Pulsed Dye Laser-Induced Inflammatory Response and Extracellular Matrix Turnover in Rat Vocal Folds and Vocal Fold Fibroblasts

Background and Objectives: Disruption of the vocal fold extracellular matrix (ECM) can induce a profound and refractory dysphonia. Pulsed dye laser (PDL) irradiation has shown early promise as a treatment modality for disordered ECM in patients with chronic vocal fold scar; however, there are limited data addressing the mechanism by which this laser energy might induce cellular and extracellular changes in vocal fold tissues. In this study, we examined the inflammatory and ECM modulating effects of PDL irradiation on normal vocal fold tissues and cultured vocal fold fibroblasts (VFFs). Study Design/Materials and Methods: We evaluated the effects of 585 nm PDL irradiation on inflammatory cytokine and collagen/collagenase gene transcription in normal rat vocal folds in vivo (3-168 hours following delivery of similar to 39.46 J/cm(2) fluence) and VFFs in vitro (372 hours following delivery of 4.82 or 9.64 J/cm(2) fluence). We also examined morphological vocal fold tissue changes 3 hours, 1 week, and 1 month post-irradiation. Results: PDL irradiation altered inflammatory cytokine and procollagen/collagenase expression at the transcript level, both in vitro and in vivo. Additionally, PDL irradiation induced an inflammatory repair process in vivo that was completed by 1 month with preservation of normal tissue morphology. Conclusions: PDL irradiation can modulate ECM turnover in phenotypically normal vocal folds. Additional work is required to determine if these findings extend to disordered ECM, such as is seen in vocal fold scar. Lasers Surg. Med. 41:585-594, 2009. (C) 2009 Wiley-Liss, Inc.