Repair of transected facial nerve with mesenchymal stromal cells: histopathologic evidence of superior outcome.

OBJECTIVES/HYPOTHESIS: Despite advanced surgical techniques, clinical results of the transected facial nerve are still far from the desired outcome. Mesenchymal stromal cells (MSCs) were shown to transdifferentiate into Schwann cells and express some growth factors beneficial in peripheral nerve injury. We aimed to document histopathological improvement obtained from application of the homograft bone marrow-derived MSCs immediately after conventional anastomosis of a transected facial nerve branch in rats, and to compare the results with those nerves anastomosed only. STUDY DESIGN: Animal, prospective, and controlled study. METHODS: The study was performed in 15 rats. The right buccal branch was completely transected and repaired with epineural sutures. The right-side anastomosis was additionally treated with MSCs thereafter. The right marginal mandibular branch was kept intact, but in contact with MSCs. The left buccal branch was transected and repaired in a similar fashion except for MSC application. The left-side marginal mandibular branch was left intact. Rats were sacrificed at month 1, 3, and 6. Four branches of each rat were sampled, and nerve segments distal to the anastomosis were histopathologically examined. RESULTS: The examination revealed that intact nerve segments and nerve segments in contact with MSCs had completely normal appearance regardless of the time interval. Samples from the nerves anastomosed and treated with MSCs did better than those nerves anastomosed only in terms of axonal organization and myelin thickness. CONCLUSIONS: This preliminary report witnessed beneficial effects of MSCs application onto the injured facial nerve as evidenced by the histopathological examination.