Ultra structure of the Middle Ear Mucosa

Analysis of the potential of human cultured nasal epithelial cell sheets to differentiate into airway epithelium

Understanding the expected efficacy and safety of a new regenerative therapy requires analysis of the fate of the transplanted cell graft. We have shown that transplantation of autologous cultured nasal epithelial cell sheets onto the middle ear mucosa can improve middle ear aeration and hearing. However, it remains unknown whether cultured nasal epithelial cell sheets have the potential to gain mucociliary function in the environment of the middle ear because sampling cell sheets after transplantation is challenging. The present study re-cultured cultured nasal epithelial cell sheets in different culture media and evaluated whether the sheets have the potential to differentiate into airway epithelium. Before re-cultivation, cultured nasal epithelial cell sheets fabricated in keratinocyte culture medium (KCM) contained no FOXJ1-positive and acetyl-α-tubulin-positive multiciliated cells or MUC5AC-positive mucus cells. Interestingly, multiciliated cells and mucus cells were observed when the cultured nasal epithelial cell sheets were re-cultured in conditions that promote differentiation of airway epithelium. However, multiciliated cells, mucus cells and CK1-positive keratinized cells were not observed when cultured nasal epithelial cell sheets were re-cultured in conditions that promote epithelial keratinization. These findings support the suggestion that cultured nasal epithelial cell sheets have the ability to differentiate and gain mucociliary function in response to an appropriate environment (possibly including the environment found in the middle ear) but are unable to develop into an epithelial type that differs from its origins.

Transplantation of a human induced pluripotent stem cell-derived airway epithelial cell sheet into the middle ear of rats

Introduction

Early postoperative regeneration of the middle ear mucosa is essential for the prevention of postoperative refractory otitis media and recurrent cholesteatoma. As a means for intractable otitis media management, we focused on human induced pluripotent stem cell (hiPSC)-derived airway epithelial cells (AECs), which have been used in upper airway mucosal regeneration and transplantation therapy. In this study, we transplanted hiPSC-derived AECs into the middle ear of immunodeficient rats.

Methods

Following the preparation of AEC sheets from hiPSCs, the bilateral middle ear mucosa of X-linked severe combined immunodeficient rats was scraped, and the AEC sheets were transplanted in the ears unilaterally.

Results

Human nuclear antigen (HNA)-positive ciliated cells were observed on the transplanted side of the middle ear cavity surface in three of six rats in the 1-week postoperative group and in three of eight rats in the 2-week postoperative group. No HNA-positive cells were found on the control side. The percentage of HNA-positive ciliated cells in the transplanted areas increased in the 2-week postoperative group compared with the 1-week group, suggesting survival of hiPSC-derived AECs. Additionally, HNA-positive ciliated cells were mainly located at sites where the original ciliated cells were localized. Immunohistochemical analysis showed that the transplanted AECs contained cytokeratin 5- and mucin 5AC-positive cells, indicating that both basal cells and goblet cells had regenerated within the middle ear cavity.

Conclusions

The results of this study are an important first step in the establishment of a novel transplantation therapy for chronic otitis media.

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hiPSC-derived airway epithelial cells were transplanted into the middle ear of rats.

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Engrafted cells mainly survived in the ciliated region of the middle ear.

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Ciliated, goblet, and basal cells were confirmed in the engrafted cells.

Middle Ear "Adenoma": a Neuroendocrine Tumor with Predominant L Cell Differentiation

This morphological and immunohistochemical study demonstrates that tumors currently known as "middle ear adenomas" are truly well-differentiated epithelial neuroendocrine tumors (NETs) composed of cells comparable to normal intestinal L cells, and therefore, these tumors resemble hindgut NETs. These tumors show consistent expression of glucagon, pancreatic polypeptide, PYY, and the transcription factor SATB2, as well as generic neuroendocrine markers and keratins. The same L cell markers are expressed by cells within the normal middle ear epithelium. These markers define a valuable immunohistochemical profile that can be used for differential diagnosis of middle ear neoplasms, particularly in distinguishing epithelial NETs from paragangliomas. The discovery of neuroendocrine cells expressing the same markers in non-neoplastic middle ear mucosa opens new areas of investigation into the physiology of the normal middle ear and the pathophysiology of middle ear disorders.

Evidence of SARS-CoV-2 Virus in the Middle Ear of Deceased COVID-19 Patients

The presence of SARS-CoV-2 in the middle ear reveals the etiopathogenesis of otitis media in COVID-19, as well as an epidemiological risk during otologic examination and surgical procedures in COVID-19 patients. The study included 8 deceased patients with COVID-19. Tissue samples from the middle ear were subjected to virology, histopathology, scanning (SEM) and transmission (TEM) electron microscopy investigation. Ethmoidal mucosa samples were processed for virology analyses. qPCR resulted positive for 75% of nasal mucosa samples and 50% of middle ear samples. Ct values showed lower viral loads in middle ear samples. A proportion of 66.6% patients with positive results in the nasal mucosa showed positive results in the middle ear, and the subtype analysis of the complete genome sequences indicated B.1.1.7 lineage for all samples. In histopathological and SEM samples, no pathological aspects were identified. TEM revealed on the background of death critical alteration of cellular morphology, suggestive structures resembling SARS-CoV-2, goblet cells and immune cells. SARS-CoV-2 can be present in the middle ear of COVID-19 patients even if there is not clinical evidence of acute otitis media. Otolaryngologists could be particularly exposed to COVID-19 infection.

Middle ear adenoma with neuroendocrine differentiation: Report of a rare case

Middle ear adenoma with neuroendocrine differentiation (MEA-ND) is also called as neuroendocrine adenoma. Neuroendocrine tumors are rarely seen in the head and neck region and are even more rare in the middle ear. Clinical and radiological findings are non-specific and seldom suggest this diagnosis. Nomenclature and behavior of this tumor has been historically controversial. Both epithelial as well as neuroendocrine origin have been suggested. They comprise <2% of all ear tumors and commonly present with unilateral hearing loss, aural fullness, and tinnitus. We present a case report of MEA-ND in a 24-year-old woman who presented with heaviness and tinnitus in the right ear.

Hearing Changes After Intratympanic Steroids for Secondary (Salvage) Therapy of Sudden Hearing Loss: A Meta-Analysis Using Mathematical Simulations of Drug Delivery Protocols

OBJECTIVE

The use of glucocorticoids for secondary (salvage/rescue) therapy of idiopathic sudden hearing loss (ISSHL), including controlled and uncontrolled studies with intratympanic injections or continuous, catheter mediated applications, were evaluated by means of a meta-analysis in an attempt to define optimal local drug delivery protocols for ISSHL.

STUDY DESIGN

A total of 30 studies with 33 treatment groups between January 2000 and June 2014 were selected based on sufficiently detailed description of application protocols. Cochlear drug levels were calculated by a validated computer model of drug dispersion in the inner ear fluids based on the concentration and volume of glucocorticoids applied, the time drug remained in the middle ear, and on the specific timing of injections. Various factors were compared with hearing outcome, including baseline data, individual parameters of the application protocols, calculated peak concentration (Cmax), and total dose (area under the curve, AUC).

RESULTS

There was no dependence of hearing outcome on individual parameters of the application protocol, Cmax or AUC. Hearing gain and final hearing thresholds were independent of treatment delay.

CONCLUSION

Based on the available data from uncontrolled and controlled randomized and non-randomized studies no clear recommendation can be made so far for a specific application protocol for either primary or secondary (salvage) intratympanic steroid treatment in patients with ISSHL. For meta-analyses, change in pure tone average (PTA) may not be an adequate outcome parameter to assess effectiveness of the intervention especially with inhomogeneity of patient populations. Final PTA might provide a better outcome parameter.

Single origin of the epithelium of the human middle ear

OBJECTIVE

The epithelium lining the human middle ear and adjacent temporal bone cavity shows a varying morphological appearance throughout these cavities. Its embryologic origin has long been debated and recently got attention in a newly proposed theory of a dual embryologic origin. The epithelial morphology and its differentiating capabilities are of significance in future mucosa-targeted therapeutic agents and could affect surgical approaches of the temporal bone. This study aims to analyze reported murine histological findings that led to the theory of a dual epithelial embryological origin and immunohistochemically investigate whether such an epithelial embryological origin in the human fetal middle ear could be true.

METHODS

By combining a sagittal sectioning technique and immuno-histochemical staining, a comprehensive immuno-histological overview of the fetal human middle ear during a critical stage of tympanic cavitation was provided. A critical analysis of previously reported findings leading to the theory of a dual epithelial embryological origin and a comparison of these findings to the findings in the human fetal middle ear was performed.

RESULTS

The reported findings and critical analysis provide multiple arguments for an entirely endodermal embryonic origin of the epithelium lining the tympanic cavity.

CONCLUSION

Different morphological epithelial appearances throughout the tympanic and temporal bone cavities could be explained by different stages of epithelial differentiation rather than different embryologic origin and endodermal rupture does not seem to be a necessity for these cavities to form.

On the functional compartmentalization of the normal middle ear. Morpho-histological modelling parameters of its mucosa

BACKGROUND

Middle ear physiology includes both sound pressure transmission and homeostasis of its static air pressure. Pressure gradients are continuously created by gas exchange over the middle ear mucosa as well as by ambient pressure variations. Gas exchange models require actual values for regional mucosa thickness, blood vessel density, and diffusion distance. Such quantitative data have been scarce and limited to few histological samples from the tympanic cavity (TC) and the antrum. However, a detailed regional description of the morphological differences of the TC and mastoid air cell system (MACS) mucosa has not been available. The aim of the present study was to provide such parameters.

METHODS

The study included sets of three histological H&E-slides from 15 archived healthy temporal bones. We performed a comparison of the mucosa morphology among the following regions: (1) anterior TC; (2) inferior TC; (3) posterior TC; (4) superior TC; (5) MACS antrum; (6) superior MACS; (7) central MACS; (8) inferior MACS.

RESULTS

Regions (1)-(3), situated below the inter-attico-tympanic diaphragm, had the largest proportion of high respiratory epithelium, cilia and loose lamina propria within the mucosa, as well as the thickest mucosa and the largest diffusion distance. Regions (6)-(8), situated above the diaphragm, had the thinnest mucosa, the shortest distance to the blood vessels, together with the largest proportion of flat epithelium and very few cilia. Regions (4)-(5), still supradiaphragmatic, had intermediary values for these parameters, but generally closer to regions (6)-(8). The blood vessel density and the proportion of active mucosa were not significantly different among the regions.

CONCLUSION

Mucosa of regions (1), (2) and (3) represented a predominantly clearance-specific morphology, whereas in regions (4)-(8) it seemed adapted to gas exchange. However, the lack of statistically significant differences in blood vessel density and proportion of active mucosa indicated that all regions could be involved in gas exchange with the highest adaptation in the superior MACS. This pattern divides the middle ear functionally along the inter-attico-tympanic diaphragm rather than the anatomical division into TC and MACS.

An Integrative Model Accounting for the Symptom Cluster Triggered After an Acoustic Shock

Acoustic shocks and traumas sometimes result in a cluster of debilitating symptoms, including tinnitus, hyperacusis, ear fullness and tension, dizziness, and pain in and outside the ear. The mechanisms underlying this large variety of symptoms remain elusive. In this article, we elaborate on the hypothesis that the tensor tympani muscle (TTM), the trigeminal nerve (TGN), and the trigeminal cervical complex (TCC) play a central role in generating these symptoms. We argue that TTM overuse (due to the acoustic shock), TTM overload (due to muscle tension), and ultimately, TTM injury (due to hypoxia and "energy crisis") lead to inflammation, thereby activating the TGN, TCC, and cortex. The TCC is a crossroad structure integrating sensory inputs coming from the head-neck complex (including the middle ear) and projecting back to it. The multimodal integration of the TCC may then account for referred pain outside the ear when the middle ear is inflamed and activates the TGN. We believe that our model proposes a synthetic and explanatory framework to explain the phenomena occurring postacoustic shock and potentially also after other nonauditory causes. Indeed, due to the bidirectional properties of the TCC, musculoskeletal disorders in the region of the head-neck complex, including neck injury due to whiplash or temporomandibular disorders, may impact the middle ear, thereby leading to otic symptoms. This previously unavailable model type is experimentally testable and must be taken as a starting point for identifying the mechanisms responsible for this particular subtype of tinnitus and its associated symptoms.

Evidence against the mucosal traction theory in cholesteatoma

OBJECTIVES

To investigate the distribution of ciliated epithelium in the human middle ear and its potential role in the formation of cholesteatoma.

STUDY DESIGN

Comparative human temporal bone study.

METHODS

We selected temporal bones from 14 donors with a diagnosis of cholesteatoma, 15 with chronic otitis media without retraction pockets, 14 with chronic otitis media with retraction pockets, 14 with cystic fibrosis (CF), and 16 controls. We mapped the distribution of the ciliated cells in the mucosal lining of the middle ear and tympanic membrane using three-dimensional reconstruction analysis, and counted the number of ciliated cells in the middle ear mucosa.

RESULTS

Ciliated cells are extremely sparse in the epithelial lining of the lateral surface of the ossicles in the epitympanum and the medial surface of the tympanic membrane. Furthermore, there is a significant decrease in the number of ciliated cells in these areas in temporal bones with cholesteatoma, chronic otitis media, chronic otitis media with retraction pockets, and CF compared to controls. Ciliated cells most commonly are located at the hypotympanum and the Eustachian tube opening but not the tympanic membrane or epitympanum.

CONCLUSION

The paucity of ciliated epithelial cells on the medial side of the tympanic membrane and the lateral surface of the ossicles in the epitympanum in cases with cholesteatoma and/or chronic otitis media do not support the mucosal migration theory of cholesteatoma formation.

LEVEL OF EVIDENCE

NA. Laryngoscope, 128:1663-1667, 2018.

The Role of the Notch Signal Pathway in Mucosal Cell Metaplasia in Mouse Acute Otitis Media

Otitis media (OM) is a major cause of morbidity in pediatric and adult patients. This inflammatory condition is characterized by mucous cell hyperplasia that is thought to produce mucins from the middle ear mucosa. We are interested in the role of Notch signalling pathway in this inflammatory process. Using an acute otitis media (AOM) mouse model through injection of Streptococcus Pneumoniae into the middle ear, histopathologic examination and quantitative RT-PCR, acute inflammation with the thickness of mucosa, Goblet cell hyperplasia, and cilia loss were determined and gene expression related to the Notch signaling pathway were evaluated. Upregulation of the mucous cell markers, Argr2 and Muc5AC, and downregulation of the cilia cell marker, Foxj1 and Dnai2, were observed in AOM. In addition, genes encoding Notch receptors and ligands (Notch1, Notch2, Notch3, Notch4 and Dll1) and the Notch target genes (Hes1, Hes5, Hey1, NRARP) in AOM decreased significantly. The expression of the Notch1 and Jagged1 also showed down-regulation throughout the mouse middle ear epithelium. Taken together, this study suggests that downregulation of the Notch signaling pathway is involved in the mucosa hyperplasia during AOM.

The development and functions of multiciliated epithelia

Multiciliated cells are epithelial cells that are in contact with bodily fluids and are required for the proper function of major organs including the brain, the respiratory system and the reproductive tracts. Their multiple motile cilia beat unidirectionally to remove particles of external origin from their surface and/or drive cells or fluids into the lumen of the organs. Multiciliated cells in the brain are produced once, almost exclusively during embryonic development, whereas in respiratory tracts and oviducts they regenerate throughout life. In this Review, we provide a cell-to-organ overview of multiciliated cells and highlight recent studies that have greatly increased our understanding of the mechanisms driving the development and function of these cells in vertebrates. We discuss cell fate determination and differentiation of multiciliated cells, and provide a comprehensive account of their locations and functions in mammals.

Middle ear mucosal regeneration by tissue-engineered cell sheet transplantation

The recurrence of cholesteatoma after surgical treatment often occurs as a result of poor mucosal regeneration in the middle ear cavity and mastoid cavity and changes, such as granulation tissue formation, which impair gas exchange in the middle ear cavity. Conventional tympanoplasty often results in a lack of mucosal regeneration in the resected area of the mastoid cavity. In particular, mucosal regeneration in a poorly pneumatized mastoid cavity is extremely difficult. If the middle ear mucosa can be preserved or rapid postoperative regeneration of mucosa on the exposed bone surface can be achieved after middle ear surgery, the results of surgical treatment for otitis media, including cholesteatoma, can potentially be improved and the physiological function of the middle ear can be recovered. To overcome these limitations, we developed a novel treatment method combining tympanoplasty and autologous nasal mucosal epithelial cell sheet transplantation for postoperative regeneration of the middle ear mucosa. In clinical research, we endoscopically removed an approximately 10 × 10 mm2 piece of nasal mucosal tissue. Tissue-engineered autologous nasal mucosal epithelial cell sheets were fabricated by culturing the harvested cells in an aseptic environment in a good manufacturing practice-compliant cell processing facility. The cultivated cell sheets were transplanted, during tympanoplasty, onto the exposed bony surface of the attic of the tympanic and mastoid cavities where the mucosa had been lost. We performed this procedure on four patients with middle ear cholesteatoma and one patient with adhesive otitis media. All patients showed favorable postoperative course with no adverse events or complications and the patients' hearing ability post-transplantation remained good.

Preoperative steroids for hearing preservation cochlear implantation: A review

Preoperative steroids have been shown to be beneficial in reducing the hearing loss associated with cochlear implantation. This review article discusses the mechanism of action, effects of differing routes of administration, and side effects of steroids administered to the inner ear. Studies on the role of preoperative steroids in animal and human studies are also examined and future directions for research in this area are discussed.

Determination of the glycosylation-pattern of the middle ear mucosa in guinea pigs

In the present study the glycosylation pattern of the middle ear mucosa (MEM) of guinea pigs, an approved model for middle ear research, was characterized with the purpose to identify bioadhesive ligands which might prolong the contact time of drug delivery systems with the middle ear mucosa (MEM). To assess the utility of five fluorescein labeled plant lectins with different carbohydrate specificities as bioadhesive ligands, viable MEM specimens were incubated at 4°C and the lectin binding capacities were calculated from the MEM-associated relative fluorescence intensities. Among all lectins under investigation, fluorescein-labeled wheat germ agglutinin (F-WGA) emerged as the highest bioadhesive lectin. In general, the accessibility of carbohydrate moieties of the MEM followed the order: sialic acid and N-acetyl-d-glucosamine (WGA)>>mannose and galactosamine (Lensculinaris agglutinin)>N-acetyl-d-glucosamine (Solanumtuberosum agglutinin)>fucose (Ulexeuropaeus isoagglutinin I)>>terminal mannose α-(1,3)-mannose (Galanthusnivalis agglutinin). Competitive inhibition studies with the corresponding carbohydrate revealed that F-WGA-binding was inhibited up to 90% confirming specificity of the F-WGA-MEM interaction. The cilia of the MEM were identified as F-WGA binding sites by fluorescence imaging as well as a z-stack of overlays of transmission, F-WGA- and nuclei-stained images of the MEM. Additionally, co-localisation experiments revealed that F-WGA bound to acidic mucopolysaccharides of the MEM. All in all, lectin-mediated bioadhesion to the MEM is proposed as a new concept for drug delivery to prolong the residence time of the drug in the tympanic cavity especially for successful therapy for difficult-to-treat diseases such as otitis media.

Autologous human nasal epithelial cell sheet using temperature-responsive culture insert for transplantation after middle ear surgery

Postoperative mucosal regeneration of the middle ear cavity and the mastoid cavity is of great importance after middle ear surgery. However, the epithelialization of the mucosa in the middle ear is retarded because chronic inflammation without epithelialization aggravates gas exchange and clinical function. These environmental conditions in the middle ear lead to postoperative retraction and adhesion of the newly-formed tympanic membrane. Therefore, if the mucosa on the exposed middle ear bone surface can be rapidly regenerated after surgery, the surgical treatments for cholesteatoma and adhesive middle ear disease can potentially be improved. In this study, we successfully generated a cell sheet designed for the postoperative treatment of cholesteatoma. We used nasal cells to create an artificial middle ear mucosal cell sheet with a three-dimensional (3D) configuration similar to that of the middle ear mucosa. The sheets consisted of multi-layered mucosal epithelia and lower connective tissue and were similar to normal middle ear mucosa. This result indicates that tissue-engineered mucosal cell sheets would be useful to minimize complications after surgical operations in the middle ear and future clinical applications are expected. Copyright © 2015 John Wiley & Sons, Ltd.

The effect of transplantation of nasal mucosal epithelial cell sheets after middle ear surgery in a rabbit model

Postoperative regeneration of the middle ear mucosa and pneumatization of the middle ear cavity are of great importance after middle ear surgery. This study developed a new method to transplant autologous nasal mucosal epithelial cell sheets into the damaged middle ear cavity. The aim of this study was to evaluate postoperative healing after the transplantation of the cell sheets. Rabbit nasal mucosal epithelial cell sheets were fabricated on a temperature-responsive culture dish, and transplanted into the damaged middle ear of rabbit, which was surgically created. The healing of middle ears was evaluated by histology and X-ray computed tomography after transplantation. Functional evaluation was performed by measuring the maximum middle ear total pressure reflecting a trans-mucosal gas exchange function. Two control groups were used: the normal control group and the mucosa-eliminated control group. Transplantation of cell sheets suppressed the bone hyperplasia and the narrowing of pneumatic space in the middle ear cavity compared with the mucosa-eliminated control group. The mucosal gas exchange function was also better in the cell sheet-transplanted group. Nasal mucosal epithelial cell sheet was confirmed to be useful as an effective graft material after middle ear surgery and hopefully become a novel therapy in the future.

Middle ear mucosal regeneration with three-dimensionally tissue-engineered autologous middle ear cell sheets in rabbit model

The likelihood of recurrent retraction and adhesion of newly formed tympanic membrane is high when middle ear mucosa is extensively lost during cholesteatoma and adhesive otitis media surgery. If rapid postoperative regeneration of the mucosa on the exposed bone surface can be achieved, prevention of recurrent eardrum adhesion and cholesteatoma formation, for which there has been no definitive treatment, can be expected. Suture-less transplantation of tissue-engineered mucosal cell sheets was examined immediately after the operation of otitis media surgery in order to quickly regenerate middle ear mucosa lost during surgery in a rabbit model. Transplantable middle ear mucosal cell sheets with a three-dimensional tissue architecture very similar to native middle ear mucosa were fabricated from middle ear mucosal tissue fragments obtained in an autologous manner from middle ear bulla on temperature-responsive culture surfaces. Immediately after the mucosa was resected from middle ear bone bulla inner cavity, mucosal cell sheets were grafted at the resected site. Both bone hyperplasia and granulation tissue formation were inhibited and early mucosal regeneration was observed in the cell sheet-grafted group, compared with the control group in which only mucosal removal was carried out and the bone surface exposed. This result indicates that tissue engineered mucosal cell sheets would be useful to minimize complications after the surgical operation on otitis media and future clinical application is expected.

Mcph1-deficient mice reveal a role for MCPH1 in otitis media

Otitis media is a common reason for hearing loss, especially in children. Otitis media is a multifactorial disease and environmental factors, anatomic dysmorphology and genetic predisposition can all contribute to its pathogenesis. However, the reasons for the variable susceptibility to otitis media are elusive. MCPH1 mutations cause primary microcephaly in humans. So far, no hearing impairment has been reported either in the MCPH1 patients or mouse models with Mcph1 deficiency. In this study, Mcph1-deficient (Mcph1^tm1a/tm1a) mice were produced using embryonic stem cells with a targeted mutation by the Sanger Institute's Mouse Genetics Project. Auditory brainstem response measurements revealed that Mcph1^tm1a/tm1a mice had mild to moderate hearing impairment with around 70% penetrance. We found otitis media with effusion in the hearing-impaired Mcph1^tm1a/tm1a mice by anatomic and histological examinations. Expression of Mcph1 in the epithelial cells of middle ear cavities supported its involvement in the development of otitis media. Other defects of Mcph1^tm1a/tm1a mice included small skull sizes, increased micronuclei in red blood cells, increased B cells and ocular abnormalities. These findings not only recapitulated the defects found in other Mcph1-deficient mice or MCPH1 patients, but also revealed an unexpected phenotype, otitis media with hearing impairment, which suggests Mcph1 is a new gene underlying genetic predisposition to otitis media.

[Attic exposure-antrum exclusion as an on demand surgical technique for cholesteatoma]

INTRODUCTION AND OBJECTIVE

Attic exposure and antrum exclusion (AE-AE) is an on demand surgical technique for the treatment of cholesteatoma. Several techniques have been described with variable recurrence rates. The aim of the study was to describe this surgical technique and its indications and to analyse long-term outcomes.

MATERIALS AND METHODS

Forty-two patients were included. They received AE-AE in a tertiary centre and were followed-up from 6 months to 7 years. The surgical technique exposes the attic by drilling the superior wall of the external auditory canal and excludes the antrum and the mastoid cells by closing the aditus with a cartilage graft. It is indicated if the lesion does not go beyond the aditus or, if it does, it is a delimited cholesteatoma not damaging the labyrinth. The patients were followed-up by physical examination and radiology (CT scan and Non-EPI diffusion-weighted MRI since 2009).

RESULTS

The recurrence rate of the cholesteatoma was 4.8%. At recurrence, an open canal-wall-down mastoidectomy technique was performed. The rate of otorrhea (2/42 cases), serous otitis (2/42) and other complications was low, so aquatic activities were not contraindicated. The AE-AE did not modify ossicular chain reconstruction with respect to the rest of surgical techniques.

CONCLUSIONS

AE-AE is a canal-wall-down technique. Its purpose is to remove the lesion and to reduce the recurrence of cholesteatoma. In addition, it allows the entrance of water and reduces the need for 2(nd) look surgery. Non-EPI diffusion-weighted MRI is a reliable technique for follow-up, especially for the excluded mastoid.

Hualuronic acid in secretory otitis media

Middle-ear effusions of the mucoid type were collected from 14 children with secretory otitis media and analysed by a sensitive assay for hyaluronic acid. The concentration of the polysaccharide varied between three and 42 μg/g. in different patients but was in the same range in effusion material taken from the two ears of the same patient. As the hyaluronic acid concentrations were high compared to the serum levels, the results indicate that the effusion material contains a component derived from connective tissue.

The effect of changes in ambient oxygen concentration on the bioelectric properties of middle ear mucosa

The purpose of the present study was to compare the effect of 24 h of exposure to 7% O2 (normal middle ear physiological conditions) vs. 21% O2 (found in the middle ear after ventilation tube placement) on transepithelial Na+ absorption and Cl- secretion in cultured gerbil middle ear epithelial cell monolayers. Although no difference in apical Na+ absorption was identified, the UTP-induced stimulation of apical Cl- secretion in the presence of apical Na+ channel blockade with amiloride was significantly enhanced after exposure to 21% O2 compared with 7% O2 exposure. In the presence of a calcium-activated Cl- channel inhibitor, DIDS, UTP-induced stimulation of Cl- secretion after 21% O2 exposure was decreased, suggesting a role for calcium-activated Cl- channels in middle ear Cl- secretion in response to relative hyperoxia.

A case of carcinoid tumor of the middle ear

We report here a case of a carcinoid tumor observed in the middle ear (ME), which was initially diagnosed as ME adenoma. The patient was a 64-year-old woman who was first seen in our hospital in March 2001 for a 7-month hearing loss. On otoscopic examination, a whitish mass could be observed through the intact tympanic membrane. High-resolution computed tomography demonstrated a tumor-like lesion in the ME with no evidence of bone destruction. A myringotomy and biopsy were performed and an initial diagnosis of ME adenoma was made. Light microscopy showed fragments of cellular tissue in which both glandular (adenomatous) and trabecular (carcinoid) growth patterns could be identified, but neuroendocrine differentiation was not detected by immunohistochemistry (negative staining for chromogranin A and synaptophysin). On the basis of this diagnosis, the patient underwent a tympanomastoidectomy in June 2001, in which the presumed ME adenoma was completely excised and the diagnosis was modified to ME carcinoid tumor. Immunohistochemical examinations at that time showed positive staining of the tumor cells for chromogranin A and synaptophysin. This case suggests the difficulties in distinguishing ME carcinoid tumors from ME adenomas. The patient is without recurrence of her disease to date.

Middle ear adenoma with neuroendocrine differentiation

The lining of the middle ear cleft is normally a thin modified respiratory type mucosa. Normal mucosa of the middle ear is devoid of salivary type seromucous glands. Middle ear adenoma is a rare tumor that seems to be derived from the middle ear mucosa. This tumor has been previously described under a variety of names because of its different nature and biological behavior. We herein report a case of middle ear tumor that shows adenomatous and neuroendocrine features. A 64-year-old woman presented with a history of hearing loss, tinnitus and stuffy feeling of the right ear. The patient was treated two times for ear polyp. She finally underwent a tympanomastoidectomy and there was no evidence of recurrence 18 months after the procedure. Histopathological examination displayed cuboidal and columnar cells, arranged as glands, trabeculae and solid sheets. Neuroendocrine differentiation was revealed by immunohistochemical staining with polyclonal antibodies against neuron specific enolase and chromogranin antigens.

Culture of rabbit middle ear epithelial cells. A method for primary culture and subculture with identification, characterization and growth specification

During the last decade middle ear epithelium has been cultured from various species. Until now, subcultivation has been achieved only with the use of a feeder-cell layer or conditioned medium. These factors are possible confounders in the in vitro model. On the other hand, subcultivation is necessary for exact quantitative studies. We present a reproducible culture method allowing subcultivation without feeder-cells or conditioned medium. The main features in our method are a low-serum, hormone-supplemented medium, an incubation temperature of 34 degrees C, fixation of explants, gentle trypsinization and replating with high cell density. Cells were identified by immunohistochemistry through a battery of monclonal antibodies. The percentage of epithelial cells in the subculture was 99.2%. To our knowledge, this is the first report describing subcultivation of middle ear epithelial cells exclusively in a completely controlled environment. These are optimal circumstances for future investigation and quantification of various factors influencing proliferation and differentiation of middle ear epithelium.

Pathophysiology of middle ear epithelium: a new role for prostaglandin E2

INTRODUCTION

Otitis media with effusion is a disease of the middle ear epithelium resulting from a decreased sol layer as well as increased mucus secretion and plasma-derived protein transudation, which causes mucus plugging. Because the epithelium keeps the middle ear cavities fluid-free and air-filled, we investigated its fluid transport capacities, which may be involved in both efficacy of the mucociliary clearance and drying-out of the posterior ear cavities (Yen PT et al: Acta Otolaryngol (Stockh) 113, 1993). We have established the absorptive capacity of middle ear epithelial cells in primary culture (Herman P, et al: Am J Physiol 262, 1992). However, the paucity of cells obtained by enzymatic digestion led us to develop a new model for further investigation of middle ear epithelial cell.

METHODS

We established a middle ear cell line (MESV) using simian virus 40 (SV40) infection of middle ear epithelial cells from the Mongolian gerbil.

RESULTS

Investigation of the transport processes using the short-circuit current technique showed that MESV cells retain most characteristics of the original middle ear epithelial cells. Transepithelial sodium transport from the apical to the basal side was responsible for the transepithelial lumen-negative potential difference.

CONCLUSION

The presence of high concentrations of prostaglandin E2 in the middle ear effusions has been documented. This work investigates the effect of prostaglandin E2 on the rate of transepithelial ion transport of MESV cells. Prostaglandin E2 increased the rate of electrogenic sodium transport by means of increase in the intracellular cyclic adenosine monophosphate (cAMP) content. Such a modulation of sodium transport in the course of otitis media could be responsible for the reduced periciliary sol layer that impairs the mucociliary clearance.

Middle ear cell line that maintains vectorial electrolyte transport

The middle ear epithelium plays a major role in keeping the temporal bone cavities fluid-free and air-filled, which is a mandatory condition to allow optimum transmission of the sound vibrations from the tympanic membrane to the inner ear. Previous works have recently established the absorptive function of the middle ear epithelium, using primary cultures derived from Mongolian gerbil (Meriones unguiculatus). Because of the paucity of cells as obtained by enzymatic digestion, we developed a middle ear cell line (MESV) using wild-type SV40 infection of primary culture of Mongolian gerbil's middle ear epithelial cells. Transformation was attested by nuclear expression of SV40 large T antigen, prolonged in vitro passages (presently beyond 50 passages), and tumor-inducing ability when subcutaneously injected in athymic mice. Transport properties were evaluated after the fifteenth passage. MESV cells retained most cardinal properties of the original middle ear epithelial cells: cell polarization was evidenced by the presence of mature junctional complexes that separate the cell membrane in two distinct domains, with apical microvilli at the luminal side, and by vectorial sodium transport responsible for the transepithelial lumen-negative potential difference (-9.3 +/- 0.14 mV in culture conditions (n = 9), -2.1 +/- 0.25 mV after overnight growth factors and serum deprivation). Short-circuit current was, like in primary cultures, mainly related to a sodium transport occurring through amiloride-sensitive apical sodium channels, since apical addition of amiloride (10(-5) M) reduced ISC from 7.0 +/- 1.4 to 0.6 +/- 0.1 microA/cm2 (P < 0.01, n = 6). Cellular cAMP content was increased by isoproterenol and prostaglandin E2 from 40.5 +/- 5.6 to 258.5 +/- 17.3 and 55.6 +/- 6.2 pmol/mg protein per 5 min, respectively (P < 0.05, n = 10). Isoproterenol and prostaglandin E2 increased ISC with very similar maximal effects: isoproterenol (10(-4) M) increased ISC from 5.73 +/- 0.31 to 12.77 +/- 0.39 microA/cm2, while prostaglandin E2 increased ISC from 5.47 +/- 0.21 to 12.87 +/- 0.42 (n = 3). Since amiloride (10(-5) M) abolished this stimulation, this may be related to an increase of the electrogenic sodium transepithelial transport. The MESV cell line could provide an interesting tool as a model of middle ear epithelial cells for the study of pathophysiological modulations of ion transport.

Culture of middle ear epithelium: a review

We discuss several techniques of culturing middle ear epithelium from several species, which was formerly difficult but is now possible because of recent advances in culture methods. The three main methods of initiating a culture are organ culture, primary explant culture, and cell culture. Although each method has both advantages and disadvantages, investigators can choose the method most suitable to their purpose. A few researchers, including ourselves, have succeeded in obtaining serial culture of middle ear epithelium. Using 3T3 feeder layer technique or conditioned medium enabled us to develop a fibroblast-free cultured middle ear epithelium. The availability of cultured middle ear epithelium provides a potential tool in future middle ear research.

Effects of irradiation on the ciliary activity of the eustachian tube and the middle ear mucosa

Radiation-induced changes in the ciliary activity of the eustachian tube and middle ear mucosa were investigated in a laboratory model. Twenty-four guinea pigs were sacrificed, and a mucosa at the bony portion of each eustachian tube and from the middle ear proximal and distal to the tube were sampled. The mucosal samples were irradiated with 200 kV hard X-rays discretely at a dosage level of 0.5-30.0 Gy, and the induced changes in ciliary activity were expressed as a percent deviation from baseline levels before irradiation. The present study demonstrates that the cilia of the eustachian tube and middle ear mucosa show different reactions to irradiation according to their tympanic locations.