Objectives/hypothesis: The aims were to analyze if improved histological and viscoelastic properties seen after injection of human mesenchymal stem cells (hMSCs) in scarred vocal folds (VFs) of rabbits are sustainable and if the injected hMSCs survive 3 months in the VFs.
Study design: Experimental xenograft model.
Methods: Eighteen VFs of 11 New Zealand white rabbits were scarred by a bilateral localized resection. After 3 months the animals were sacrificed. Twelve VFs were dissected and stained for histology, lamina propria thickness, and relative collagen type I analyses. The hMSCs survival was analyzed using a human DNA-specific reference probe, that is, fluorescence in situ hybridization staining. Viscoelasticity, measured as the dynamic viscosity and elastic modulus, was analyzed in a parallel-plate rheometer for 10 VFs.
Results: The dynamic viscosity and elastic modulus of hMSC-treated VFs were similar to that of normal controls and significantly improved compared to untreated controls (P < .05). A reduction in lamina propria thickness and relative collagen type 1 content were also shown for the hMSC-treated VFs compared to the untreated VFs (P < .05). The histological pictures corresponded well to the viscoelastic results. No hMSCs survived.
Conclusions: Human mesenchymal stem cells injected into a scarred vocal fold of rabbit enhance healing of the vocal fold with reduced lamina propria thickness and collagen type I content and restore the viscoelastic function.