaffold, as evidenced by reduced glial scar formation and enhanced axonal regrowth in the sciatic nerve injury. Conclusion: Therefore, these findings suggest that the thymolloaded nanofibrous scaffolds have promising pharmacological activities for alleviating neuropathic pain and addressing complications induced by SCI.