Author(s)
Gabriela L. Bobarnac Dogaru, BS
Alireza Shokrani, MD MS
Roseanne Y. Hui, BA
Michael Cowan, MS
Jon-Paul Pepper, MD
Affiliation(s)
Keck School of Medicine of the University of Southern California
Abstract:
Educational Objective: At the conclusion of this presentation, the participants should be able to discuss the role of Gli1+ mesenchymal stem cells in the regeneration of the facial nerve after injury. Objectives: Facial nerve paralysis is a significant cause of morbidity, affecting speech, oral competence, vision, and emotional expression. Extensive efforts have been undertaken to determine the cellular events that occur during nerve regeneration, in hopes of finding molecular therapeutic targets to improve this process. Increasingly, non-neural cell lineages are recognized as having critical roles in the process of nerve regeneration. However, little is known about the role of mesenchymal stem cells (MSCs). This is partly due to the lack of known in vivo markers that allow cell fate tracing. Recently, a population of in vivo MSCs was identified in the perivascular space of the mouse incisor, identified by the marker Gli1. Here, we explored the role of Gli1+ MSC's in a mouse model of facial nerve regeneration. Study Design: Animal research study. Methods: We used a transgenic mouse line with an inducible reporter for lineage tracing of Gli1+ cells (Gli1-CRE;Tdt), and induced a unilateral facial nerve cut injury, using the contralateral side as a control. We analyzed the nerve via immunohistochemistry at 1 day, 1 week, 2 weeks, and 4 weeks after injury. Results: There was a significant increase in Gli1+ cells both at the site of injury and within the distal nerve segment. Preliminary results show a subpopulation of these cells to be NG2+ pericytes. The Gli1+ cells do not appear to be Schwann cells, as shown by S100 and p75 staining. Conclusions: These findings represent a new role in nerve regeneration for a previously undescribed cell population that may represent a novel therapeutic target.