Transplantation of a human induced pluripotent stem cell-derived airway epithelial cell sheet into the middle ear of rats

[Introduction] Early postoperative regeneration of the middle ear mucosa is essential for the prevention of postoperative refractory otitis media and recurrent cholesteatoma. As a means for intractable otitis media management, we focused on human induced pluripotent stem cell (hiPSC)-derived airway epithelial cells (AECs), which have been used in upper airway mucosal regeneration and transplantation therapy. In this study, we transplanted hiPSC-derived AECs into the middle ear of immunodeficient rats. [Methods] Following the preparation of AEC sheets from hiPSCs, the bilateral middle ear mucosa of X-linked severe combined immunodeficient rats was scraped, and the AEC sheets were transplanted in the ears unilaterally. [Results] Human nuclear antigen (HNA)-positive ciliated cells were observed on the transplanted side of the middle ear cavity surface in three of six rats in the 1-week postoperative group and in three of eight rats in the 2-week postoperative group. No HNA-positive cells were found on the control side. The percentage of HNA-positive ciliated cells in the transplanted areas increased in the 2-week postoperative group compared with the 1-week group, suggesting survival of hiPSC-derived AECs. Additionally, HNA-positive ciliated cells were mainly located at sites where the original ciliated cells were localized. Immunohistochemical analysis showed that the transplanted AECs contained cytokeratin 5- and mucin 5AC-positive cells, indicating that both basal cells and goblet cells had regenerated within the middle ear cavity. [Conclusions] The results of this study are an important first step in the establishment of a novel transplantation therapy for chronic otitis media

Development of a nasal mucosa-removal model for evaluating cell therapy

Introduction: Endoscopic sinus surgery is an effective surgical procedure for treating chronic sinusitis; however, extensive exposure of the bone in the nasal cavity can result in permanent disability postoperatively. Particularly, closure of the sinus drainage pathway due to bone hyperplasia associated with bone exposure can trigger the recurrence of sinusitis. It is essential to regenerate the nasal mucosa after surgery to avoid bone hyperplasia. Regenerative medicine, including cell therapy, could be one of the leading options for nasal mucosa regeneration. To date, there is a lack of effective models for evaluating treatments for prevention of bone hyperplasia that occurs after sinus surgery. The purpose of this study was to develop a model of nasal mucosal removal to evaluate cellular therapies. Methods: The model was created in rabbits, a species with a wide nasal structure, and was generated by approaching the maxillary sinus from the nasal bone side and solely removing the maxillary sinus mucosa without destroying the structures in the nasal cavity. Adipose-derived mesenchymal stromal cell sheets prepared in temperature-responsive cell culture dishes were examined for the effect of transplantation in the animal model. Intranasal evaluation was assessed by micro-computed tomography and tissue staining. Results: Significant bone hyperplasia in the maxillary sinus occurred on the side of mucosal removal, and no bone hyperplasia occurred in the control sham side in the same rabbits on postoperative day 28. Bone hyperplasia was observed over a short time period, with the presence of bone hyperplasia in the maxillary sinus on day 14 and calcification of the bone on day 28. The adipose-derived mesenchymal stromal cell (ADSC) sheet was transplantable in a nasal mucosa-removal model. No significant differences in bone hyperplasia were found between the transplantation side and the sham side in terms of the effect of transplantation of the ADSC sheet; however, bone hyperplasia tended to be suppressed on the transplantation side. Conclusions: This animal model is simple, highly reproducible, and does not require special equipment or drugs. In addition, this model can be used for various therapeutic interventions, including cell therapy. The presence or absence of the nasal mucosa affects bone remodeling, which highlights the importance of regeneration of the nasal mucosa. In the nasal mucosal regeneration therapy, the ADSC sheet had an inhibitory effect on bone hyperplasia. The nasal mucosa-removal model allows observation of conditions associated with nasal mucosa removal and evaluation of the effectiveness of cell therapy

Explant culture of oral mucosal epithelial cells for fabricating transplantable epithelial cell sheet

Introduction: Carrier-free autologous mucosal epithelial cell sheets have been clinically utilized as a cell therapy for various epithelial disorders. Fabrication of a transplantable oral mucosal epithelial cell sheet without mouse feeder layers requires a higher seeding density than that of a sheet with mouse feeder layer culture; therefore, a large amount of donor mucosal tissue is needed. However, cell grafts co-cultured with mouse feeder layers are classified by the US Food and Drug Administration (FDA) as xenogeneic products. The goal of this study was to evaluate the utility of oral mucosal epithelial cells expanded by primary explant culture for the fabrication of an adequate number of transplantable epithelial cell sheets without mouse feeder layers. Methods: Small fragments derived from minced oral mucosal tissue were placed into culture dishes for primary explant culture in keratinocyte culture medium. After primary explant culture, the outgrown cells were treated with trypsin-EDTA and were seeded on a temperature-responsive cell culture insert. After subculture, the cultured cells were harvested as a confluent cell sheet from the culture vessel by temperature reduction. Results: Carrier-free human oral mucosal epithelial cell sheets were fabricated in all human cases, and autologous transplantation of the harvested cell sheets showed rapid epithelial regeneration to cover epithelial defects in a rabbit model. The explant culture method, involving the use of small fragments for primary culture, was sufficient for preparing a large number of mucosal epithelial cells without mouse feeder layers. Moreover, oral mucosal epithelial cells derived from the primary explant culture after cryopreservation allowed for the fabrication of cell sheets. Conclusions: This method for fabricating transplantable oral mucosal epithelial cell sheets is an attractive technique for regenerative medicine. It offers a patient-friendly manufacturing method in which a small amount of biopsy material from the patient represents a sufficient epithelial cell source, and a manufacturing plan for preparing cell grafts can be easily tailored. Keywords: Cell therapy, Regenerative medicine, A small amount of biopsy, A sufficient epithelial cell source, Autologous transplantation, Without mouse feeder layer

Effect of basic fibroblast growth factor with collagen/gelatin fixture in a rabbit model of nasal septum perforation

Introduction: The treatment of nasal septum perforation solely by surgical intervention presents significant challenges. This study evaluated the effect of basic fibroblast growth factor (bFGF) in combination with collagen/gelatin on wound healing of nasal septum perforation in a rabbit animal model. Methods: A nasal septum perforation rabbit model was created. bFGF was added to a collagen/gelatin fixture and placed adjacent to the perforation, which is a complete defect. The rabbits were divided into three groups: the sham group that underwent the surgical procedure only, bFGF (−) group that received collagen/gelatin fixture without bFGF, and bFGF(+) group that received collagen/gelatin fixture with bFGF. The dimensions of the perforations were measured after 4 weeks, and the septum was subjected to histological examination. Results: All perforations remained open in the sham group (closure rate: 20.4%–83.1%). The closure rates of the bFGF(−) and bFGF(+) groups were 49.4%–68.8% and 72.7%–100%, respectively. No significant difference was noted in the closure rates between the sham and bFGF(−) groups; however, significant differences were observed between the sham and bFGF(+) groups, and the bFGF(−) and bFGF(+) groups (p < 0.05), indicating that bFGF promoted perforation closure. Conclusions: The study demonstrated that bFGF with collagen/gelatin carrier promoted wound healing in a rabbit model of nasal septum perforation