Predictive factors of acute sensorineural hearing loss in adult Japanese patients for clinical application by primary care doctors: a cross-sectional study

Background

Several methods are used for hearing loss screening; however, their benefits are uncertain. In this study, we aimed to determine the predictive factors of acute sensorineural hearing loss for clinical application by primary care doctors.

Methods

This retrospective, cross-sectional study included 365 patients with acute sensorineural hearing loss without prior therapy. The patients’ clinical data, demographic information, and medical histories were obtained, and they were asked about comorbidities. In addition, we assessed lifestyle factors such as stress level, alcohol consumption, marital status, and socioeconomic level. Logistic regression analysis was performed to investigate the diagnostic predictive ability of the selected factors associated with acute sensorineural hearing loss. The hearing levels of all patients were evaluated using pure tone audiometry.

Results

We identified significant predictive factors for acute sensorineural hearing loss. The absence of hyperacusis was a predictive factor for sudden sensorineural hearing loss. Younger age, female sex, and marital status were predictive factors for acute low-tone hearing loss. High body mass index, high socioeconomic level, low alcohol consumption, high stress level, hyperacusis, and vertigo/dizziness were predictive factors for Ménière’s disease. High body mass index and ear fullness were predictive factors for perilymph fistula. Low stress level was a predictive factor for acoustic tumours.

Conclusions

Our findings can be used to distinguish between the types of acute sensorineural hearing loss. Symptoms, physical status, and lifestyle factors identified during this study are useful markers for predicting acute sensorineural hearing loss occurrence.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12875-022-01830-8.

Temporal virtual reality-guided, dual-task, trunk balance training in a sitting position improves persistent postural-perceptual dizziness: proof of concept

Background

Persistent postural-perceptual dizziness (PPPD) is a newly defined disorder characterized by functional dizziness. Due to its recent discovery, definitive treatment for PPPD has not been established; therefore, this study aimed to assess the effectiveness of virtual reality (VR)-guided, dual-task, trunk balance training for the management of PPPD using the mediVR KAGURA system.

Methods

We analyzed data of patients who presented with PPPD from January 1, 2021, to February 28, 2021. The VR group included patients who underwent mediVR KAGURA-guided training for 100 tasks (10 min). Patients with PPPD who received standard treatment and rehabilitation were assigned to the control group. Equilibrium tests were performed at baseline and immediately after mediVR KAGURA-guided training to examine its effectiveness in improving static and dynamic balance. Additionally, clinical questionnaires related to balance disorders were administered at baseline and 1 week after mediVR KAGURA-guided training to examine its effects on balance-related symptoms. The primary outcome was improvements in static and dynamic balance and Niigata PPPD Questionnaire (NPQ) scores.

Results

VR-guided training using mediVR KAGURA improved objective outcomes, including static and dynamic postural stability, after a single 10-min training session. Additionally, mediVR KAGURA-guided training improved scores on the Hospital Anxiety and Depression Scale and NPQ 1 week after the 10-min training session.

Conclusion

VR-guided training using mediVR KAGURA represents a viable method for managing balancing ability, anxiety, and symptoms in patients with PPPD. Such training provides a safe and cost-effective solution for PPPD management. Further studies are required to evaluate the clinical efficacy of this strategy.

Trial registration: Institutional Ethics Committee of Kitano Hospital, approval number: 1911003. Registered 18 December 2019, https://kitano.bvits.com/rinri/publish_document.aspx?ID=426.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12984-022-01068-6.

Effects of Kampo medicine hangebyakujutsutemmato on persistent postural-perceptual dizziness: A retrospective pilot study

BACKGROUND

Persistent postural-perceptual dizziness (PPPD) is a functional disorder, typically preceded by acute vestibular disorders. It is characterized by a shift in processing spatial orientation information, to favor visual over vestibular and somatosensory inputs, and a failure of higher cortical mechanisms. To date, no therapies for PPPD have been approved. Kampo medicine hangebyakujutsutemmato (HBT) has been reported to alleviate disturbances of equilibrium. We hypothesized that HBT would be a beneficial treatment for PPPD.

AIM

To examine the efficacy of HBT for the treatment of PPPD.

METHODS

Patients with PPPD were enrolled and divided into two groups: The HBT group (n = 24) and the non-HBT group (n = 14). The participants completed questionnaire surveys [Niigata PPPD questionnaire (NPQ), dizziness handicap inventory, hospital anxiety and depression scale (HADS), orthostatic dysregulation questionnaire, pittsburg sleep quality index (PSQI), and motion sickness scores] before and after HBT treatment. Additionally, to identify HBT responders, multivariate regression analysis was performed using the results of the questionnaire surveys and equilibrium tests; including stabilometry, and caloric, vestibular evoked myogenic response, and head-up tilt tests.

RESULTS

Thirty-eight outpatients were included in this study, of which 14 patients (3 men, 11 women; mean age, 63.5 ± 15.9 years) received treatment without HBT, and 24 (1 man, 23 women; mean age, 58.2 ± 18.7 years) received combination treatment with HBT. Following HBT treatment, NPQ scores decreased significantly (baseline 40.1 ± 10.0 vs 2 mo 24.6 ± 17.7, P < 0.001). No statistically significant changes were observed in the NPQ scores in the non-HBT group (baseline 38.6 ± 12.2 vs 2 mo 39.4 ± 14.4, P = 0.92). Multivariable regression analysis revealed that the results of stabilometry (P = 0.02) and the caloric (P = 0.03), and head-up tilt tests (P < 0.001), HADS (P = 0.003), and PSQI (P = 0.01) were associated with HBT responsiveness in PPPD patients.

CONCLUSION

HBT may be an effective adjunct therapy for PPPD. Patients with autonomic dysfunction, unstable balance, semicircular canal paresis, anxiety, and poor sleep quality may be high responders to HBT.

Diagnosis of Spontaneous Cerebrospinal Fluid Rhinorrhea Using Thin-Slice Computed Tomographic Images With Multiplanar Reconstruction and Three-Dimensional Virtual View Endoscopy

Spontaneous cerebrospinal fluid (CSF) rhinorrhea represents an important clinical entity, which is associated with elevated intracranial pressure and is rarely treated successfully without surgical intervention. Here we report a case of spontaneous CSF rhinorrhea. The patient was a 54-year-old male, who presented with bacterial meningitis and was referred to the Department of Otorhinolaryngology for a detailed examination of the nose and sinuses. Reconstructed thin-slice computed tomography (CT) revealed multiple fistulae on the clivus. The defect was successfully repaired by transnasal endoscopic surgery, with the assistance of virtual endoscopic images, which were created by the surgical planning and navigation system from thin-slice CT images. This incremental improvement in the imaging technique helped with the diagnosis and surgical treatment of CSF rhinorrhea.

Regenerative Medicine of the Trachea: The First Human Case

Objectives:

The objective of the present study was to demonstrate regenerative medicine of the tracheal tissue by using an in situ tissue engineering technique for airway reconstruction.

Methods:

Based on the previous successful experimental animal studies, the current regenerative technique was applied to repair of the trachea of a 78-year-old woman with thyroid cancer. A Marlex mesh tube covered by collagen sponge was used as a tissue scaffold. The operative intervention included right hemithyroidectomy, resection of the trachea, and tracheoplasty using the scaffold. The right half of three rings of the trachea was resected, and the scaffold material was sutured to the defect of the trachea.

Results:

After 2 weeks, the mesh collagen structure of the artificial material could be seen with endoscopy in most of the implanted area. The artificial material was covered with epithelial growth after 2 months. Epithelialization continued to cover the artificial material completely for 2 years without any complications.

Conclusions:

The current regenerative technique avoided tracheotomy, a second operation, and deformity. Good epithelialization has been observed on the tracheal luminal surface without any complications for 2 years. Although long-term observation is required, regenerative medicine of the tracheal tissue appears feasible for airway reconstruction.

Tissue Engineering for Regeneration of the Tracheal Epithelium

Objectives:

The slowness of epithelialization on the artificial trachea that has been successfully used in humans is a problem. The purpose of this study was to develop a way to regenerate the epithelium on the surface of this artificial trachea.

Methods:

In an in vitro study, isolated rat tracheal epithelial cells were seeded on a collagenous gel that was stratified on a collagenous sponge. Histologic and immunohistochemical examinations were made. In an in vivo study, we transplanted grafts with green fluorescent protein–positive tracheal epithelial cells onto the tracheal defects of normal rats. At 3, 7, 14, and 30 days after the operation, histologic and immunohistochemical examinations were made.

Results:

In the in vitro study, the 3 layers — the epithelium, gel, and sponge — could be observed. The epithelium expressed cytokeratin 14, cytokeratin 18, and occludin. In the in vivo study, the artificial trachea was covered with epithelium at 3 days after operation, and then the epithelium differentiated from single- or double-stratified squamous epithelium into columnar ciliated epithelium. Green fluorescent protein–positive cells were found 3 days after operation.

Conclusions:

We believe that the method used in our experiment is an effective way to regenerate the epithelium on the surface of an artificial trachea. With further experimentation, this method should be suitable for clinical application.

Cricoid Regeneration Using in Situ Tissue Engineering in Canine Larynx for the Treatment of Subglottic Stenosis

The purpose of the present study was to evaluate the efficacy of cricoid regeneration via in situ tissue engineering in a canine larynx for the treatment of subglottic stenosis. As the tissue scaffold, a Marlex mesh tube coated by collagen sponge was used for a rigid airway framework and for tissue regrowth around the tube. On 5 dogs, the larynx was exposed and the anterior third of the cricoid cartilage was resected. The tube was anastomosed to the lower edge of the thyroid cartilage and to the first tracheal cartilage. By postoperative endoscopic examination at 3 to 7 months, no airway obstruction was observed in any of the dogs. There was granulation tissue in 2 dogs and slight mesh exposure in 1 dog, but they were asymptomatic. Confluent regeneration of the epithelium over the scaffold and good incorporation of the scaffold mesh into the host tissue were observed after surgery.

Adipose-derived stem cells versus bone marrow-derived stem cells for vocal fold regeneration

OBJECTIVES/HYPOTHESIS

Vocal fold scarring presents therapeutic challenges. Recently, cell therapy with mesenchymal stromal cells has become a promising approach. The aim of this study was to compare the therapeutic potential of adipose-derived stem cells (ASC) with bone marrow-derived stem cells (BMSC) for vocal fold regeneration.

STUDY DESIGN

Prospective animal experiments with controls.

METHODS

The vocal folds of Sprague-Dawley rats were unilaterally injured. Two months after injury, rats were treated with a local injection of ASC (ASC group), BMSC (BMSC group), or saline (sham-treated group). The GFP-labeled ASC and BMSC were extracted from CAG-EGFP rats. Larynges were harvested for histological and immunohistochemical examinations 1 and 3 months posttransplantation and for quantitative real-time polymerase chain reaction (PCR) 1 month posttransplantation.

RESULTS

After 1 month, no surviving cells from the transplant were detected. Histological examination showed significantly increased hyaluronic acid (HA) and decreased dense collagen deposition in both ASC and BMSC groups compared to shams 1 and 3 months after treatment. Real-time PCR revealed that hyaluronan synthase 1 (Has1) and Has2 were upregulated in only the ASC group compared with the sham-treated group. Fibroblast growth factor 2 (basic) (Fgf2), hepatocyte growth factor (Hgf) and Has3 were upregulated in both cell transplantation groups. ASC seemed to upregulate Hgf more than did BMSC.

CONCLUSIONS

The regenerative effects of ASC and BMSC transplantation were found to be similar for the restoration. It is suggested that ASC might have more potential because of better recovery of HA, a superior antifibrotic effect, and the upregulation of Hgf.

LEVEL OF EVIDENCE

N/A.

Pharmacokinetics and safety of human recombinant hepatocyte growth factor administered to vocal folds

OBJECTIVES/HYPOTHESIS

Previous animal studies demonstrated that hepatocyte growth factor (HGF) has the potential to regenerate scarred vocal folds. In addition, HGF is now produced under a good manufacturing practice (GMP) procedure. Therefore, human clinical trials of HGF are warranted in patients with vocal fold scarring. In the current study, we investigated the pharmacokinetics and the local tissue responses of HGF administered to rat vocal folds.

STUDY DESIGN

Prospective animal experiment.

METHODS

Five μg of recombinant human HGF was administered to the vocal folds of Sprague-Dawley rats (n = 60) using a microsyringe. The concentration of HGF in larynges and blood was investigated by enzyme-linked immunosorbent assay. To evaluate the local tissue responses caused by HGF administration, endoscopic and histological examinations were performed.

RESULTS

HGF concentration in the larynges was 50.1 μg/g tissue 5 minutes after administration. The concentration decreased rapidly to 1.71 μg/g tissue at 12 hours after administration and to 0.29 ng/g tissue at 24 hours after administration. Seven days after administration, HGF concentration was minimal in one-half of the cases and was not detected in the other cases. Transmission of HGF to blood was detected in two of six cases at 5 minutes after administration, but was no longer detected 12 hours later. Endoscopic and histological examinations revealed no edema or erythema of the vocal folds in any of the cases.

CONCLUSIONS

The current results contribute to the safety and pharmacokinetic management of future clinical trials using HGF administered to vocal folds.

Restoration of scarred vocal folds using 5 amino acid-deleted type hepatocyte growth factor

OBJECTIVES/HYPOTHESIS

Our previous studies demonstrated a regenerative effect of recombinant human hepatocyte growth factor (HGF) on vocal fold scarring using full-length HGF. However, clinical application has not yet been achieved because of the lack of a good manufacturing practice (GMP) for full-length HGF. Another natural form of human HGF, 5 amino acid-deleted type HGF (dHGF), has been newly produced under a GMP procedure. In the current study, we investigated the effect of dHGF in comparison with full-length HGF for the treatment of vocal fold scars using a canine model.

STUDY DESIGN

Prospective animal experiment.

METHODS

The vocal folds of nine beagles were unilaterally injured. Four weeks after injury, the vocal folds were treated with an intracordal injection of full-length HGF (full HGF group), dHGF (dHGF group), or phosphate-buffered saline (sham group). Vibratory and histological examinations were performed for each group 6 months after injury.

RESULTS

Vibratory examinations demonstrated significantly lower phonation threshold pressure and a higher ratio of normalized mucosal wave amplitude in both the full HGF and dHGF groups as compared to the sham group. Histological examination showed restoration of hyaluronic acid in both the full HGF and dHGF groups as compared to the sham group. No significant differences were observed for each parameter between the full HGF group and the dHGF group.

CONCLUSIONS

dHGF showed the same potential for regenerative effects on vocal fold scars as full-length HGF. dHGF should be applicable for human clinical trials in patients with vocal fold scars.

Effect of astaxanthin on vocal fold wound healing

OBJECTIVES/HYPOTHESIS

Our previous study demonstrated that a large amount of reactive oxygen species (ROS) is produced during the early phase of vocal fold wound healing. In the current study, we investigated the effect of astaxanthin, which is a strong antioxidant, on the regulation of oxidative stress and scarring during vocal fold wound healing.

STUDY DESIGN

Prospective animal experiment with control.

METHODS

Sprague-Dawley rats were dosed with astaxanthin (Ast-treated group, 100 mg/kg/day) or olive oil (sham-treated group) by oral gavage daily from preinjury day 1 to postinjury day 4. After vocal folds were injured under the endoscope, larynges were harvested for histological and immunohistochemical examinations on postinjury days 1, 3, 5, and 56, and quantitative real time polymerase chain reaction (PCR) on postinjury days 1 and 3.

RESULTS

The expression of 4-hydroxy-2-nonenal, which is an oxidative stress marker, was reduced significantly in the lamina propria of the Ast-treated group as compared to the sham-treated group. Histological examination showed significantly less tissue contraction with favorable deposition of hyaluronic acid in the lamina propria of the Ast-treated group compared to the sham-treated group. Real time PCR revealed significantly upregulated mRNA expression of basic fibroblast growth factor on postinjury day 1 and procollagen type I in the Ast-treated group compared to the sham-treated group.

CONCLUSIONS

These findings suggest that astaxanthin has the potential to prevent vocal fold scarring by regulating oxidative stress during the early phase of vocal fold wound healing.

Functional regeneration of laryngeal muscle using bone marrow-derived stromal cells

OBJECTIVES/HYPOTHESIS

To investigate the functional efficiency of skeletal muscles regenerated by transplantation of bone marrow-derived stromal cells (BSCs) or induced-muscle progenitor cells (IMCs) as assessed in the canine posterior cricoarytenoid (PCA) muscle injury model.

STUDY DESIGN

Prospective animal experiment with control.

METHODS

We performed BSC/IMC transplantation into injured canine PCA muscles. We investigated the capability of auto- and allo-BSC/IMC transplantation using a gelatin sponge scaffold to promote functional regeneration of PCA muscles. Transplantation was assessed by fiberscopic analysis of vocal fold movement. We also examined the histologic changes of the transplanted regions. As a control, a gelatin sponge scaffold without additional cells was transplanted into the injured area.

RESULTS

Auto-BSC/IMC transplantation effectively restored vocal fold movement, whereas scaffold alone or allo-BSC/IMC transplantation did not. Histologic examination revealed that (in cases of good recovery) muscle regeneration occurred in the area of cell transplantation, and scar formation without muscle regeneration was observed under control conditions. The dogs with autologous transplantation of BSC had faster functional recovery than did dogs treated with autologous transplantation of IMC.

CONCLUSIONS

Functional efficiency was shown in skeletal muscles regenerated using BSCs and IMPs. Motor function recovery was observed using autologous transplantation of BSCs and IMCs. Minimal functional recovery was observed using allogeneic transplantation of these cells.

Improvement of eustachian tube function by tissue-engineered regeneration of mastoid air cells

Objectives/Hypothesis

Most cases of chronic otitis media (OMC) are associated with poor development of the mastoid air cells (MACs) and poor Eustachian tube (ET) function. We have previously reported that MAC regeneration can effectively eliminate intractable OMC. In this study, we assessed the ability of regenerated MACs to restore normal gas exchange function and contribute to improved ET function.

Study Design

Clinical trial with control.

Setting

General hospitals.

Materials and Methods

Seventy-six patients with OMC, including cholesteatoma and adhesive otitis media, received tympanoplasty and MAC regeneration therapy. At the first-stage of tympanoplasty, artificial pneumatic bones and/or autologous bone fragments were implanted into the opened mastoid cavity. At the 2nd-stage operation, a nitrous oxide (N2O) gas study was performed in 10 patients to measure middle ear pressure (MEP). For the control group, MEP was measured in five patients with good MAC development during cochlear implantation or facial nerve decompression. ET function was measured twice in each patient, once before the 1st operation and 6 months after the second operation.

Results

At the 2nd-stage operation, in all cases with regenerated MACs and in the normal control group, MEP changed after administration of N2O. In contrast, no change in MEP was observed in cases with unregenerated MACs. In 70% (n = 37/53) of the regenerated MAC group, ET function was improved, whereas improvement of ET function was observed in only 13% (n = 3/23) of the unregenerated MAC group.

Conclusions

Tissue-engineered regeneration of MACs improves ET function and gas exchange in the middle ear. Laryngoscope, 2012

Level of Evidence

3b

Transforming growth factor β3 for the prevention of vocal fold scarring

OBJECTIVES/HYPOTHESIS

Vocal fold scarring poses a therapeutic challenge. It causes hoarseness and decreases the quality of life. Transforming growth factor β3 (TGFβ3) is highly expressed in fetal wounds that heal without scarring, and administration of TGFβ3 has been reported to prevent scarring of the skin and the buccal mucosa. Thus TGFβ3 is considered to be a key molecule in scar-free healing. This study aimed to examine the ability of TGFβ3 to prevent vocal fold scarring, with particular attention paid to the distribution of extracellular matrices and functional outcomes.

STUDY DESIGN

Prospective study using an animal model.

METHODS

Ten beagles were used in this study; 500 μL of TGFβ3 (0.5 μg/mL: 5 beagles) or saline (5 beagles) was injected into the vocal fold lamina propria. Fifteen minutes after injection, vocal folds were injured by stripping off the entire layer of the lamina propria. Six months after surgery, animals were euthanized and the larynges were harvested. Vibratory and histologic examinations were performed.

RESULTS

The administration of TGFβ3 suppressed granulation-tissue formation and scarring. TGFβ3-treated vocal folds showed significantly better vibratory properties, resembling normal vocal folds. Histologic analysis revealed favorable restoration of elastin and hyaluronic acid in the lamina propria. The distribution of collagen was well organized, and collagen deposition was less dense in TGFβ3-treated vocal folds compared to sham-treated vocal folds.

CONCLUSIONS

Administration of TGFβ3 before injury significantly suppressed scar formation and induced favorable restoration of extracellular matrices in the vocal fold lamina propria, resulting in much improved phonatory function.

[Clinical outcomes cochlear reimplantation]

To clarify the clinical features of cochlear reimplantation and surgical changes in auditory performance, we retrospectively reviewed 10 of 252 cochlear implantation surgeries-6 adults and 4 children-among 129 children and 123 adults done between April 1987 and May 2009. Mean duration from initial implantation to reimplantation was 50.3 months in children and 89 months in adults, most commonly due to hard failure and implant exposure/infection (33%) in children and to hard failure (75%) in adults. The initial device implanted was the Nucleus multichannel implant (CI22M, CI24M, or CI24R). The second implant in 7 was the same or an upgrade of the same manufacturer's device, and in 2 children the HiRes 90K (Hifocus 1j) and in 1 adult the Clarion 1.2. Full initial and reinsertion succeeded in 8 cases but reinsertion proved difficult in 2 due to severe intracochlear granulation and osteoneogenseis. Auditory performance analyzed in 7 cases was mostly equal to or better than before reimplantation, although differences were not statistically significant. Reinsertion is rarely difficult, but electrode choice is important in preparing for difficult reinsertion. Post reinsertion auditory performance is satisfactory with some exceptions.

Tissue-engineered airway and "in situ tissue engineering"

Since the 1980s, tissue engineering has become one of the major areas of endeavor in medical research, applying the principles of biology and engineering to the development of functional substitutes for damaged tissue. Using this technology, various attempts have been made to create and apply a tissue-engineered prosthetic trachea, or airway. In addition to the conventional tissue engineering approach, a new substantially different concept has been advocated in Japan since 2000. This is "in situ tissue engineering," where a tissue is created not in vitro but in vivo, exploiting the potential of the living body for wound healing. An artificial trachea created by in situ tissue engineering has already been applied in human patients for reconstruction of airway defects, and promising results have been obtained. This article reviews recent progress in the relatively new field of airway reconstruction employing tissue engineering.

Glottal reconstruction with a tissue engineering technique using polypropylene mesh: a canine experiment

OBJECTIVES

The larynx must be resected in some cases of cancer or stenosis, and various techniques are generally employed to fill the resulting defect. No ideal way, however, has been established to restore vocal function after this form of insult. The aim of this preliminary feasibility study in a canine model was to investigate the effectiveness of a polypropylene-based tissue engineering approach to repair a partial glottal defect.

METHODS

Eight dogs were used in this study. A laryngeal defect involving resection of the left vocal fold was created through a thyroid cartilage window. A scaffold made of polypropylene and collagen was preclotted and wrapped with autologous fascia lata, inserted through the window, and sutured to the laryngeal defect in 5 dogs. The defect was reconstructed with an adjacent sternohyoid muscle flap in 3 control dogs. The surgical site was evaluated 3 months after operation by fiberscopic examination, computed tomographic imaging, histologic evaluation, and study of excised larynges.

RESULTS

On fiberscopic examination, the experimental group implants were completely covered with regenerated mucosa in all cases, and a favorable vocal fold contour was found in 4 of the 5 cases. One case was characterized by a concave vocal fold shape and red granulation. In the control group, the muscle flap was replaced by scarred mucosa with a concave vocal fold contour in 2 cases, and there was soft white granulation at the anterior resected edge in the third case. The histologic data revealed the regeneration of lined epithelium, subepithelial tissue, and muscle structure in both groups. The excised larynx phonatory data revealed reduced vibratory amplitude in the experimental group compared with the control group; however, excised phonation was not achieved in 2 of the 3 cases in the control group.

CONCLUSIONS

This polypropylene-based tissue engineering technique appears to be a viable tool for glottal reconstruction; however, additional refinement is required to maximize long-term phonatory function.

Atelocollagen sponge as a stem cell implantation scaffold for the treatment of scarred vocal folds

OBJECTIVES

Treatment of vocal fold scarring remains a therapeutic challenge. Our group previously reported the efficacy of treating injured vocal folds by implantation of bone marrow-derived stromal cells containing mesenchymal stem cells. Appropriate scaffolding is necessary for the stem cell implant to achieve optimal results. Terudermis is an atelocollagen sponge derived from calf dermis. It has large pores that permit cellular entry and is degraded in vivo. These characteristics suggest that this material may be a good candidate for use as scaffolding for implantation of cells. The present in vitro study investigated the feasibility of using Terudermis as such a scaffold.

METHODS

Bone marrow-derived stromal cells were obtained from GFP (green fluorescent protein) mouse femurs. The cells were seeded into Terudermis and incubated for 5 days. Their survival, proliferation, and expression of extracellular matrix were examined.

RESULTS

Bone marrow-derived stromal cells adhered to Terudermis and underwent significant proliferation. Immunohistochemical examination demonstrated that adherent cells were positive for expression of vimentin, desmin, fibronectin, and fspl and negative for beta III tubulin. These findings indicate that these cells were mesodermal cells and attached to the atelocollagen fibers biologically.

CONCLUSIONS

The data suggest that Terudermis may have potential as stem cell implantation scaffolding for the treatment of scarred vocal folds.

Effect of exogenous hepatocyte growth factor on vocal fold fibroblasts

OBJECTIVES

We have previously demonstrated the therapeutic potential of hepatocyte growth factor (HGF) in the treatment of vocal fold scarring, although how exogenous HGF affects gene expression of endogenous HGF or extracellular matrix components in the vocal fold fibroblasts remains unclear. In this in vitro study, we aimed to clarify this aspect in order to better understand the effects of HGF on the vocal folds.

METHODS

Fibroblasts were obtained from the lamina propria of the vocal folds of 5 Sprague-Dawley rats and were cultured with HGF at concentrations of 100, 10, 1, and 0 ng/mL. The cells were collected on days 1, 3, and 7, and the expression of endogenous HGF, its receptor c-Met, transforming growth factor-beta1 (TGF-beta1), procollagen types I and III, and hyaluronic acid synthase (HAS)-1 and HAS-2 messenger RNAs (mRNAs) was examined by real-time reverse transcription-polymerase chain reaction.

RESULTS

The expression of endogenous HGF and HAS-1 mRNAs increased significantly when exogenous HGF was administered at a concentration of 1 ng/mL. On day 1, the expression of TGF-beta1 and HAS-2 mRNAs increased significantly in response to 1 ng/mL HGF.

CONCLUSIONS

Exogenous HGF triggered the up-regulation of endogenous HGF, TGF-beta1, HAS-1, and HAS-2 mRNAs in vocal fold fibroblasts.

In situ tissue engineering for tracheal reconstruction using a luminar remodeling type of artificial trachea

BACKGROUND

After successful trials of tracheal reconstruction using mesh-type prostheses in canine models, the technique has been applied clinically to human patients since 2002. To enhance tissue regeneration, we have applied a new tissue engineering approach to this mesh-type prosthesis.

METHODS

The prosthesis consists of a polypropylene mesh tube reinforced with a polypropylene spiral and atelocollagen layer. The cervical tracheas of 18 beagle dogs were replaced with the prosthesis. The collagen layer was soaked with peripheral blood in 6 of the dogs, with bone marrow aspirate in another 6, and with autologous multipotential bone marrow-derived cells (mesenchymal stem cells) in another 6. The dogs were humanely killed at 1 to 12 months after the operation.

RESULTS

All 18 dogs survived the postoperative period. Bronchoscopically, 3 of 4 dogs in the peripheral blood group showed stenosis, whereas no stenosis was evident in all 8 of the dogs in the bone marrow and mesenchymal stem cell groups 6 months after the operation. Faster epithelialization and fewer complications, such as mesh exposure and luminal stenosis, were observed in these two groups than in the peripheral blood group. Histologically, the cells from autologous bone marrow were found to proliferate into the tracheal tissue during the first month. Cilial movement in these two groups was faster than that in the peripheral blood group and recovered to 80% to 90% of the normal level.

CONCLUSIONS

Bone marrow aspirate and mesenchymal stem cells enhance the regeneration of the tracheal mucosa on this prosthesis. This in situ tissue engineering approach may facilitate tracheal reconstruction in the clinical setting.

Endoscopic KTP laser photocoagulation therapy for pharyngolaryngeal venous malformations in adults

OBJECTIVES

Venous malformations are benign lesions with thin, fragile mucosa overlying a vascular stroma. Vascular anomalies often manifest as subglottic lesions in infants, but venous malformations in adults are rare in the pharyngolaryngeal region. The treatments include open and endoscopic surgery; intraoperative bleeding is often troublesome. Angiolytic lasers such as the potassium titanyl phosphate (KTP) laser enable photocoagulation for such hemorrhagic lesions without bleeding; we report findings from a series of adult patients.

METHODS

Seven adults were treated with a KTP laser set at a low power of 1.5 W in continuous mode. Photocoagulation was easily performed for shallow lesions; however, laser irradiation of bulky venous malformations resulted only in surface photocoagulation. In such cases, the crust remaining after photocoagulation was removed, and laser energy was repeatedly delivered until no remnant lesion was seen. An office procedure using flexible endoscopy was performed under topical anesthesia for 1 patient with a limited lesion.

RESULTS

The lesions were well controlled in all cases without major complications. A patient with a large obstructing lesion had a relapse. Because the recurrent lesion is small and the patient does not desire additional treatment at this time, she is being observed carefully.

CONCLUSIONS

Photocoagulation using the KTP laser is a feasible and relatively safe treatment for pharyngolaryngeal venous malformations in adults.

Bone Regeneration of Canine Skull Using Bone Marrow-Derived Stromal Cells and β-Tricalcium Phosphate

OBJECTIVE

The aim of this study was to regenerate high-quality cranial bone using tissue engineering techniques, with subsequent extension to clinical application. Our previous study with a 3-month observation period indicated that a composite scaffold composed primarily of beta-tricalcium phosphate (TCP) had the potential for cranial bone regeneration. In this study, we investigated whether bone marrow derived stromal cells (BSCs) could promote the regeneration of cranial bone as determined after 3 and 6 months.

STUDY DESIGN

The pilot study was conducted with 14 adult beagle dogs.

MATERIALS AND METHODS

Craniotomy was performed in the same manner used clinically. The bone defect (2 x 2 cm) was created at each canine temporoparietal region. The test animals were divided into three groups. In group I, the bone defect was closed by replacing the original free bone flap without filling the residual gaps. In group II, the gap was filled with a composite scaffold consisting of collagen coated beta-TCP and autologous bone fragments with fibrin glue. In group III, autologous cultured BSCs and the composite scaffold were used to fill the gap. The sites of craniotomy were analyzed with three-dimensional computed tomography and histologic examination 3 and 6 months after the operation.

RESULTS

Bone regeneration was observed in groups II and III, with more extensive formation in group III than in group II. In group I, bone regeneration was not observed.

CONCLUSION

This study showed that BSCs have the potential to promote cranial bone regeneration and confirmed the efficacy of a composite scaffold made of beta-TCP and autologous bone fragments with fibrin glue.

Expression of extracellular matrix proteins in the vocal folds and bone marrow derived stromal cells of rats

Vocal fold scarring remains a therapeutic challenge. Our research group has indicated that bone marrow-derived stromal cells (BSCs) may have therapeutic potential in restoration of injured vocal folds. However, it is still unclear how BSCs restore the viscoelasticity of vocal fold mucosa. Since a feature of vocal fold scarring is the disorganization of the extracellular matrix (ECM), it is important to understand how BSCs produce ECM. The present study aimed to clarify ECM gene expression in BSCs, and also examined the effects of hepatocyte growth factor (HGF) on this expression. BSCs obtained from the femurs of four Sprague-Dawley rats were cultured with or without HGF. The mRNA expression of ECM components (type I procollagen, decorin, Has2, CD44, MMP-1, and GAPDH) were examined in cultured BSCs and the vocal fold mucosa by the reverse transcription-polymerase chain reaction (RT-PCR). The mRNA expression of Has2 and MMP-1 was significantly stronger in BSCs than in the vocal folds (P < 0.05). Expression of Has2 in BSCs was significantly increased by the administration of HGF (P < 0.05). There was no significant difference in the gene expression of other ECM molecules between BSCs and vocal fold mucosa. Increased expression of Has2 and MMP-1 genes from BSCs may have a positive potential in the treatment of vocal fold scarring.

In situ tissue engineering of the cricoid and trachea in a canine model

OBJECTIVES

The purpose of the current study was to demonstrate the efficacy of in situ tissue engineering of the cricoid and trachea in a canine model.

METHODS

Marlex mesh tube reinforced with polypropylene threads and covered by collagen sponge was used as a tissue scaffold for airway regeneration in 9 beagle dogs. The anterior half of the cricoid cartilage was resected in 5 dogs, whereas the cricoid cartilage and cervical trachea were simultaneously resected in 4 dogs. The tissue scaffold was implanted into the resultant defect.

RESULTS

Endoscopic examination showed no airway obstruction for a postoperative period of 3 to 40 months in all dogs. Granulation tissue was observed in 2 dogs, and slight mesh exposure in 1 dog, although all were asymptomatic. Light microscopy and electron microscopy showed the endolaryngeal and endotracheal lumen to be covered by ciliated epithelium. According to strain-force measurement, the framework was firmly supported by regenerated tissue, as well as the normal cricoid and trachea.

CONCLUSIONS

Our current tissue scaffold provides a rigid framework for the airway, and the collagen coating invites tissue regrowth around the tube. This study presents the possibility of successful reconstruction of the cricoid and trachea with epithelial regeneration by means of in situ tissue engineering.

Clinical Application of in Situ Tissue Engineering Using a Scaffolding Technique for Reconstruction of the Larynx and Trachea

Objectives:

The objective of the present study was to demonstrate the efficacy of the clinical application of in situ tissue engineering using a scaffolding technique for laryngeal and tracheal tissue.

Methods:

We have developed a tissue scaffold made from a Marlex mesh tube covered by collagen sponge. Based on successful animal experimental studies, in situ tissue engineering with a scaffold implant was applied to repair the larynx and trachea in 4 patients.

Results:

In 1 patient with subglottic stenosis, the thyroid cartilage, cricoid cartilage, and cervical trachea with scarring and granulation were resected and reconstructed by use of the scaffold. In 3 patients with thyroid cancer, the trachea and cricoid cartilage with tumor invasion were resected and the scaffold was implanted into the defect. Postoperative endoscopy during the observation period of 8 to 34 months showed a well-epithelialized airway lumen without any obstruction.

Conclusions:

Our current technique of in situ tissue engineering using a scaffold shows great potential for use in the regeneration of airway defects.

Regeneration of peripheral motor nerve gaps with a polyglycolic acid-collagen tube: technical case report

OBJECTIVE

After previous success in regenerating canine peripheral nerves over 80 mm gaps using a bioabsorbable nerve guide tube, we have extended this method to the treatment of patients experiencing various types of nerve injury. This report describes the treatment of two cases of motor nerve disorder.

METHODS

The bioabsorbable nerve tube was a cylindrically woven polyglycolic acid (PGA) tube filled with collagen. A peripheral motor nerve defect (the frontalis branch of the facial nerve) was reconstructed using this PGA-collagen tube in two patients who experienced posttraumatic unilateral eyebrow ptosis for 3 months.

RESULTS

Five months after surgery, both patients regained their ability to voluntarily lift their eyebrows symmetrically. Electrophysiological examination at 5 months revealed recovery of compound muscle action potential and disappearance of distal latency on the affected side.

CONCLUSION

This is the first clinical report of motor nerve recovery achieved using the PGA-collagen nerve guide tube. The results suggest that use of a PGA-collagen tube is a promising option for the repair of motor nerve defects.

Side population cells in the human vocal fold

OBJECTIVES

The regenerative processes of the vocal fold, or the existence of stem cells in the folds, are unknown. Side population (SP) cells are defined as cells that have the ability to exclude the DNA binding dye, Hoechst 33342. They are regarded as a cell population enriched with stem cells and can be isolated from non-SP cells by a fluorescence-activated cell sorter. This study was designed to determine whether SP cells exist in the human vocal fold, as a first step in elucidating the regenerative mechanisms of the vocal fold.

METHODS

Seven human excised larynges were used in this study. Two were used for fluorescence-activated cell sorter analysis, and 5 were subjected to immunohistochemical analysis with antibodies against an adenosine triphosphate binding cassette transporter family member, ABCG2, which is expressed in SP cells.

RESULTS

The number of SP cells in the human vocal fold was about 0.2% of the total number of cells. ABCG2-positive cells were identified in both the epithelium and subepithelial tissue throughout the entire vocal fold.

CONCLUSIONS

This preliminary study demonstrated the existence of SP cells in the human vocal fold. Further studies are warranted to clarify how these cells work in the vocal fold, particularly in the regenerative process.

Phonomicrosurgery for posterior glottic lesions using triangular laryngoscope

It is important to fully expose the posterior glottis to achieve adequate phonomicrosurgical resection of lesions in the posterior glottis. However, it is often difficult to obtain a sufficient view of the posterior glottis by ordinary direct laryngoscopy. We attempted to expose posterior glottic lesions using a triangular laryngoscope for adequate achievement of the surgery. We have performed phonomicrosurgery for 14 lesions in the posterior glottis including 5 early cancers, 1 dysplasia, 1 hemangioma, and 7 granulomatous lesions. Under general anesthesia, a triangular laryngoscope was set lateral to an intubation tube, shifting the tube anterolaterally toward the opposite side to expose the posterior glottis, which allowed simultaneous visualization of the vocal fold, the lateral wall, and a part of the posterior wall of the posterior glottis. The procedures were completed successfully in all cases. Modified placement of the triangular laryngoscope provided an excellent surgical view including the membranous portion of the vocal fold through the posterior glottis. All lesions have been well controlled during the follow up periods of 6-23 months. The triangular laryngoscope enables an alternative method for posterior glottic exposure. Modified placement of the laryngoscope can be easily performed and provides sufficient exposure of posterior glottic lesions for an adequate resection of those lesions.

Tracheal regeneration after partial resection: a tissue engineering approach

OBJECTIVES

The aims of this study are to investigate the efficiency of a tissue engineering approach to partial tracheal reconstruction and to improve epithelialization of the reconstructed trachea. The trachea must be resected in some cases of cancer or trauma. Various restructuring techniques are used, with no consensus on the best approach. Two problems that arise when treating tracheal defects by conventional techniques are an inability to regenerate ciliated epithelium at the reconstructed site and having to perform multiple procedures to achieve the desired repair. This study is designed to address these problems.

STUDY DESIGN

Preliminary, an animal experiment.

METHODS

Surgery was performed on five adult beagles under anesthesia. After the making of a longitudinal cervical skin incision, the trachea was exposed and a circular defect created. A polypropylene and collagen scaffold preclotted with peripheral blood was inserted to the defect site. Postoperatively, the site was evaluated fiberscopically, histologically, and radiographically.

RESULTS

All dogs did well postoperatively. Fiberscopic examination showed that the implanted scaffolds were completely covered with regenerated mucosa with capillaries in all cases. Histologic data showed ciliated epithelium regenerated at the operated site from 1 month postoperatively. Newly formed cartilage was detected in the specimens from 8 to 12 postoperative months. Computed tomography images revealed the fine luminal contour of the regenerated site.

CONCLUSIONS

Good epithelial regeneration was observed after repair of a round tracheal resection using a simple tissue engineering technique, making the technique a good substitute for conventional approaches to tracheal reconstruction in patients with cancer or trauma.

A case of floppy epiglottis in adult: a simple surgical remedy

A new operative technique for the treatment of floppy epiglottis is introduced in this report. Though its diagnosis is not so difficult by close observations using a flexible fiberscope, it is likely to be treated as an asthma attack or a paradoxical vocal cord movement. In previous reports of upper airway obstruction caused by adult floppy epiglottis: epiglottis prolapse during inspiration, the cause of this condition has been divided broadly into two categories: idiopathic cases and secondary cases. Partial or total epiglottectomy has been usually reported for the treatment of the relief of airway obstruction caused by a floppy epiglottis. It is very difficult to decide adequately how much volume of epiglottis to cut without postoperative sequelae. A V-shaped partial epiglottidectomy is described for its treatment. This technique is very easy, simple, and effective.

5-Fluorouracil Ointment for the Treatment of Otitis Media With Effusion

OBJECTIVES/HYPOTHESIS

Our aim was to evaluate the combined effect of 5-fluorouracil (5-FU) and myringotomy for the treatment of otitis media with effusion (OME). OME is usually treated with medication, myringotomy, or insertion of a ventilation tube (VT). Except for VT insertion, however, treatment effects are short-lived. VT insertion has numerous sequelae: increased susceptibility to infection, large perforation of the tympanic membrane, cholesteatoma, and eventual hearing deterioration. We estimated the depressant action of 5-FU on normal cell proliferation in vitro. In addition, clinically, we assessed whether 5-FU has the potential to prolong the effect of myringotomy.

STUDY DESIGN

An in vitro study and a clinical study were conducted.

MATERIALS AND METHODS

In study I, fibroblasts harvested from the peritoneum of three green fluorescent protein transgenic mice were cultured with different doses of 5-FU. After 2 weeks, their proliferation rates were compared. In study II, patients (54 males, 47 females) were selected randomly from a group of patients with intractable OME. Myringotomy with or without a single dose of 5-FU ointment (approximately 0.10-0.30 mg) was performed in group I (n = 64) and group II (n = 37), respectively. The natural closure rates of the tympanic membrane were assessed in both groups.

RESULTS

In vitro, 5-FU inhibited the growth of fibroblasts in a dose-dependent manner. The average time to tympanic membrane closure was 20.5 days in group I and 8.1 days in group II. No adverse events were observed in either group.

CONCLUSIONS

Topical application of 5-FU ointment is useful in prolonging the effect of myringotomy. 5-FU ointment therapy is easy, safe, and cost-effective and may be of wide application.

Effect of Fibroblasts on Tracheal Epithelial Regenerationin vitro

Several artificial grafts for covering deficient trachea have been produced through tissue engineering. Recently, our group clinically used an artificial trachea made from collagen sponge for patients with noncircumferential tracheal resection. However, the slowness of epithelial regeneration on the surface of the artificial trachea was confirmed as one particular problem. In this study, we co-cultured tracheal epithelial cells with fibroblasts and examined effects of fibroblasts on epithelial regeneration in vitro. Fibroblasts activated epithelial cell proliferation and migration. In co-culture with fibroblasts, epithelial cells reconstructed pseudostratified epithelium, which was composed of ciliated, goblet, and basal cells. Furthermore, a basement membrane was reconstructed between epithelial cells and fibroblasts, and integrin beta4 was also observed there. Fibroblasts rapidly increased mucin secretion by epithelial cells. These results indicate that stimulatory effects of fibroblasts on epithelial cell migration, proliferation, and differentiation would reduce the time required for covering of epithelial cells on the defect of luminal surface and hasten regeneration of morphologically and functionally normalized epithelium involving the reconstruction of basement membrane.