A novel silk-based vocal fold augmentation material: 6-month evaluation in a canine model.

Objectives: Ideal long-term vocal fold augmentation materials should be biocompatible, easily administered, allow tissue integration for long-term effect, and remain at the site of injection. A novel silk protein particle suspended in hyaluronic acid (Silk-HA) has been developed specifically for vocal fold augmentation to address this unmet need. This article presents the 6-month, preclinical findings of a canine vocal fold injection trial for Silk-HA.

Methods: Twelve beagle dogs were injected transorally in the lateral/deep aspect of their right thyroarytenoid muscles with 0.3 cc of Silk-HA or calcium hydroxylapatite in carboxymethyl cellulose (CaHA-CMC). The Silk-HA particle injectable was delivered via a custom catheter, whereas CaHA-CMC was delivered through a commercially available malleable needle. The six dogs from each material group were sacrificed 6 months from the injection date for the evaluation of implant longevity, immune response, and material migration.

Results: Silk-HA provides immediate medialization of the right vocal fold, lasting for a minimum of 6 months in a canine model. Silk-HA and CaHA-CMC both demonstrate similar inflammatory responses. The Silk-HA was shown to remain without migration at the site of injection in all six canine subjects, whereas CaHA-CMC demonstrated migration in four of the six canines. In two canines implanted with CaHA-CMC, material was discovered to migrate to the retropharyngeal lymph nodes.

Conclusion: In a canine subject model, the Silk-HA material compares favorably in terms of longevity and immune response to CaHA-CMC. The lack of migration of the Silk-HA material demonstrates a promising potential for vocal fold injection in the clinic.

Level Of Evidence: NA Laryngoscope, 129:1856-1862, 2019.