Chronic tympanic membrane (TM) perforations can cause otorrhea. To date, various types of tissue engineering techniques have been applied for the regeneration of chronic TM perforations. However, the application of nanofibers with radially aligned nanostructures and the simultaneous release of growth factors have never been applied in the regeneration of chronic TM perforations. Here, epidermal growth factor (EGF)–releasing radially aligned nanofibrous patches (ERA‐NFPs) are developed and applied for the regeneration of chronic perforated TMs. First, radial alignments and the presence of EGF in the ERA‐NFPs are analyzed. EGF is confirmed to be released from the ERA‐NFPs until 8 weeks. In an in vitro study, cell viability assay, immunocytochemistry, and wound‐healing assay indicate rational enhancement of healing by the combination of radial alignments and EGF release. The effect of ERA‐NFPs on TM cells is revealed by quantitative real‐time polymerase chain reaction. An in vivo animal study shows that the ERA‐NFPs effectively stimulates the healing of the chronic TM perforations. The TMs healed by ERA‐NFPs show histological properties similar to those of normal TMs. These results indicate that ERA‐NFPs may be an efficient platform for the regeneration of chronic TM perforations, laying the foundation for nonsurgical treatments of chronic otitis media.

Aminoglycoside antibiotics including gentamicin (GM) induce delayed ototoxic effects such as hearing loss after long-term use, unlike the early-onset ototoxicity caused by cisplatin. The purpose of the study was to identify the mechanism of the delayed GM-induced ototoxicity by exploring the role of autophagy in vitro and in vivo. Treating HEI-OC1 auditory cells with GM led to a time-dependent increase of the autophagosome marker LC3-II, which was accompanied by cell death. In contrast, cisplatin and penicillin caused a rapid increase and had no effect on LC3-II levels, respectively. LC3-II-expressing autophagosomes co-localized with the labeled GM. GM-treated autophagosomes expressed reduced levels of Rab7, which is necessary for the fusion of autophagosomes with lysosomes. When the autophagic flux enhancer rapamycin was applied to GM-treated cells, Rab7 and the lysosomal enzyme cathepsin D were upregulated, and increased cell survival was observed. In animal studies, the intraperitoneal injection of GM worsened hearing thresholds and induced the accumulation of LC3 in the organ of Corti. This hearing impairment was attenuated by rapamycin. These findings suggest that the delayed onset-ototoxicity of GM may be closely related to the accumulation of autophagosomes via impaired autophagy. This GM-induced auditory cell death could be inhibited by enhancing autophagic flux.

Mastoidectomy, the removal of infected mastoid bones, is a common surgical procedure for the treatment of chronic otitis media. Persistent and recurrent otorrhea and accumulation of keratin debris following open cavity mastoidectomy are still bothersome issues for both patients and otologists. In this study, we used human ear adipose-derived stromal cells (hEASCs) in combination with polycaprolactone (PCL) scaffolds and osteogenic differentiation medium (ODM) to regenerate temporal bone defects. The hEASCs showed stem cell phenotypes, and these characteristics were maintained up to passage 5. Mastoid bulla and cranial bone defects were induced in Sprague-Dawley rats using AgNO and burr hole drilling, respectively, and the rats were then divided into five groups: (1) control, (2) hEASCs, (3) hEASCs + ODM, (4) hEASCs + PCL scaffolds, and (5) hEASCs + PCL scaffolds + ODM. Osteogenesis was evaluated by micro-computed tomography and histology. Compared with the control group, the groups transplanted with hEASCs and PCL scaffolds had significantly higher bone formation along the periphery of the mastoid bulla area. Moreover, ODM synergistically enhanced bone formation in mastoid bulla defects. Our results suggest that combining hEASCs with PCL scaffolds represents a promising method for anatomical and functional reconstruction of postoperative temporal bone defects following mastoidectomy. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3493-3501, 2017.

Chronic tympanic membrane perforation is a tubotympanic disease caused by traumatic or inflammatory factors. To date, numerous therapeutic methods have been used to heal tympanic membrane perforations. However, stem cell-based therapies have been used only rarely for the regeneration of chronic tympanic membrane perforations, because tympanic membrane is always exposed to the external environment. Therefore, the use of latent stem cells to treat the tympanic membrane may be possible for the regeneration of chronic tympanic membrane perforations. In the present study, insulin-like growth factor-binding protein 2 (IGFBP2), a cytokine known for stimulating latent epidermal stem cells, was incorporated into chitosan patch scaffolds (CPSs). The IGFBP2-incorporated CPSs (IGFBP-CPSs) were applied to chronic tympanic membrane perforations as a novel therapeutic strategy and stem cell stimulation technique. The IGFBP-CPSs were successfully fabricated and their morphological and mechanical properties evaluated. We conducted an in vitro study to evaluate the release of IGFBP2, as well as analyses of cell viability and wound healing. In rats with chronic tympanic membrane perforations, we found that the IGFBP-CPSs group had a higher success rate (43.8%) than the spontaneous healing group (20.8%). Histological analysis showed that IGFBP-CPSs successfully regenerated tympanic membrane tissues. This stem cell-based method may therefore be a novel and useful therapy for the regeneration of chronic tympanic membrane perforations.

Nonjunctional Cx43 conditions were prepared by low confluence culture (5 × 10/cm) or a trafficking inhibitor, brefeldin A (BFA), in auditory cells, and short lengthened Cx43s with amino-terminal (NT; amino acids 1-256) or carboxy-terminal (CT; amino acids 257-382) were transfected into Cx-deficient HeLa cells to avoid gap junction formation. Knockdown of nonchannel Cx43 (small interfering RNA [siRNA]) inhibited Cis-diamminedichloroplatinum (cisplatin)-induced cell death regardless of gap junction formation; however, a gap junction blocker, 18 alpha-glycyrrhetinic acid (18α-GA), showed inhibitory effect only under the junctional condition. BFA did not show any additive influence on the inhibitory effect of siRNA Cx43. Shortened Cx43-transfected HeLa cells also resulted in a significant increase in cell death under cisplatin. In the animal studies with cisplatin-treated rats, hearing thresholds of auditory brainstem response were significantly preserved by a gap junction blocker, carbenoxolone, showing much more preserved stereocilia of hair cells in scanning electron microscopic findings. Innovation and Conclusion: Cx43 plays a proapoptotic role in cisplatin-induced auditory cell death in both junctional and nonjunctional conditions. Targeting the Cx-mediated signaling control may be helpful in designing new therapeutic strategies for drug-induced ototoxicity. Antioxid. Redox Signal. 25, 623-636.