Objective: Evaluate the efficacy of a photocrosslinkable gel patch for repairing tympanic membrane (TM) perforations using a minimally invasive procedure.
Methods: 38 adult male chinchillas underwent bilateral TM perforation via CO2 laser (n = 76 TMs). Eight weeks post-perforation induction, either a gel patch (n = 26) or EpiDisc (n = 12) was applied to the perforation through the ear canal. Perforation margins were not abraded prior to gel patch application in order to make the procedure minimally invasive. During the study, the application process was refined, and 9 of 26 gel-treated TMs received a second gel-patch augmentation. Perforations were observed for 14 weeks post-treatment to determine healing rates, after which animals were euthanized and their TMs and cochlea removed for histological analysis.
Results: 38 perforations (50%) persisted for 8 weeks without manipulation. Healing rates stabilized within three weeks post-treatment. Of the gel-treated TMs, 14 TMs healed after one application, 7 TMs healed after a second application, and 5 TMs did not heal, yielding an 81% total healing rate. Six of 12 EpiDisc-treated TMs healed (50%). There was no statistical difference (p = 0.06) in perforation size between gel-treated (25.1 ± 12.5% total TM area) and Epidisc-treated (36.4 ± 22.5). The largest perforation healed with gel patch was 60% total TM area. Histological analysis showed gel-treated TMs to have trilaminar regeneration with substantial lamina propria thickness. Gel-treated TMs had thickness of statistical equivalence to untreated TMs (47.1 ± 29.0 and 54.8 ± 12.1 μm, respectively (p = 0.40)). EpiDisc-treated TMs showed a cell monolayer of substantially less thickness (9.04 ± 6.26 μm, p < 0.05) than gel-treated TMs. No evidence of ototoxicity was present in cochlea from either gel patch or Epidisc treatment.
Conclusions: The gel is promising regarding thickness and trilaminar regenerated tissue, perhaps due to the biomechanical properties of the gel, and further refinements in the material and technique are anticipated to increase ease and efficacy of treatment while minimizing complications.
Keywords: Animal model; Biomaterial; Hydrogel; Myringoplasty; Tympanic membrane perforation.
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