Abstract
Background: The quality of healing of peripheral nerve injuries (PNI) remains a common challenge causing pain and poor quality of life of millions of people and animals annually.
Aims: The objectives of this study were to evaluate the healing quality of facial nerve injury in a dog model following local treatment using autologous injection of platelet-rich plasma (PRP) or bone marrow-derived mesenchymal stem cells (BM-MSCs) at the injury site in combination with the application of an autologous saphenous vein graft as a conduit.
Methods: A total of 20, apparently healthy adult Mongrel dogs were randomly divided into 4 equal groups. Dogs in groups 1, 2, and 3 were subjected to facial nerve neurectomy and saphenous vein conduit graft implantation at the site of facial nerve injury. Dogs in groups 2 and 3 received 1 ml of autologous PRP and BM-MSCs, respectively. Injections were performed directly in the vein conduit immediately after nerve injury. Dogs in group 1 (grafted but not treated; control) received only an autologous vein graft and those in group 4 (normal control) received no graft and no PRP or BM-MSCs treatment. The dogs were monitored daily for 8 weeks after surgery. Clinical evaluation of the facial nerve including lower eyelid, ear drooping, upper lip, and tongue functions was performed once per week using a numerical scoring system of 0 to 3. At the end of the study period (week 8), the facial nerve injury site was evaluated grossly for the presence of adhesions using a numerical scoring system of 0 to 3. The facial nerve injury site was histopathologically evaluated for the presence of perivascular mononuclear cell infiltration, fibrous tissue deposition, and axonal injury using H & E- stained tissue sections.
Results: Clinically, BM-MSCs treated dogs experienced significant (p < 0.05) improvement in lower eyelid, ear, lip and tongue functions 4 weeks postoperatively in comparison to other groups. Grossly, the facial nerve graft site in BM-MSCs treated group showed significantly (p < 0.05) less adhesion scores compared to other groups. Histopathologically, there was significantly (p < 0.05) less perivascular mononuclear cell infiltration, less collagen deposition, and more normal axons at the facial nerve injury site in BM-MSCs treated group compared to other groups.
Conclusion: Results of this study showed clinically significant enhancement of nerve regeneration by the application of autologous BM-MSCs and autologous vein grafting at the site of facial nerve injury. However, further clinical trials are warranted before this application can be recommended in the treatment of traumatic nerve injuries in the field.

Key words: Neuropathies, Pain, Nerve regeneration, Pluripotent cells, Nerve graft.