Vocal fold tissue repair in vivo using a synthetic extracellular matrix

Chemically modified hyaluronic acid (HA)-gelatin hydrogels have been documented to support attachment, growth, and proliferation of fibroblasts in vitro and to facilitate repair and engineering of tissues in vivo. The objective of this study was to determine the optimal composition of a synthetic extracellular matrix (sECM) that would promote wound repair and induce tissue regeneration in a rabbit vocal fold wound healing model. The sECM was formed using a thiol-modified semisynthetic glycosaminoglycan (GAG) derived of HA (Carbylan(TM)-SX) mixed with a thiolated gelatin derivative, co-cross-linked with poly(ethylene glycol) diacrylate to form Carbylan-GSX. Forty rabbits underwent vocal fold biopsy bilaterally. Rabbits were treated with Carbylan-SX, which lacks gelatin, or with Carbylan-GSX with different gelatin concentrations (2.5%, 5%, 10%, and 20%) via unilateral injection of the vocal fold at the time of biopsy. Saline was injected in the contralateral vocal fold as a control. Three weeks after biopsy and injection, animals were euthanized and mRNA levels of procollagen type 1, fibronectin, transforming growth factor beta 1 (TGF-beta 1), fibromodulin, HA synthase 2, hyaluronidase 2, and tissue biomechanics were evaluated. Hyaluronidase mRNA levels were found to be significantly elevated in for Carbylan-GSX 20% w/w gelatin compared to controls. Both Carbylan-SX and Carbylan-GSX significantly improved tissue elasticity and viscosity. Carbylan-GSX containing 5% w/w gelatin showed the most promise as a scaffold material for vocal fold tissue regeneration.