Mitsuyoshi Imaizumi

Stiffness of salivary gland and tumor measured by new ultrasonic techniques: Virtual touch quantification and IQ.

OBJECTIVE To evaluate normal salivary gland stiffness and compare the diagnostic performance of virtual touch quantification (VTQ) and virtual touch imaging quantification (VTIQ) for head and neck tumor. METHODS A total of 92 measurements were examined, comprising 77 normal salivary glands, 11 benign tumors and four malignant tumors. Examinations were made to evaluate normal salivary gland stiffness and compare the diagnostic performances of new ultrasonic techniques regarding head and neck tumor. RESULTS The mean values of VTQ and VTIQ for the normal salivary group (NSG) were 1.92 and 2.06m/s, respectively. The VTQ and VTIQ values were correlative, and there were no statistical differences in each mean value between the normal parotid glands and submandibular glands. For the benign tumor group (BTG), four of the 11 values were non-numeric and were considered above the measurable range. The mean VTIQ value for the BTG was 4.24m/s. For the malignant tumor group (MTG), all four VTQ values were non-numeric. The mean VTIQ value for the MTG was 6.52m/s. For the mean VTIQ values, significant differences were observed among the three groups. The optimum VTQ cutoff value to detect malignant tumors was above the measurable range, and that of VTIQ was 4.83m/s. CONCLUSION The VTQ and VTIQ values were correlative for the salivary glands, and the stiffnesses of normal parotid glands were almost same as those of submandibular glands. VTQ and VTIQ values could be applied for the preoperative diagnosis in salivary gland lesions.

Regeneration of tracheal epithelium using a collagen vitrigel-sponge scaffold containing basic fibroblast growth factor.

Objectives: Our group has had good results in tracheal mucosal regeneration using a collagen vitrigel–sponge scaffold in an animal model. In this study, the effectiveness of this scaffold with the application of basic fibroblast growth factor (b-FGF) was investigated. Methods: A collagen vitrigel–sponge scaffold was fabricated with simultaneous addition of b-FGF. Three types of collagen vitrigel–sponge scaffolds were made: No b-FGF, 10 ng of b-FGF, and 100 ng of b-FGF. At 3, 5, 7, and 14 days after implantation in rats, the tracheas were removed and histologically evaluated. The regeneration of mucosal epithelium and the subepithelial layer was evaluated. Results: Mucosal epithelium, including pseudostratified epithelium and ciliated cells, regenerated earlier in the scaffolds when b-FGF was applied than when b-FGF was not applied. Regeneration of the subepithelial layer, infiltration of inflammatory cells and fibroblasts, and angiogenesis were promoted earlier in the scaffolds with b-FGF application. Conclusions: Our technique for tracheal reconstruction using collagen vitrigel–sponge scaffolds with b-FGF application affords a feasible approach for accelerating the regeneration of the intraluminal surface and subepithelial layer of tracheal tissue.

Surgical Treatment of Laryngeal Papillomatosis Using Narrow Band Imaging

Laryngeal papillomatosis has a high rate of recurrence after surgery. Narrow band imaging (NBI) is a novel optical enhancement technology used for the diagnosis. This is the first report to date to indicate the availability of the combination of laryngomicro surgery and videoendoscopic surgery for laryngeal papillomatosis using NBI technology. The patients were a 34-year-old man and a 30-year-old man. Both patients underwent surgery in another hospital. However, due to recurrence, they were subsequently referred to the authors’ department for further evaluation. The presence of papillomas was confirmed by NBI, and the papillomas were removed using an XPS Micro Debrider and a CO2 laser. Using the NBI system, the border between the normal mucosa and the papillomas could be clearly identified, allowing precise resection. Further treatment on the lesions has been carried out several times to date using NBI. The lesions have now been eradicated without further recurrence.

Epithelial Cells Are Active Participants in Vocal Fold Wound Healing: An In Vivo Animal Model of Injury

Vocal fold epithelial cells likely play an important, yet currently poorly defined, role in healing following injury, irritation and inflammation. In the present study, we sought to identify a possible role for growth factors, epidermal growth factor (EGF) and transforming growth factor-beta 1 (TGFβ1), in epithelial regeneration during wound healing as a necessary first step for uncovering potential signaling mechanisms of vocal fold wound repair and remodeling. Using a rat model, we created unilateral vocal fold injuries and examined the timeline for epithelial healing and regeneration during early and late stages of wound healing using immunohistochemistry (IHC). We observed time-dependent secretion of the proliferation marker, ki67, growth factors EGF and TGFβ1, as well as activation of the EGF receptor (EGFR), in regenerating epithelium during the acute phase of injury. Ki67, growth factor, and EGFR expression peaked at day 3 post-injury. Presence of cytoplasmic and intercellular EGF and TGFβ1 staining occurred up to 5 days post-injury, consistent with a role for epithelial cells in synthesizing and secreting these growth factors. To confirm that epithelial cells contributed to the cytokine secretion, we examined epithelial cell growth factor secretion in vitro using polymerase chain reaction (PCR). Cultured pig vocal fold epithelial cells expressed both EGF and TGFβ1. Our in vivo and in vitro findings indicate that epithelial cells are active participants in the wound healing process. The exact mechanisms underlying their roles in autocrine and paracrine signaling guiding wound healing await study in a controlled, in vitro environment.

Regenerative process of tracheal epithelium using a collagen vitrigel sponge scaffold

Our group has developed a collagen vitrigel sponge scaffold containing basic fibroblast growth factor (b‐FGF) for tracheal reconstruction. In this study, we have investigated the regenerative process of tracheal epithelium histologically and morphologically.

In Vitro Epithelial Differentiation of Human Induced Pluripotent Stem Cells for Vocal Fold Tissue Engineering

Objectives: We determined the feasibility and optimization of differentiating human induced pluripotent stem cells (hiPS) into nonkeratinized stratified squamous epithelial cells for vocal fold engineering. Methods: hiPS were cultured and assessed for differentiation in 3 conditions: A 3-dimensional (3D) hyaluronic acid (HA) hydrogel scaffold, a 3D HA hydrogel scaffold with epidermal growth factor (EGF), and a 3D HA hydrogel scaffold co-cultured with human vocal fold fibroblasts (hVFF). After 1, 2, and 4 weeks of cultivation, hiPS were selected for histology, immunohistochemistry, and/or transcript expression analysis. Results: At 4 weeks, hiPS cultivated with hVFF or with EGF had significantly decreased levels of Oct 3/4, indicating loss of pluripotency. Immunofluorescence revealed the presence of pancytokeratin and of cytokeratin (CK) 13 and 14 epithelial-associated proteins at 4 weeks after cultivation in hiPS EGF and hiPS hVFF cultures. The transcript expression level of CK14 was significantly increased for hiPS hVFF cultures only and was measured concomitantly with cell morphology that was clearly cohesive and displayed a degree of nuclear polarity suggestive of epithelial differentiation. Conclusions: We found that hiPS cultivated in 3D HA hydrogel with hVFF demonstrated the most robust conversion evidence to date of epithelial differentiation. Further work is necessary to focus on amplification of these progenitors for application in vocal fold regenerative biology.

Classification for animal vocal fold surgery: resection margins impact histological outcomes of vocal fold injury.

Extent of vocal fold injury impacts the nature and timing of wound healing and voice outcomes. However, depth and extent of the lesion created to study wound healing in animal models vary across studies, likely contributing to different outcomes. Our goal was to create a surgery classification system to enable comparison of postoperative outcomes across animal vocal fold wound‐healing studies.

Generation of airway epithelial cells with native characteristics from mouse induced pluripotent stem cells

Airway epithelial cells derived from induced pluripotent stem (iPS) cells are expected to be a useful source for the regeneration of airway epithelium. Our preliminary study of embryoid body (EB) formation and the air-liquid interface (ALI) method suggested that mouse iPS cells can differentiate into airway epithelial cells. However, whether the cells generated from mouse iPS cells had the character and phenotype of native airway epithelial cells remained uninvestigated. In this study, we generated airway epithelial cells from EBs by culturing them under serum-free conditions supplemented with Activin and bFGF and by the ALI method and characterized the iPS cell-derived airway epithelial cells in terms of their gene expression, immunoreactivity, morphology, and function. Analysis by quantitative real-time reverse transcription-polymerase chain reaction(RT-PCR) revealed that the expression of the undifferentiated cell marker Nanog decreased time-dependently after the induction of differentiation, whereas definitive endoderm markers Foxa2 and Cxcr4 were transiently up-regulated. Thereafter, the expression of airway epithelium markers such as Tubb4a, Muc5ac, and Krt5 was detected by RT-PCR and immunostaining. The formation of tight junctions was also confirmed by immunostaining and permeability assay. Analysis by hematoxylin and eosin staining and scanning electron microscopy indicated that the cells generated from mouse iPS cells formed airway-epithelium-like tissue and had cilia, the movement of which was visualized and observed to be synchronized. These results demonstrate that the airway epithelial cells generated by our method have native characteristics and open new perspectives for the regeneration of injured airway epithelium.

Structural and functional vocal fold epithelial integrity following injury

An intact epithelium is an important part of vocal fold defense. Damage to the epithelium can compromise vocal fold homeostasis and protection of the host tissue from viral and bacterial invasion. Elucidating the effects of damage on epithelial architectural and barrier integrity provides insight into the role of epithelium in protecting vocal folds. Using an animal model, we evaluated the time course of structural and functional epithelial restoration following injury.

Effect of Structural Differences in Collagen Sponge Scaffolds on Tracheal Epithelium Regeneration.

Objective: We developed an in situ regeneration-inducible artificial trachea composed of a porcine collagen sponge and polypropylene framework and used it for tracheal reconstruction. In the present study, collagen sponges with different structures were prepared from various concentrations of collagen solutions, and their effect on the regeneration of tracheal epithelium was examined. Methods: Collagen sponges were prepared from type I and III collagen solutions. The structures of the sponges were analyzed using scanning electron microscopy (SEM). Artificial tracheae, which were formed using the collagen sponges with different structures, were implanted into rabbits, and regeneration of the tracheal epithelium on the artificial tracheae was evaluated by SEM analysis and histological examination. Results: The SEM analysis showed that collagen sponges prepared from 0.5% and 1.0% collagen solutions had a porous structure. However, the sponges prepared from a 1.5% collagen solution had a nonporous structure. After implantation of artificial tracheae prepared from 0.5% and 1.0% collagen solutions, their luminal surfaces were mostly covered with epithelium within 14 days. However, epithelial reorganization occurred later on artificial tracheae prepared from the 1.5% collagen solution. Conclusion: Collagen sponges with a porous structure are suitable for regeneration of the tracheal epithelium in our artificial trachea.