Perspectives on adipose-derived stem/stromal cells as potential treatment for scarred vocal folds: opportunity and challenges.

Regenerative therapy using stem cells for the treatment of vocal fold wound healing and fibrosis is a very active area of research in Otolaryngology. Although modern phonosurgical methods can deal with many types of vocal fold pathology, vocal fold scar remains a clinical challenge. Trauma (e.g. vocal abuse, phonosurgery) and inflammation (e.g. laryngitis) are the two main causes of the vocal fold scarring. Several recent reviews detail the problem of vocal fold scarring and the array of possible solutions under investigation. The search for solutions includes autologous tissues, biomaterial implants, growth factors, anti-fibrotic agents and stem cells. This review focuses on emerging research on stem cells for vocal fold regeneration and our own studies of interactions between adipose-derived stem/stromal cells and vocal fold fibroblasts using an in vitro model. While clearly an opportunity, the challenging approach of treating vocal scarring using ASCs has just started. For future in vivo studies, improvements in cell viability and markers of stem-cell differentiation into normal fibroblasts are needed. The roles of stem cell-derived cytokines in paracrine signaling need to be further explored at a cellular level in vitro, and then extended to in vivo experiments.