Cell component changes in an acute and chronic vocal fold (VF) scar rat model

Abstract

Problem: Knowledge of wound healing is essential to treatment of VF scarring. Fibroblasts and myofibroblasts are thought to be important constituents in wound healing; the former produces extracellular matrix (ECM), and the latter is closely related to wound contraction. Yet little is known about their expression patterns following VF injury. Methods: Using a 1.9 mm diameter telescope for guidance, VF stripping was performed unilaterally in 48 Sprague-Dawley rats. Larynges were harvested at 8 time points (1 day, 3 days, 5 days, 7 days, 2 weeks, 4 weeks, 8 weeks, and 12 weeks) and the scarred and normal VFs were histologically analyzed. Immunohistochemical staining for vimentin, and alfa smooth muscle actin (SMA), a marker of myofibroblast, were performed. Results: In normal VFs, vimentin-positive cells existed in the deep layer and the basement membrane zone of the lamina propria (LP). Most of the alfa-SMA-positive cells highlighted capillaries in the deep and middle layer of the LP and very few single cells were evident. Vimentin-positive cells increased from day 3 to day 14, and then returned to the normal level after 8 weeks. Alfa-SMA-positive cells increased from day 3 to 4 weeks and then returned to normal levels after 8 weeks. At day 5 and day 7, many single cells were evident in the scarred VFs in addition to many collections of cells that depicted the capillaries. These single cells disappeared by day 14. Conclusion: Myofibroblasts were evident at day 5 and day 7 after injury, which suggests that wound contraction in VF occurs in an early phase of wound healing. Significance: Our findings imply that there may be a critical window for VF scar prevention present in the early stage of wound healing. Support: None reported.