Repair of Tympanic Membrane Perforations with Customized Bioprinted Ear Grafts Using Chinchilla Models

Abstract

The goal of this work is to develop an innovative method that combines bioprinting and endoscopic imaging to repair tympanic membrane perforations (TMPs). TMPs are a serious health issue because they can lead to both conductive hearing loss and repeated otitis media. TMPs occur in 3-5% of cases after ear tube placement, as well as in cases of acute otitis media (the second most common infection in pediatrics), chronic otitis media with or without cholesteatoma, or as a result of barotrauma to the ear. About 55,000 tympanoplasties, the surgery performed to reconstruct TMPs, are performed every year, and the commonly used cartilage grafting technique has a success rate between 43% and 100%. This wide variability in successful tympanoplasty indicates that the current approach relies heavily on the skill of the surgeon to carve the shield graft into the shape of the TMP, which can be extremely difficult because of the perforation's irregular shape. To this end, we hypothesized that patient specific acellular grafts can be bioprinted to repair TMPs. In vitro data demonstrated that our approach resulted in excellent wound healing responses (e.g., cell invasion and proliferations) using our bioprinted gelatin methacrylate constructs. Based on these results, we then bioprinted customized acellular grafts to treat TMP based on endoscopic imaging of the perforation and demonstrated improved TMP healing in a chinchilla study. These ear graft techniques could transform clinical practice by eliminating the need for hand-carved grafts. To our knowledge, this is the first proof of concept of using bioprinting and endoscopic imaging to fabricate customized grafts to treat tissue perforations. This technology could be transferred to other medical pathologies and be used to rapidly scan internal organs such as intestines for microperforations, brain covering (Dura mater) for determination of sites of potential cerebrospinal fluid leaks, and vascular systems to determine arterial wall damage before aneurysm rupture in strokes.

Animal Model of Chronic Tympanic Membrane Perforation

“…There is growing interest in finding nonsurgical alternatives to tympanoplasty. Growth factors (Santa Maria et al, ; Wang et al, ) and stem cells (Farrior, ; Rahman et al, ; Kuo et al, ) have been shown beneficial in preclinical and clinical studies. We previously reported that topical application of mesenchymal stem cells embedded in a hyaluronate scaffold improved the healing rate of TMP closure and yielded a histologically normal neotympanum in an animal model of acute TMP (Goncalves et al, )), but many methodological questions still need to be answered before molecular and cell‐based therapies find their clinical application.…”

“…Animal models of delayed TMP have been recently described (Santa Maria et al, ; Santa Maria et al, ; Wang et al, ) showing varying results with controversy still existing on the minimal time of perforation patency to be considered clinically relevant. Authors have suggested that a patency period ranging from 8 to12 weeks is the minimum time for a perforation to be considered chronic (Truy et al, ; Deng et al, ; Santa Maria et al, ; Wang et al, ; Kuo et al, ). Techniques used for delaying spontaneous closure of TMP included infolding the edges of the perforation (Emami et al, ), thermal injury (Amoils et al, ), re‐myringotomy (Wang et al, ), topical application of agents that delay epithelization such as dexamethasone (Wang et al, ), mitomycin C (Wang et al, ), hydrocortisone (Spandow and Hellstrom, ), and glutaraldehyde (Truy et al, ).…”

Trophoblast–endothelium signaling involves angiogenesis and apoptosis in a dynamic bioprinted placenta model

“…Gelatin methacrylate (GelMA) was synthesized according to previously published methods (C.-Y. Kuo et al, 2017).…”

Regeneration – eine neue therapeutische Dimension in der Hals-Nasen-Ohrenheilkunde

“…Unfortunately, the preclinical rationale of this study and its design is imprecisely described. In preclinical research, 3D bioprinting is also used to regenerate the tympanic membrane 108 , which could be shown in the closure of chinchilla tympanic membrane defects. Even decellularized tissue has already been analyzed for tympanoplasty in preclinical studies and in some clinical trials 109 110 .…”

“…Leider bleiben auch hier die präklinische Rationale und das Studiendesign ungenau. In der präklinischen Forschung wird auch für die Regeneration des Trommelfells das 3D-Bioprinting verwendet 108 und konnte an Chinchillas für den Verschluss von Trommelfelldefekten verwendet werden. Auch dezellularisierte Gewebe wurden bereits für die Tympanoplastik in präklinischen Untersuchungen und auch einigen klinischen Studien analysiert 109 110 .…”