gms | German Medical Science

Introduction: Transplantation of olfactory ensheathing cells (OECs) into experimental models of spinal cord injury (SCI) has demonstrated improvement in functional outcome and currently clinical studies using OECs for SCI patients are ongoing. The precise mechanism for the improved functional outcome is not clear, but several mechanisms including induction of axonal regeneration and sprouting, neuroprotection and remyelination have been suggested. While most experimental transplantation studies using OECS derived them from olfactory bulb (OB-OECs), olfactory mucosa-derived OECs (OM-OECs) can be derived from nasal biopsy and therefore present as a more tractable and safe source of OECs for potential autologous clinical use. Yet, the relative efficacy of OECs prepared of the olfactory bulb (OB-OECs), olfactory mucosa (OM-OECs) and Schwann cells (SCs) has not been established.In this study the relative remyelinating capacity of autologous OB-OECs, OM-OECs, and fibular nerve SCs from large animal transplanted into demyelinated spinal cord was assessed.

Material and methods: In this study the relative remyelinating capacity of highly purified and characterized canine OB-OECs, OM-OECs and SCs were is was assessed following transplantation into a demyelinated spinal cord lesion in the in, the extend of remyelination of those three cells groups was analyzed by quantitative mophometric analysis.

Results: Histological analysis indicated that purified canine OECs (mucosal and bulb) and SCs survived the transplantation procedure and contributed to subsequent remyelination. While all three cell types remyelinated spinal cord axons, the OECs from olfactroy bulb and SCs were much more effective in remyelinating the spinal cord axons than the OECs from the olfactory mucosa. The reason for this difference as indicated by in vitro migration assays suggested that reduced migration within the lesion may account for the lower level of remyelination. The motility of the glial cell type correlated to their capability of remyelinating the lesion volume in the spinal cord, with OECs from the bulb and Schwann cells as the most efficient ones. Thus, canine OECs have an intrinsic capacity to remyelinate spinal cord axons, but purified OECs from the olfactroy bulb display greater myelinating capacity than mucosa OECs in vivo and greater migration in vitro.

Conclusion: These results on the remyelination capacity of the three cell types have implications for the potential clinical use of OECs as therapeutic tool. If remyelination is the primary target for a cellular therapy, than, OECs from the olfactory bulb and SCs would be more desirable than the more accessible mucosa OECs. This result would suggest that derivation of OECs from nasal mucosa which is associated with low morbidity may not be an optimal derivation site.