Rat model for chronic tympanic membrane perforation and the efficiency of chitosan patch scaffold for treatment

摘要

The common treatments of chronic otitis media (COM) are surgeries including myringoplasty or tympanoplasty. However, for some patients the risks, costs, and inconvenience of an operation are of significant concerns. Therefore, the development of a simple, effective, and inexpensive outpatient procedure has been needed as the substitute for surgical procedures. Unfortunately, however, reliable models for chronic tympanic membrane (TM) perforation have not yet been established until now. Many attempts have been made for manufacturing chronic TM perforations in animal models; an infolding technique in chinchillas (Amoils et al., 1992), local application of hydrocortisone (Spandow and Hellstrom, 1993), local application of mitomycin C in rats (Estrem and Batra, 1999), local application of mitomycin C and hydrocortisone (Cui et al., 2005), and local application of 5-fluorouracil (Cincik et al., 2005), etc. Several scaffolds, such as hydrogels or collagen, that could stimulate tympanic regeneration, guide eardrum growing, or replace the perforated defects, have recently been introduced for alternative methods of paper patches. However, all previous methods have disadvantages as well as advantages and limitations for clinical application in cases of chronic TM perforations. Chitosan has been suggested to have the proper characteristics as a scaffold for treatment of TM perforation (Kim et al., 2008). We previously showed that a chitosan patch scaffold (CPS) was more effective than spontaneous healing to repair acute and traumatic TM perforations (Kim et al., 2008). The objectives of this study were to develop animal models for chronic TM perforations which could be maintained for at least more than 8 weeks and to assessed the healing efficiency of CPS using animal models by comparing with paper patches.