Conditioned medium of olfactory ensheathing cells promotes the functional recovery and axonal regeneration after contusive spinal cord injury

Objective: To investigate the effectiveness and the potential role of olfactory ensheathing cell conditioned medium (OEC-M) to treat contusive spinal cord injury (SCI). Methods: The contusive SCI model was established by NYU weight-drop impactor at T10 segment. Male Sprague-Dawley rats received intraperitoneal injection of control medium (Con-M, n=18), low dose OEC-M (n=18) and high dose OEC-M (n=18). Immunofluorescence was performed to identify the purity of cultured OECs. BBB score was used to assess the functional recovery. BDNF concentrations of OEC-M, Con-M and rats plasma samples were determined by ELISA. Conventional MR1 and diffusion tensor tractography (DTT) were applied to visualize the repair process of SCI. Diffusion tensor imaging (DTI) and immunohistochemistry of NF200 were carried out to evaluate the axonal regeneration. Results: After the systemic delivery of treatment, BBB scores and BDNF levels in peripheral blood were significantly higher in OEC-M treated groups than in Con-M group. MRI and DTT demonstrated a better radiological recovery after SCI in OEC-M treated groups and higher dose of OEC-M were accompanied with better outcomes. DTI and NF200 staining revealed the OEC-M treatment promoted axonal regeneration around the injury epicenter but no axonal regeneration was observed at the lesion site. Conclusion: The results indicate that the OEC-M treatment improves the functional recovery and promotes the axonal regeneration around the injury epicenter after contusive SCI. This strategy represents a novel cell-free OEC based therapy to effectively treat SCI.