Mesenchymal Stem Cells for Treatment of Delayed-Healing Tympanic Membrane Perforations Using Hyaluronate-based Laminas as a Delivery System: An Animal Model With Histopathologic Study

Hypothesis: Bone marrow derived-mesenchymal stem cells (BM-MSCs) improve the healing of chronic tympanic membrane perforations (cTMPs) in an animal model. Background: cTMPs generate significant morbidity and reduced quality of life, usually requiring surgical assistance. With growing interest in alternative therapies, we sought to evaluate the effect of BM-MSC-therapy on the healing of cTMPs. Methods: Sixty cTMPs were established in C57Bl/6 mice and randomized into four groups: hyaluronate scaffold as graft plus BM-MSCs (n = 19 ears), scaffold plus cell culture media (n = 16), scaffold plus phosphate-buffered saline (PBS, n = 12), and no intervention (n = 13). Hyaluronate scaffolds with or without BM-MSCs were applied on 8-week perforated eardrums. After a blinded assessment of perforation sizes at baseline and 2 weeks after treatment, mean perforation reduction rates (%) were compared. Histology characterization was then performed. Results: Mean perforation size reduction rates were significantly higher for cTMPs that received scaffolds plus BM-MSCs (Student's t test, p = 0.0207, 12.3% [95% CI: 7.8-16.7]) and scaffolds plus cell culture media (p = 0.0477, 11.3% [95% CI: 4.4-18.2]) when compared with no intervention (4.2% [95% CI: 1.2-7.2]). This was not observed when treating eardrums with scaffolds plus PBS (7.3% [95% CI: 2.7-11.9]). On histology, BM-MSC-treated eardrums demonstrated restoration of the trilaminar configuration and reduced inflammatory changes, while other groups developed tissue architecture disorganization and hypercellular infiltrates surrounding the perforation site. Conclusions: BM-MSCs and cell culture media equivalently increased cTMP healing rates. Cell-based therapy conferred a restoration of the trilaminar configuration of the eardrum with relatively compact and organized fibrous layers.