Hiroo Umeda

Regenerative Treatment for Tympanic Membrane Perforation

Objective: To establish a tissue engineering therapy for the treatment of large tympanic membrane perforation (TMP) without the need for conventional surgical therapy. Study Design: Randomized control trial. Setting: General hospital. Patients and Methods: A total of 63 chronic TMPs were randomly selected from outpatients. Intervention: Of the total 63 chronic TMPs, 53 were randomly assigned to the basic fibroblast growth factor (b-FGF) group and the remaining 10 were randomly assigned to the control group. Materials used for the TM repair were gelatin sponge and fibrin glue with/without b-FGF. After creating a mechanical disruption of the edge of the TMP, a gelatin sponge was immersed in b-FGF or saline (for the control group) and placed over the perforation. Fibrin glue was dripped over the sponge as a sealant. Main Outcome Measures: The effectiveness of this therapy was evaluated by closure rates, hearing level, and sequelae 3 weeks after treatment. The treatment was repeated up to 4 times for cases in which complete closure of the TMP was not achieved after 1 round of treatment. Results: Complete closure of the TMP was achieved in more than 98.1% (52/53) of the patients in the b-FGF group and 10% (1/10) of the patients in the control group. The average hearing level of all patients with successful TM repair was improved. Serious sequelae were not observed in any patient. Conclusion: This study demonstrates that a combination of gelatin sponge, b-FGF, and fibrin glue enables the regeneration of the TM without conventional operative procedures. This innovative regenerative therapy is an easy, safe, cost-effective, and minimally invasive outpatient treatment.

Chronic vocal fold scar restoration with hepatocyte growth factor hydrogel

Therapeutic challenges exist in the management of vocal fold scarring. We have previously demonstrated the therapeutic potential of hepatocyte growth factor (HGF) in the management of acute phase vocal fold scarring using a novel hydrogel‐based HGF drug delivery system (DDS). However, the effect of HGF on matured vocal fold scarring remains unclear. The current study aims to investigate the effect of HGF‐DDS on chronic vocal fold scarring using a canine model.

Drug delivery system of hepatocyte growth factor for the treatment of vocal fold scarring in a canine model.

Objectives: Vocal fold scarring remains a therapeutic challenge. Previous studies have indicated that hepatocyte growth factor (HGF), a strong antifibrotic element, has therapeutic potential for restoring scarred vocal folds. To enhance the effect of HGF in vivo, we developed a novel drug delivery system (DDS) in which HGF is embedded in gelatin hydrogel and continuously released over a period of 2 weeks. In the present study we investigated the therapeutic efficacy of the HGF DDS on vocal fold scarring by using a canine model. Methods: The vocal folds of 8 beagles were unilaterally scarred by stripping the entire layer of the lamina propria. The contralateral vocal folds were kept intact as normal controls. One month after the procedure, hydrogels (0.5 mL) containing 1 μg of HGF were injected into the scarred vocal folds of 4 dogs (HGF-treated group), whereas hydrogels containing saline solution were injected in the other 4 dogs (sham group). Histologic and vibratory examinations were completed for each group 6 months after the initial surgery. Results: The excised larynx experiments showed significantly better vibration in terms of mucosal wave amplitude and glottal closure in the HGF-treated group compared to the sham group. Histologic evaluation of the vocal folds indicated remarkable reduction in collagen deposition and tissue contraction, with favorable restoration of hyaluronic acid and elastin in the HGF-treated group. Conclusions: The present findings suggest that the novel HGF DDS may provide favorable effects in restoring the vibratory properties of scarred vocal folds.

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 fsp1 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.

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 β‐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.

A tissue-engineering approach for stenosis of the trachea and/or cricoid.

Abstract 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.

Experimental regeneration of canine larynx: a trial with tissue engineering techniques

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.

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

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.

Laryngeal regeneration using tissue engineering techniques in a canine model.

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 × 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.

In situ tissue engineering of canine skull with guided bone regeneration

Conclusion: Calcium alginate (CA) membrane prevents excessive fibrous tissue intrusion and/or dislocation of a bone scaffold. However, CA membrane did not always accelerate cranial bone regeneration. Objective: We previously reported skull regeneration using a bone substitute material (BSM), which consisted of collagen-coated beta-tricalcium phosphate and autologous bone fragments, and bone marrow-derived stromal cells (BSCs). However, excessive fibrous tissue intrusion or dislocation of the BSM occasionally interrupted bone regeneration. To avoid such problems, we examined CA membrane, which is useful for guided bone regeneration (GBR), to investigate whether this material maintains the bone regenerative space. Materials and methods: Bone defects (2×2 cm) were created in the skulls of 12 adult beagle dogs using the same clinical procedure. Four experimental models were tested with or without BSM plus BSCs or CA membrane. In group I, the original free bone flap was replaced at the defect. In group II, after replacing the bone flap, the defect was covered with CA membrane. In group III, BSM plus BSCs were used as a gap filler. In group IV, BSM plus BSCs and CA membrane were applied. Histological examinations were performed 3 and 6 months after the operation. Results: In groups I and II, bone regeneration was not observed but fibrous tissue intrusion was prevented in group II. Bone neogenesis was more observed in group III than in group IV at 3 months (p<0.05). At 6 months, the regenerated areas were larger than those observed at 3 months, but the differences between groups III and IV were not statistically significant.