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.

Preclinical assessment of transplantable human nasal mucosal epithelial cell sheets.

INTRODUCTION: We previously reported a new cell transplantation therapy for patients with intractable otitis media using autologous nasal mucosal epithelial cell sheets, manufactured using temperature-responsive cell culture inserts. The current study aimed to verify whether the transplantable cell sheets could be manufactured for application in clinical trials, according to standard operational procedures (SOP), in a cell processing facility (CPF). METHODS: Human nasal mucosal epithelial cells from four volunteer donors were aseptically cultured and transplantable cell sheets successfully manufactured, with reproducibility, using temperature-responsive cell culture inserts in the CPF. During the manufacture of cell sheets, the CPF environment was confirmed to be aseptic by sterilization tests. Purity of the cell sheets was confirmed by histological analysis and flow cytometry. Both safety and quality of the human nasal mucosal epithelial cell sheets were validated. RESULTS: The cultured and manipulated human nasal mucosal epithelial cells showed no evidence of malignant transformation in vitro. The study confirmed the safety and suitability of the manufactured human nasal mucosal epithelial cell sheets for use in clinical trials. CONCLUSIONS: The results led to the establishment of a coherent system in which transplantation could be achieved smoothly.

ROCK inhibitor combined with Ca2+ controls the myosin II activation and optimizes human nasal epithelial cell sheets.

The proliferation and differentiation of cultured epithelial cells may be modified by Rho-associated kinase (ROCK) inhibition and extracellular Ca2+ concentration. However, it was not known whether a combination would influence the behavior of cultured epithelial cells through changes in the phosphorylation of non-muscle myosin light chain II (MLC). Here we show that the combination of ROCK inhibition with Ca2+ elevation regulated the phosphorylation of MLC and improved both cell expansion and cell-cell adhesion during the culture of human nasal mucosal epithelial cell sheets. During explant culture, Ca2+ enhanced the adhesion of nasal mucosal tissue, while ROCK inhibition downregulated MLC phosphorylation and promoted cell proliferation. During cell sheet culture, an elevation of extracellular Ca2+ promoted MLC phosphorylation and formation of cell-cell junctions, allowing the harvesting of cell sheets without collapse. Moreover, an in vitro grafting assay revealed that ROCK inhibition increased the expansion of cell sheets three-fold (an effect maintained when Ca2+ was also elevated), implying better wound healing potential. We suggest that combining ROCK inhibition with elevation of Ca2+ could facilitate the fabrication of many types of cell graft.

Efficient preparation of human and mouse CD1d proteins using silkworm baculovirus expression system.

CD1d is a major histocompatibility complex (MHC) class I-like glycoprotein and binds to glycolipid antigens that are recognized by natural killer T (NKT) cells. To date, our understanding of the structural basis for glycolipid binding and receptor recognition of CD1d is still limited. Here, we established a preparation method for the ectodomain of human and mouse CD1d using a silkworm-baculovirus expression system. The co-expression of human and mouse CD1d and ß2-microglobulin (ß2m) in the silkworm-baculovirus system was successful, but the yield of human CD1d was low. A construct of human CD1d fused with ß2m via a flexible GS linker as a single polypeptide was prepared to improve protein yield. The production of this single-chained complex was higher (50 µg/larva) than that of the co-expression complex. Furthermore, differential scanning calorimetry revealed that the linker made the CD1d complex more stable and homogenous. These results suggest that the silkworm-baculovirus expression system is useful for structural and biophysical studies of CD1d in several aspects including low cost, easy handling, biohazard-free, rapid, and high yielding.

Analysis of human nasal mucosal cell sheets fabricated using transported tissue and blood specimens.

Previously, we succeeded in transplanting autologous nasal mucosal cell sheets in the middle ears of 5 patients, who underwent cholesteatoma resection, which prevents recurrence of cholesteatoma in clinical settings. Current good manufacturing practice (GMP) standards for human cell cultivation requires the establishment of cell processing centers (CPC) which act as germ-free facilities. However, due to practical difficulties involved in establishing and maintaining such facilities at each individual hospital, a functional transport system is felt to be needed for the continuation of effective regenerative therapy. In the current study, nasal mucosal tissue and autologous blood obtained from 3 human volunteers were transported for over 3 h. Disinfected nasal tissues were cultured using keratinocyte culture medium, which included autologous serum prepared from blood. After 24 d, cultured nasal mucosal cells were transported for over 3 h and subsequently assessed for cell number, viability and purity. Moreover, CK4, CK8, and CK18 were analyzed the suitability of these nasal mucosal cell sheets for middle ear regenerative therapy. Overall, we confirmed that nasal mucosal cell sheets can be fabricated using transported nasal mucosal tissue and blood. This study would be contribute to establish a new regenerative therapy for clinical application, accompanied with transportation between companies and hospitals.

Oral keratinocyte-derived exosomes regulate proliferation of fibroblasts and epithelial cells.

Extracellular vesicles (EVs), including exosomes, are small membrane-bound particles released by cells. From a therapeutic point of view, EVs can often convey similar biological function as their parent cell. Grafts originating from oral mucosa have frequently been used in regenerative medicine, and we have previously described the use of oral cell sheets to prevent stricture formation of the esophagus. Further, we recently found that exosomes derived from these cell sheets have pro-regenerative effect on skin wound healing. Here, we have isolated exosomes from conditioned media from oral keratinocyte ("OKEx") and dermal fibroblast ("FEx") cultures. The exosomes were probed for classical EV-markers by western blot (CD9, annexin V and Flotillin-1), FEx were positive for all markers while OKEx were positive only for CD9. Tunable resistive pulse sensing indicated a mean size of around 110 nm and transmission electron microscopy showed a spherical morphology, for both groups. After fluorescent labelling, we studied the uptake of exosomes co-cultured with fibroblasts or keratinocytes. Signal from OKEx could be detected after 90 min, and signal could be detected in all groups after 16 h. Finally we studied the exosomes' modulation of cell proliferation. Both groups suppressed proliferation of healthy keratinocyte and fibroblasts, at some doses to similar levels as dexamethasone (a drug commonly used to prevent stricture formation). In contrast, the exosomes also suppressed the proliferation of the carcinoma cell line TR146, while dexamethasone had no effect. In conclusion, we believe that exosome-signaling might be one of the mode-of-actions of cell sheet-therapy for stricture prevention.

Exosomes derived from clinical-grade oral mucosal epithelial cell sheets promote wound healing.

The oral mucosa exhibits unique regenerative properties, sometimes referred to as foetal-like wound healing. Researchers from our institute have used sheets of oral mucosa epithelial cells (OMECs) for regenerative medicine applications including cornea replacement and oesophageal epithelial regeneration for stricture prevention. Here, we have isolated exosomes from clinical-grade production of OMEC sheets from healthy human donors (n = 8), aiming to evaluate the clinical potential of the exosomes to stimulate epithelial regeneration and to improve understanding of the mode-of-action of the cells. Exosomes were isolated from conditioned (cExo) and non-conditioned (ncExo) media. Characterization was performed using Western blot for common exosomal-markers: CD9 and flotillin were positive while annexin V, EpCam and contaminating marker GRP94 were negative. Nanoparticle tracking analysis revealed a diameter of ~120 nm and transmission electron microscopy showed a corresponding size and spherical appearance. Human skin fibroblasts exposed to exosomes showed dose-dependent reduction of proliferation and a considerable increase of growth factor gene expression (HGF, VEGFA, FGF2 and CTGF). The results were similar for both groups, but with a trend towards a larger effect from cExo. To study adhesion, fluorescently labelled exosomes were topically applied to pig oesophageal wound-beds ex vivo and subsequently washed. Positive signal could be detected after as little as 1 min of adhesion, but increased adhesion time produced a stronger signal. Next, labelled exosomes were added to full-thickness skin wounds in rats and signal was detected up to 5 days after application. cExo significantly reduced the wound size at days 6 and 17. In conclusion, exosomes from OMEC sheets showed pro-regenerative effects on skin wound healing. This is the first time that the healing capacity of the oral mucosa is studied from an exosome perspective. These findings might lead to a combinational therapy of cell sheets and exosomes for future patients with early oesophageal cancer.

The role of ADAM-like decysin 1 in non-eosinophilic chronic rhinosinusitis with nasal polyps.

BACKGROUND: Chronic rhinosinusitis with nasal polyps (CRSwNP) is classified into two subtypes: eosinophilic (ECRSwNP) and non-eosinophilic (NECRSwNP). Although the inflammatory patterns of ECRSwNP have been elucidated, NECRSwNP is poorly understood. AIMS/OBJECTIVES: The metalloproteinase ADAM-like decysin 1 (ADAMDEC1) has been reported to play a role in the early stages of the inflammatory response. We investigated the role of ADAMDEC1 in the pathogenesis of CRSwNP. MATERIAL AND METHODS: We compared ADAMDEC1 expression in nasal polyp tissue from CRS patients using immunohistochemistry and RT-qPCR. Macrophages were cultured and ADAMDEC1 expression was determined at baseline and after exposure to lipopolysaccharide (LPS). RESULTS: ADAMDEC1 was virtually undetectable in tissues from control patients but was highly expressed in the NECRSwNP group compared with the ECRSwNP group. In nasal polyp tissues, ADAMDEC1 was expressed by CD68-positive cells, with a positive correlation between ADAMDEC1-positive and CD68-positive cells, and also between ADAMDEC1 and CD68 mRNA levels. Furthermore, stimulation of monocyte-derived macrophages with LPS induced ADAMDEC1 expression. CONCLUSIONS AND SIGNIFICANCE: This study demonstrates that ADAMDEC1 is involved in the pathogenesis of NECRSwNP, and also bacterial endotoxin signalling in macrophages; however, the underlying mechanism remains to be elucidated.

Oral epithelial cell sheets engraftment for esophageal strictures after endoscopic submucosal dissection of squamous cell carcinoma and airplane transportation.

Endoscopic submucosal dissection (ESD) permits en bloc removal of superficial oesophageal squamous cell carcinoma (ESCC). However, post-procedure stricture is common after ESD for widespread tumours, and multiple endoscopic balloon dilation (EBD) procedures are required. We aimed to evaluate the safety and effectiveness of endoscopic transplantation of tissue-engineered autologous oral mucosal epithelial cell sheets that had been transported by air over a distance of 1200 km in controlling postprocedural oesophageal stricture. Ten patients who underwent complete circular or semicircular ESD for ESCC were transplanted with cell sheets. The safety of the entire process including cell sheet preparation, transport, ESD and cell sheet transplantation was assessed. The incidence of oesophageal stricture, number of EBD sessions, and time until epithelialization were investigated. Each ESD was successfully performed, with subsequent cell sheet engrafting carried out safely. Following cell sheet transplantation, the luminal stenosis rate was 40%, while the median number of EBD sessions was 0. The median post-ESD ulcer healing period was rather short at 36 days. There were no significant complications at any stage of the process. Cell sheet transplantation and preparation at distant sites and transportation by air could be a safe and promising regenerative medicine technology.

Brush biopsy of human oral mucosal epithelial cells as a quality control of the cell source for fabrication of transplantable epithelial cell sheets for regenerative medicine.

Autologous oral mucosal epithelial cell sheets have been used for treating epithelial defects such as cornea and esophagus. The cell source of patients' oral mucosal epithelial cell sheet should be examined in normality because it has individual difference. In this study, oral mucosal epithelial cells were less invasively collected by brush biopsy from the buccal, gingival, labial, and palate mucosa of four healthy volunteer donors without anesthesia, and analyzed the keratin expressions by western blotting and the obtained results were compared with those by immunohistochemistry of each of the native tissues. All of the oral mucosal epithelial cells expressed keratin 4 (K4) and K13, which were mucosal stratified squamous epithelial cell markers. K1 and K10, keratinized epithelial cell markers, were also detected in keratinized tissues such as gingival and palate mucosa. The markers of epithelial basal cells such as p63 and K15 were not detected by brush biopsy-western blotting. Although this method does not include basal layers of oral mucosa, protein expressions of upper layer of lesion area are different from normal. Therefore, brush biopsy-western blotting was extremely less invasive and would contribute to quality control of the fabrication of autologous oral mucosal epithelial cell sheets.

How to prevent contamination with Candida albicans during the fabrication of transplantable oral mucosal epithelial cell sheets.

We have utilized patients' own oral mucosa as a cell source for the fabrication of transplantable epithelial cell sheets to treat limbal stem cell deficiency and mucosal defects after endoscopic submucosal dissection of esophageal cancer. Because there are abundant microbiotas in the human oral cavity, the oral mucosa was sterilized and 40 µg/mL gentamicin and 0.27 µg/mL amphotericin B were added to the culture medium in our protocol. Although an oral surgeon carefully checked each patient's oral cavity and although candidiasis was not observed before taking the biopsy, contamination with Candida albicans (C. albicans) was detected in the conditioned medium during cell sheet fabrication. After adding 1 µg/mL amphotericin B to the transportation medium during transport from Nagasaki University Hospital to Tokyo Women's Medical University, which are 1200 km apart, no proliferation of C. albicans was observed. These results indicated that the supplementation of transportation medium with antimycotics would be useful for preventing contamination with C. albicans derived from the oral mucosa without hampering cell proliferation.

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 Barrett's esophagus. However, the large defects in the esophageal mucosa often cause severe esophageal strictures, which dramatically reduce the patient's 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.