Ryo Takagi

Treatment of oesophageal ulcerations using endoscopic transplantation of tissue engineered autologous oral mucosal epithelial cell sheets in a canine model

Background: With the recent development of endoscopic submucosal dissection (ESD), large oesophageal cancers can be removed with a single procedure, with few limits on the resectable range. However, after aggressive ESD, a major complication that arises is postoperative inflammation and stenosis that can considerably affect the patient’s quality of life. Aims: To examine a novel treatment combining ESD and the endoscopic transplantation of tissue-engineered cell sheets created using autologous oral mucosal epithelial cells, in a clinically relevant large animal model. Methods: Oral mucosal epithelial cells, harvested from beagle dogs, were cultured under normal conditions at 37°C, on temperature-responsive dishes. After ESD (5 cm in length, 180° in range), cell sheets were harvested by a simple reduction in temperature to 20°C, and transplanted by endoscopy. Results: The transplanted cell sheets were able to adhere to and survive on the underlying muscle layers in the ulcer sites, providing an intact, stratified epithelium. Four weeks after surgery, complete wound healing, with no observable stenosis, was seen in the animals receiving autologous cell sheet transplantation. By contrast, noticeable fibrin mesh and host inflammation, consistent with the intermediate stages of wound healing, were observed in the control animals that received only ESD. Conclusions: These findings in a clinically relevant canine model show the effectiveness of a novel combined endoscopic approach for the potential treatment of oesophageal cancers that can effectively enhance wound healing and possibly prevent postoperative oesophageal stenosis.

Periodontal regeneration with multi-layered periodontal ligament-derived cell sheets in a canine model.

Periodontal regeneration has been challenged with chemical reagents and/or biological approaches, however, there is still no sufficient technique that can regenerate complete periodontium, including alveolar bone, cementum, and well-oriented collagen fibers. The purpose of this study was to examine multi-layered sheets of periodontal ligament (PDL)-derived cells for periodontal regeneration. Canine PDL cells were isolated enzymatically and expanded in vitro. The cell population contained cells capable of making single cell-derived colonies at an approximately 20% frequency. Expression of mRNA of periodontal marker genes, S100 calcium binding protein A4 and periostin, was observed. Alkaline phosphatase activity and gene expression of both osteoblastic/cementoblastic and periodontal markers were upregulated by osteoinductive medium. Then, three-layered PDL cell sheets supported with woven polyglycolic acid were transplanted to dental root surfaces having three-wall periodontal defects in an autologous manner, and bone defects were filled with porous beta-tricalcium phosphate. Cell sheet transplantation regenerated both new bone and cementum connecting with well-oriented collagen fibers, while only limited bone regeneration was observed in control group where cell sheet transplantation was eliminated. These results suggest that PDL cells have multiple differentiation properties to regenerate periodontal tissues comprising hard and soft tissues. PDL cell sheet transplantation should prove useful for periodontal regeneration in clinical settings.

Comparison of different tissue-derived stem cell sheets for periodontal regeneration in a canine 1-wall defect model.

Cytotherapeutic approaches have been investigated to overcome the limitations of existing procedures for periodontal regeneration. In this study, cell sheet transplantation was performed using three kinds of mesenchymal tissue (periodontal ligament, alveolar periosteum, and bone marrow)-derived cells to compare the differences between cell sources in a canine severe defect model (one-wall intrabony defect). Periodontal ligament cells (PDLCs), iliac bone marrow mesenchymal stromal cells (BMMSCs), and alveolar periosteal cells (APCs) were obtained from each dog; a total of four dogs were used. Three-layered cell sheets of each cell source supported with woven polyglycolic acid were autologously transplanted to the denuded root surface. One-wall intrabony defects were filled with a mixture of β-tricalcium phosphate (β-TCP) and collagen. Eight weeks after the transplantation, periodontal regeneration was significantly observed with both newly formed cementum and well-oriented PDL fibers more in the PDLC group than in the other groups. In addition, nerve filament was observed in the regenerated PDL tissue only in the PDLC group. The amount of alveolar bone regeneration was highest in the PDLC group, although it did not reach statistical significance among the groups. These results indicate that PDLC sheets combined with β-TCP/collagen scaffold serve as a promising tool for periodontal regeneration.

Fabrication of human oral mucosal epithelial cell sheets for treatment of esophageal ulceration by endoscopic submucosal dissection

BACKGROUND Esophageal stenosis is one of the major complications of aggressive endoscopic resection. Tissue-engineered epithelial cell grafts have demonstrated effectiveness in promoting re-epithelialization and suppressing inflammation causing esophageal scarring and stenosis after endoscopic submucosal dissection (ESD) in an animal model. OBJECTIVE To confirm the reproducibility and efficacy of a human oral mucosal epithelial cell (hOMEC) sheet cultured on temperature-responsive surface in conformity with Good Manufacturing Practice guidelines. DESIGN A preclinical study. SETTING Good Manufacturing Practice grade cell-processing center, animal laboratory. SUBJECTS Canine esophageal ulcer models, which were made by ESD. INTERVENTIONS Oral mucosal specimens were obtained from 7 healthy volunteers. MAIN OUTCOME MEASUREMENT Fabricated and transplanted hOMEC sheets were subjected to histological analysis. RESULTS The reproducibility of the fabrication of hOMEC sheets was confirmed. In this method, animal-derived materials such as 3T3 feeder layer and fetal bovine serum were successfully excluded from the culture condition. Furthermore, the environment of the culture room and safety cabinet in the cell-processing center was maintained for obtaining sterility assurances during the fabrication. Transplanted hOMEC sheets after ESD were observed to graft onto canine esophageal ulcer surfaces. LIMITATIONS Small number of subjects, animal model. CONCLUSIONS Cultured hOMEC sheets were fabricated without animal-derived materials and demonstrated efficacy as a medical device that promotes re-epithelialization of an esophageal ulcer after ESD.

Functional closure of visceral pleural defects by autologous tissue engineered cell sheets

OBJECTIVE The occurrence of intraoperative air leaks is an unavoidable complication during pulmonary surgeries. However, current surgical methods are generally ineffective in closing these visceral pleural defects, resulting in a decreased quality of life for patients. Here, we examined novel tissue engineered cell sheets for the closure of pleural defects in a porcine model. METHODS Skin biopsies were harvested from juvenile swine and tissue sheets composed of dermal fibroblasts were created using ex vivo culture on temperature-responsive dishes. After creating a visceral pleural injury model, the tissue engineered autologous dermal fibroblast sheets were transplanted directly to the defects without the use of sutures or additional adhesive agents, such as fibrin glue. RESULTS The tissue engineered autologous dermal fibroblast sheets attached directly to the lung surface providing an immediate seal against up to 25 cm H2O of airway pressure. Four weeks after transplantation, the dermal fibroblast sheets remained present on the pleural surface, providing permanent closure. The dermal fibroblast sheets were also responsive to changes in lung volume due to mechanical ventilation. No recurrences of air leaks were observed throughout the follow-up period. CONCLUSIONS This study presents the development of an effective sealant for visceral pleural defects using autologous cells that have the flexibility to respond to expansion and contraction during respiration.

Preparation of keratinocyte culture medium for the clinical applications of regenerative medicine.

Keratinocyte culture medium (KCM) has been used for the in vitro culture of keratinocytes and other types of epithelial cells, and the medium includes various ingredients. In this study, two modified KCMs were prepared. In the first, insulin, hydrocortisone and antibiotics that are normally included in KCM were replaced with clinically approved pharmaceutical agents, except transferrin and selenium; in the second, cholera toxin (CT) was replaced by L‐isoproterenol (ISO). The modified KCMs were then compared to conventional KCM containing laboratory‐grade reagents. Induced cell colony formations of canine oral mucosal epithelial cells cultured in both modified KCMs were found to be nearly equivalent to that in the control KCM, and there was no significant difference between the effect of CT and ISO. Canine oral mucosal cells proliferated to confluence in all three KCM formulations, with or without the use of 3T3 feeder layers. Cultured epithelial cells were harvested from temperature‐responsive culture surfaces as an intact cell sheet, and the immunohistochemical analysis of the sheets showed that p63 and cytokeratin were expressed in the epithelial cell sheets cultured in all KCMs. Eventually, in the modified KCM formula, fetal bovine serum was replaced by autologous human serum, and the formula was found to be able to fabricate human oral mucosal epithelial cell sheets. These results indicated that the modified KCM was equally efficient as conventional KCM in the fabrication of transplantable stratified epithelial cell sheets. Copyright

Fabrication and validation of autologous human oral mucosal epithelial cell sheets to prevent stenosis after esophageal endoscopic submucosal dissection.

Objectives: Human oral mucosal epithelial cells derived from 7 healthy volunteer donors were cultured in a clean room in a cell-processing center (CPC) according to good manufacturing practice guidelines. Cell culture and fabricated transplantable epithelial cell sheets were validated for treating ulcers after endoscopic mucosal dissection. Methods: The clonal growth and morphology of the human oral mucosal epithelial cells seeded on temperature-responsive surfaces were observed. During the cultivation, sterilization tests were performed to validate the environment in the CPC. To validate the purity and morphology of fabricated epithelial cell sheets, cell sheets harvested from temperature-responsive surfaces by temperature reduction were examined by histology and flow cytometry. Results: Human oral mucosal epithelial cells were successfully cultured and harvested as continuous cell sheets from temperature-responsive culture inserts without any animal-derived materials. During the cultivations, the sterile environment in the CPC was confirmed. The results of histological and flow cytometry analysis showed the high reproducibility of stratification and the purity of the fabricated human oral mucosal epithelial cell sheets. Conclusions: The method for fabricating epithelial cell sheets shown in this study was suitable for the validation for clinical trials and suggested usability of the fabricated cell sheets.

A novel method of culturing human oral mucosal epithelial cell sheet using post-mitotic human dermal fibroblast feeder cells and modified keratinocyte culture medium for ocular surface reconstruction

Background/aims To cultivate human oral mucosal epithelial cell sheets with post-mitotic human dermal fibroblast feeder cells and modified keratinocyte culture medium for ocular surface reconstruction. Methods Human oral mucosal epithelial cells obtained from three healthy volunteers were cultured with x-ray-treated dermal fibroblasts (fibroblast group) and NIH/3T3 feeder layers (3T3 group) on temperature-responsive culture dishes. Media were supplemented using clinically approved products. Colony-forming efficiency was determined in both groups. Histological and immunohistochemical analyses were performed for cell sheets. Cell viability and purity of cell sheets were evaluated by flow cytometry. Results Colony-forming efficiency in the fibroblast group was similar to that in the 3T3 group. All cell sheets were well stratified and harvested successfully. The expression patterns of keratin 1, 3/76, 4, 10, 12, 13, 15, ZO-1 and MUC16 were equivalent in both groups. The percentage of p63-positive cells in the fibroblast group (46.1±4.2%) was significantly higher than that in the 3T3 group (30.7±7.6%) (p=0.038, t test). The cell viability and purity were similar between the two groups. Conclusion This novel culture method using dermal fibroblasts and pharmaceutical agents provides a safe cell processing system without xenogenic feeder cells for ocular surface reconstruction.

Application of regenerative medical technology using tissue-engineered cell sheets for endoscopic submucosal dissection of esophageal neoplasms.

We have developed a technique for endoscopic transplantation of cultured autologous oral mucosal epithelial cell sheets to an esophageal ulcer following endoscopic submucosal dissection (ESD). The epithelial cell sheets successfully prevented esophageal stricture after ESD. Key technology is that epithelial cell sheets cultured from oral mucosal tissue and attached proteins can be harvested using cell sheet technology and can be transplanted to a wound site without the use of adhesive material. This regenerative procedure can promote the epithelialization of ulceration safely and effectively. In the near future, the development of advanced endoscopic treatment of regenerative medicine shows promise.

Prevention of esophageal strictures after endoscopic submucosal dissection

Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) have recently been accepted as less invasive methods for treating patients with early esophageal cancers such as squamous cell carcinoma and dysplasia of Barretts esophagus. However, the large defects in the esophageal mucosa often cause severe esophageal strictures, which dramatically reduce the patients quality of life. Although preventive endoscopic balloon dilatation can reduce dysphagia and the frequency of dilatation, other approaches are necessary to prevent esophageal strictures after ESD. This review describes several strategies for preventing esophageal strictures after ESD, with a particular focus on anti-inflammatory and tissue engineering approaches. The local injection of triamcinolone acetonide and other systemic steroid therapies are frequently used to prevent esophageal strictures after ESD. Tissue engineering approaches for preventing esophageal strictures have recently been applied in basic research studies. Scaffolds with temporary stents have been applied in five cases, and this technique has been shown to be safe and is anticipated to prevent esophageal strictures. Fabricated autologous oral mucosal epithelial cell sheets to cover the defective mucosa similarly to how commercially available skin products fabricated from epidermal cells are used for skin defects or in cases of intractable ulcers. Fabricated autologous oral-mucosal-epithelial cell sheets have already been shown to be safe.