Functional modulation of satellite cells in long-term denervated human laryngeal muscle

To evaluate the effects of long-term denervation on satellite cells (SCs) as myogenic stem cells in human posterior cricoarytenoid (PCA) muscle.

Histological investigation of SCs and quantitative assessment of myoD and myogenin, which are two key myogenic regulatory factors.

According to the course of denervation, denervated PCA muscles of 58 patients who suffered from traumatic unilateral vocal cord paralysis were divided into four groups: group A (6-12 months, 15 cases), group B (13-24 months, 17 cases), group C (25-36 months, 14 cases), and group D (more than 36 months, 12 cases). Normal PCA muscles (12 cases) were used as a control group. Immunofluorescence labeling was used to visualize the SCs. Transcription and protein expression levels of myoD and myogenin were assessed using real-time quantitative polymerase chain reaction and Western blots, respectively.

MyoD- and myogenin-positive cells and embryonic myosin heavy chain-positive myofibers were detected in group A and most of the samples of group B. Transcription levels of myoD and myogenin were highly upregulated in groups A and B, whereas groups C and D showed no significant difference as compared to control. Protein expression levels of myoD and myogenin peaked in group A, which was significantly different than group B. In contrast, no expression was observed in the other groups.

Activated SCs contribute to regenerative myogenesis in denervated laryngeal muscles through compensatory mechanisms. Laryngeal muscles exhibit persistent regenerative potential from the viewpoint of muscle SCs after less than 2 years of denervation.