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Conclusion: Tight fixation of the artificial trachea is important for epithelialization and tracheal stenosis. Objective: The authors have developed an artificial trachea and have used it for tracheal reconstruction. Although various studies on tracheal reconstruction have been conducted, no studies have examined the effect of artificial tracheal fixation on tracheal stenosis and regeneration. Therefore, the purpose of the present study was to evaluate the effect of artificial tracheal fixation. Study design: Preliminary animal experiment. Methods: Artificial tracheae were implanted into rabbits with partial tracheal defects. Tracheal stenosis and regeneration of the tracheal epithelium on the artificial tracheae were evaluated by endoscopic examination, scanning electron microscopic analysis, and histological examination. The artificial tracheae fixed to the tracheal defects were classified into three groups (0-point, 4-point, and 8-point) by the number of fixation points. Results: At 14 and 28 days post-implantation, the luminal surface of the implantation area was mostly covered with epithelium in all fixation groups. However, a small amount of granulation tissue was observed in the 0-point fixation group at 14 days post-implantation. Moreover, tracheal stenosis did not occur in the 8-point fixation group, but stenosis was detected in the other groups. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Objectives/Hypothesis: Due to its anatomical features, the chorda tympani nerve (CTN) is sometimes sacrificed during middle ear surgery, resulting in taste dysfunction. We examined the effect of placing an artificial nerve conduit, a polyglycolic acid (PGA)-collagen tube, across the gap in the section of the resected chorda tympani nerve (CTN) running through the tympanic cavity. Methods: The CTN was reconstructed with a PGA-collagen tube in three patients with taste disturbance who underwent CTN resection. To evaluate the effect of the reconstruction procedure on the patients' gustatory function, we measured the patients' electrogustometry (EGM) thresholds. The patients were followed-up for at least two years. Results: Gustatory function was completely restored in all of the patients after the reconstruction. The patients' EGM thresholds exhibited early improvements within one to two weeks and had returned to their normal ranges within three months. They subsequently remained stable throughout the two-year follow-up period. In a patient who underwent a second surgical procedure, it was found that the PGA-collagen tube used in the first surgical procedure had been absorbed and replaced by new CTN fibers with blood vessels on their surfaces. Conclusion: These results suggest that reconstruction of the CTN with an artificial nerve conduit, a PGA-collagen tube, allows functional and morphological regeneration of the nerve and facilitates the recovery of taste function. PGA-collagen tubes might be useful for repairing CTNs that are resected during middle ear surgery. Further research is required to confirm these preliminary results although this is the first report to describe the successful regeneration of a nerve running through an aerial space. [ABSTRACT FROM AUTHOR]

Objectives: Our group has had good results in trachea! mucosal regeneration using a collageti 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: Muco.sal 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 trachea! 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 trachea! tissue. [ABSTRACT FROM AUTHOR]

Conclusion: Our technique for tracheal regeneration using a collagen vitrigel scaffold affords a feasible approach for accelerating epithelial regeneration on the intraluminal surface of the host tracheal defect. Objectives: The purpose of the study was to quantitatively evaluate the effectiveness of a collagen vitrigel scaffold for the regeneration of the tracheal epithelium. Methods: The collagen vitrigel scaffold was developed by conjugating a collagen vitrigel membrane to a collagen sponge to promote both epithelial cell growth and mesenchymal cell infiltration. The collagen vitrigel scaffold was implanted into tracheal defects in rats as the vitrigel model, and a conventional collagen sponge was implanted as a control model. The structure of the regenerated tissue was observed and thickness of the epithelium was quantitatively evaluated by histological examination. Results: Histological findings showed the surface of the collagen vitrigel scaffold to be flat in comparison with that of the conventional collagen sponge. At 7, 14, and 28 days post-implantation, the average thickness of the regenerated epithelial layer in the vitrigel model group was greater than that in the control group. [ABSTRACT FROM AUTHOR]

Objectives: Vocal fold scarring remains a therapeutic challenge. A new regenerative approach is needed to restore disorganized extracellular matrix. Tissue regeneration requires appropriate cells and a scaffold. Bone marrow-derived mes- enchymal stromal cells (BMSCs) are multipotent and secrete many kinds of growth factors to regenerate tissues. Ate- locollagen sponges have many large pores that permit cell entry. The present study was performed to evaluate whether implantation of an atelocollagen sponge plus BMSCs is effective for the treatment of vocal fold scarring. Methods: Twelve beagles underwent implantation of an atelocollagen sponge or of an atelocollagen sponge with autolo- gous BMSCs ( 1.0 x 106 cells) in the subepithelial pockets of scarred vocal folds. Six months after the operation, vibratory examinations and histologie examinations were performed. Results: Mucosal vibrations improved significantly for the atelocollagen sponge-implanted vocal folds. Histologie analyses revealed favorable restoration of the extracellular matrix in the lamina propria. Increased distribution of hyaluronic acid and decreased dense collagen deposition were also noted. These improvements were enhanced by implantation of BMSCs. Conclusions: Implantation of atelocollagen sponges with autologous BMSCs into scarred vocal folds significantly increased hyaluronic acid distribution and decreased dense collagen deposition in the lamina propria, leading to better mucosal vibration. [ABSTRACT FROM AUTHOR]

Objectives: We previously reported that polypropylene mesh covered with collagen sponge is a useful material for the regeneration of the trachea and the cricoid cartilage. The aim of this study was to regenerate larynges after partial hemilaryngectomy with this new biomaterial. Methods: A left partial hemilaryngectomy was performed on 12 adult beagles. The defect size was about 1.8 x 1.0 cm. Both sides of polypropylene mesh were coated with either 1% or 3% collagen sponge. This scaffold was wrapped in fascia lata harvested from the left thigh and then fixed in place over the defect. Endoscopic examinations were performed periodically. Six months after treatment, 3-dimensional computed tomographic scanning was performed. Vibratory examinations were also performed with excised larynges. Results: In the 1 % collagen group, exposure or dislocation of the mesh was found in 3 of 6 cases, but in the 3% group, no exposure of the mesh was seen. The morphological findings in the vocal fold were better in the 3% group than in the 1% group, but a difference in the vertical levels of the vocal folds was found in both groups. Conclusions: This study suggests that 3% collagen-coated polypropylene mesh wrapped with autologous fascia is a useful material for laryngeal regeneration. [ABSTRACT FROM AUTHOR]

Conclusion: This new regenerative therapy shows great potential for the treatment of stenosis of the trachea and/or cricoids (STC). Objectives: To estimate the potential of tissue-engineered artificial trachea (AT) for treatment of STC in clinical applications. We previously reported that AT was a useful material for implantation into a tracheal defect after resection of cancer. There are many causes of stenosis of the respiratory tract and STC is particularly difficult to treat. Methods: The AT was a spiral stent composed of Marlex mesh made of polypropylene and covered with collagen sponge made from porcine skin. Three patients with STC were treated by this tissue-engineering method. All of them suffered from STC caused by long endotracheal intubations. They underwent a two-stage operation. In the first operation, after resection of the stenotic regions, the edge of the tracheal cartilage was sutured to the edge of the skin. The tracheal lumen was exposed and a T-shaped cannula was inserted into the large tracheostoma. At 3 weeks to 2 months after the first operation, the trachea and skin were separated. The trimmed AT with venous blood and basic fibroblast growth factor (b-FGF) was then implanted into the cartilage defect. Results: Postoperatively, all patients were able to breathe easily and had no discomfort in their daily activities. Six months after the second operation, we observed enough air space in the trachea and cricoid by computed tomography (CT) imaging and fiber endoscopy. [ABSTRACT FROM AUTHOR]

Objectives: Our previous studies focused on basic research and the clinical applications of an artificial trachea. However, the prefabricated artificial trachea cannot be utilized for pediatric airways, because the tracheal frame needs to expand as the child develops. The purpose of this study was to evaluate the potential of induced pluripotent stem (iPS) cells for the regeneration of the tracheal wall. Methods: We cultured iPS cells in a 3-dimensional (3-D) scaffold in chondrocyte differentiation medium (bioengineered scaffold model), and the results were compared with those in a 3-D scaffold without iPS cells (control scaffold model). The 3-D scaffolds were implanted into tracheal defects in 8 nude rats. After 4 weeks, the regenerated tissue was histologically examined. Results: Implanted iPS cells were confirmed to exist in all 5 rats implanted with bioengineered scaffolds. Cartilage-like tissue was observed in the regenerated tracheal wall in 2 of the 5 rats in the bioengineered scaffold model, but in none of the 3 rats in the control scaffold model. Conclusions: Implanted iPS cells were confirmed to exist in the bioengineered scaffold. Cartilage-like tissue was regenerated in the trachea! defect. This study demonstrated the potential of iPS cells in the regeneration of the trachea! wall. [ABSTRACT FROM AUTHOR]

Objectives: Although our group has had mostly successful results with clinical application of a tracheal prosthesis, delayed epithelial regeneration remains a problem. In our previous studies using rats, it was demonstrated that tracheal fibroblasts accelerated proliferation and differentiation of the tracheal epithelium in vitro and in vivo. The purpose of this study was to evaluate the effects of fibroblasts on epithelial regeneration in larger tracheal defects in rabbits. Methods: We developed a bioengineered scaffold, the luminal surface of which was coated with fibroblasts. This scaffold was implanted into tracheal defects in 12 rabbits (bioengineered group), and scaffolds without fibroblasts were implanted in 12 rabbits (control group). The regenerated epithelium was histologically examined by light microscopy, scanning electron microscopy, and immunohistochemical studies. Results: In the bioengineered group, a stratified squamous epithelium was observed on the surface 7 days after transplantation. However, in the control group, the scaffolds were exposed. Fourteen days after implantation, a columnar ciliated epithelium was observed in the bioengineered group. The average thickness of the regenerated epithelium in the bioengineered group was significantly greater than that in the control group. Conclusions: This study indicated that fibroblasts had a stimulatory effect that hastened regeneration of the epithelium in large tracheal defects. [ABSTRACT FROM AUTHOR]

Conclusion: Since this tissue engineering technique is cost-effective and is less invasive to patients, it may replace conventional approaches in laryngeal reconstructive surgeries. Objective: Laryngeal cancer is one of the most prevalent cancers in the head and neck region, and frequently requires surgical resection. Although there are many ways to reconstruct the larynx after resection, donor tissue is usually required. Recently, tissue engineering techniques have become widely accepted in clinical medicine and have already been applied to some organs. This animal experiment was designed to elucidate the efficacy of laryngeal regeneration using tissue engineering technique. Materials and methods: A bioartificial scaffold was designed from a replica of a canine larynx. A dental cast was used to replicate the intricate inside shape of the larynx. After copying its shape on a polypropylene mesh sheet, this sheet was coated with spongy collagen from porcine skin. A hemilaryngectomy was performed on beagle dogs under general anesthesia. Then the scaffold, preclotted with a mixture of peripheral blood and bone marrow-derived stromal cells, was implanted and fixed. The postoperative status was examined fiberscopically. Results: On the eighth day after the operation, the surface of the implant was covered with soft tissue. Finally, the implant was completely covered with regenerated mucosa. [ABSTRACT FROM AUTHOR]

The objective of this study was to establish a method for regenerating mastoid air cells and their functions for clinical use in incurable otitis media. For this clinical study three patients (one male, two female) were randomly selected from patients with severe cholesteatoma about to undergo staged operations. Hydroxy-apatite in three-dimensional, honeycomb-like structures (3D-HA) were used as artificial pneumatic bones. This 3D-HA is made of calcium phosphate and has a high percentage of micropores (90%). Its surface is coated with collagen. At the first stage of tympanoplasty, collagen-coated 3D-HA was put into the opened mastoid cavity and fixed by fibrin glue. Recovery of mastoid aeration and regeneration of the pneumatic air cells of the mastoid cavity were estimated on CT scan images after the first operation. Aeration was recovered in all cases. The mastoid air cells were regenerated in two cases. In the failed case, subcutaneous connective tissues and granulations invaded into the spaces of the 3D-HA. This study demonstrated that mucosa would grow on the surface of a 3D-HA implant and could provide gas exchange functions in the newly opened mastoid cavity. This tissue engineering method may be a possible treatment for intractable otitis media. [ABSTRACT FROM AUTHOR]

Mastoid is a pneumatic bone, composed of small interconnecting chambers covered by a mono-layer of mucosa with an abundant blood supply. One of its main functions is gas exchange according to the concentration/pressure gradient. The final goal of our research project is to regenerate mastoid air cells and their unique physiologic functions. The aim of the present study is to determine appropriate cultivating conditions for the cells cultured on the surface of artificial hydroxyapatite. In our in vitro experiment, to imitate the skeleton of mastoid bone, we used two types of three-dimensional hydroxyapatite (3D-HA), i.e. with a high (90%) and low (60%) percentage of micropores. The former type was divided into two groups: collagen-coated and non-coated. Canine mucosal- and bone marrow-derived stromal cells (BSCs), from the oral floor and femur respectively, were harvested and cultured on the 3D-HA under different conditions. To estimate the proliferation/distribution of the cultured cells over the surface of the 3D-HA, these cells were stained with the dye DiI and hematoxylin-eosin. There were no significant differences in the proliferation of cultured cells on the 3D-HA with high and low percentages of micropores. Collagen-coated HA was a better material for the cultured cells compared with the non-coated HA. Co-cultured mucosal and BSCs proliferated better than those cultured separately. In conclusion, this tissue engineering technique may be applied for the regeneration of mastoid air cells. [ABSTRACT FROM AUTHOR]

The recurrent laryngeal nerve (RLN) does not regenerate well after it has been cut, and no current surgical methods achieve functional regeneration. Here, we evaluate the functional regeneration of the RLN after reconstruction using a biodegradable nerve conduit or an autologous nerve graft. The nerve conduit was made of a polyglycolic acid (PGA) tube coated with collagen. A 10-mm gap in the resected nerve was bridged by a PGA tube in 6 adult beagle dogs (group 1) and by an autologous nerve graft in 3 dogs (group 2). Fiberscopic observation revealed functional regeneration of the RLN in 4 of the 6 dogs in group 1. No regeneration of the RLN was observed in any dog in group 2. We also tested for axonal transport, and measured the compound muscle action potential. The RLN can be functionally regenerated with a PGA tube, which may act as a scaffold for the growth of regenerating axons. [ABSTRACT FROM AUTHOR]

We evaluated facial nerve regeneration using a collagen tube as a nerve conduit in five cats. In three 5 mm of the facial nerve were resected, a collagen tube was implanted, and a 5 mm segment of the opposite facial nerve was resected, reversed 180°, and sutured back as an autologous nerve graft. In one a collagen tube was implanted on one side, and in the remaining one a 5 mm nerve segment was reversed. Histological, electrophysiological, and horseradish peroxidase labelling examinations were carried out 4–24 weeks postoperatively. Histological study showed that the nerve was well vascularised and regenerated. Electrophysiological examination confirmed the recovery of evoked electromyograms through to the regenerated axons. Horseradish peroxidase examination also confirmed restoration of the whole facial nerve. The collagen tube is an efficient nerve conduit. [ABSTRACT FROM AUTHOR]

Objective: There continue to be therapeutic challenges in the management of vocal fold scarring. We previously showed that basic fibroblast growth factor (bFGF) injection has therapeutic potential for vocal fold scarring. However, the working time of bFGF is relatively short, and multiple injections were required in many cases to obtain the regenerative effect. An efficacious delivery system for bFGF has yet to be established. We designed a method of sustained drug delivery system (DDS) of bFGF by using a gelatin hydrogel. Hydrogel has been developed for targeted delivery and controlled release of bFGF. Hydrogel of the particle type is also injectable and commercially available. The current study aims to investigate the effects of a single injection of bFGF-DDS on acute vocal fold scarring using a canine model.Methods: Vocal folds from eight beagles were unilaterally scarred by stripping the lamina propria. One month later, hydrogels (0.5ml) containing 10μg of bFGF were injected into the scarred vocal folds of four beagles (FGF-hydrogel group). Saline (0.5ml) was injected into the other four beagles (sham group). Vibratory and histological examination of excised larynges was performed 5 months after treatment. Comparative analysis between the current data and our previous data with repeated injection of bFGF solution was also completed.Results: Vibratory examination demonstrated significantly improved vibration in the bFGF hydrogel-treated group. Histological examination of the bFGF hydrogel group showed restoration of hyaluronic acid in the lamina propria as compared to sham. Comparison between the DDS system and our previous bFGF solution injection indicated better effects of the DDS system on vibratory amplitude.Conclusion: A single injection of bFGF hydrogel has regenerative effects on acute vocal fold scarring, which is at least similar to repeated injection of bFGF solution. [ABSTRACT FROM AUTHOR]

Abstract: Background: The aim of this study was to examine whether transplantation of adipose-derived stem cells (ADSCs) improves healing of a gastrotomy closure in rats. In digestive surgery, anastomotic leakage is a serious postoperative complication and anastomotic stenosis may reduce quality of life. Recent studies have suggested that ADSCs play material roles in intestinal healing, acceleration of angiogenesis, and reduction of fibrosis, and treatment with ADSCs may improve healing. Materials and methods: ADSCs were isolated from intra-abdominal white adipose tissue of 40 male Wistar rats (weight 300 g) in four groups (n = 10 each). Gastrotomy closures were prepared surgically in all rats. Controls were treated with phosphate-buffered saline injection and sacrificed 7 d (group 1) or 28 d (group 3) after the surgery. Other animals were treated with locally autotransplanted ADSCs (labeled by CM-DiI) and sacrificed 7 d (group 2) or 28 d (group 4) after the surgery. Histopathologic features were evaluated in the four groups. Results: Injection of ADSCs significantly enhanced angiogenesis and collagen deposition after 7 d, indicating improved healing of the gastrotomy closure. In contrast, ADSC transplantation significantly reduced collagen deposition after 28 d. The bursting pressure was higher in the transplant groups after 7 d. Conclusions: ADSCs enhance tissue regeneration in gastrotomy closures by accelerating angiogenesis and fibrosis in the early healing period. In the late period, ADSCs prevent excessive fibrosis and assist in regeneration of tissues that closely resemble the native structure. These results suggest that therapy with transplanted ADSCs might improve postoperative complications in digestive surgery. [Copyright &y& Elsevier]