Metabolomic Alteration of Oral Keratinocytes and Fibroblasts in Hypoxia.

The oxygen concentration in normal human tissue under physiologic conditions is lower than the atmospheric oxygen concentration. The more hypoxic condition has been observed in the cells with wound healing and cancer. Somatic stem cells reside in a hypoxic microenvironment in vivo and prefer hypoxic culture conditions in vitro. Oral mucosa contains tissue-specific stem cells, which is an excellent tissue source for regenerative medicine. For clinical usage, maintaining the stem cell in cultured cells is important. We previously reported that hypoxic culture conditions maintained primary oral keratinocytes in an undifferentiated and quiescent state and enhanced their clonogenicity. However, the metabolic mechanism of these cells is unclear. Stem cell biological and pathological findings have shown that metabolic reprogramming is important in hypoxic culture conditions, but there has been no report on oral mucosal keratinocytes and fibroblasts. Herein, we conducted metabolomic analyses of oral mucosal keratinocytes and fibroblasts under hypoxic conditions. Hypoxic oral keratinocytes and fibroblasts showed a drastic change of metabolite concentrations in urea cycle metabolites and polyamine pathways. The changes of metabolic profiles in glycolysis and the pentose phosphate pathway under hypoxic conditions in the oral keratinocytes were consistent with those of other somatic stem cells. The metabolic profiles in oral fibroblasts showed only little changes in any pathway under hypoxia except for a significant increase in the antioxidant 2-oxoglutaric acid. This report firstly provides the holistic changes of various metabolic pathways of hypoxic cultured oral keratinocytes and fibroblasts.

Effects of C-xylopyranoside derivative on epithelial regeneration in an in vitro 3D oral mucosa model.

Identifying substandard tissue-engineered oral mucosa grafts with a poor epithelium before clinical use is critical to ensure quality assurance/control in regenerative medicine, leading to success of grafting. This study investigated the effects of one of the C-xylopyranoside derivatives, ß-D-xylopyranoside-n-propane-2-one (XPP), on oral epithelial regeneration. Using a three-dimensional oral mucosa model, we analyzed changes of the epithelial structure, glycosaminoglycan (GAG) synthesis, the expression levels of basement membrane zone markers, and substrates of Akt/mTOR signaling. Compared with the control, 2 mM XPP treatment increased the mean and minimal epithelial thickness, and reduced the variation of epithelial thickness. It also stimulated expressions of decorin and syndecan-1 with change of GAG amount and/or composition, and enhanced the expressions of integrin α6, CD44, and Akt/mTOR signaling substrates. These findings suggest that XPP supplementation contributes to consistent epithelial regeneration. Moreover, upregulation of those markers may play a role in increasing the quality of the oral mucosal epithelium.

Severe destruction of the temporomandibular joint with complete resorption of the condyle associated with synovitis, acne, pustulosis, hyperostosis, and osteitis syndrome.

The synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome consists of a combination of inflammatory bone disorders and dermatologic pathology. Bone lesions as a form of diffuse sclerosing osteomyelitis in the mandible occur in the posterior body and ramus. Bone lesions rarely spread to the temporomandibular joint (TMJ) where ankylosis may result. Herein we present an unusual case of SAPHO syndrome with TMJ involvement in which severe destruction of the TMJ occurred. We observed an extension of the invasive soft tissue lesion into the infratemporal fossa from the TMJ with complete resorption of the condyle. In contrast to other previously reported cases, in our case the condyle was strongly suspected as the primary site of the bone lesion with subsequent extension to the ramus and infratemporal fossa. The destructive nature and related symptoms resembled a malignant tumor.

Distinct expression patterns and roles of aldehyde dehydrogenases in normal oral mucosa keratinocytes: differential inhibitory effects of a pharmacological inhibitor and RNAi-mediated knockdown on cellular phenotype and epithelial morphology.

Aldehyde dehydrogenases (ALDHs), enzymes responsible for detoxification and retinoic acid biosynthesis, are considered a potent functional stem cell marker of normal and malignant cells in many tissues. To date, however, there are no available data on ALDH distributions and functions in oral mucosa. This study aims to clarify the levels and types of ALDH expression using immunohistochemistry with accompanying mRNA expression as well as an ALDEFLUOR assay, and to assess phenotypic and histological changes after manipulation of the ALDH activity of oral keratinocytes to increase the potency of a tissue-engineered oral mucosa by a specific ALDH inhibitor, diethylaminobenzaldehyde (DEAB), together with small interfering RNA of ALDH1A3 and ALDH3A1. Results showed the mRNA and cytoplasmic protein expression of ALDH1A3 and ALDH3A1 to be mostly localized in the upper suprabasal layer although no ALDH1A1 immunoreaction was detected throughout the epithelium. Oral keratinocytes with high ALDH activity exhibited a profile of differentiating cells. By pharmacological inhibition, the phenotypic analysis revealed the proliferating cell-population shifting to a more quiescent state compared with untreated cells. Furthermore, a well-structured epithelial layer showing a normal differentiation pattern and a decrease in Ki-67 immunopositive basal cells was developed by DEAB incubation, suggesting a slower turnover rate efficient to maintain undifferentiated cells. Histological findings of a regenerated oral epithelium by ALDH1A3 siRNA were similar to those when treated with DEAB while ALDH3A1 siRNA eradicated the epithelial regenerative capacity. These observations suggest the effects of phenotypic and morphological alterations by DEAB on oral keratinocytes are mainly consequent to the inhibition of ALDH1A3 activity.

Construction and characterization of a tissue-engineered oral mucosa equivalent based on a chitosan-fish scale collagen composite.

This study was designed to (1) assess the in vitro biocompatibility of a chitosan-collagen composite scaffold (C3) constructed by blending commercial chitosan and tilapia scale collagen with oral mucosa keratinocytes, (2) histologically and immunohistochemically characterize an ex vivo-produced oral mucosa equivalent constructed using the C3 (EVPOME-C), and (3) compare EVPOME-C with oral mucosa constructs utilizing AlloDerm® (EVPOME-A), BioMend® Extend™ (EVPOME-B), and native oral mucosa. C3 scaffold had a well-developed fibril network and a sufficiently small porosity to prevent keratinocytes from growing inside the scaffold after cell-seeding. The EVPOME oral mucosa constructs were fabricated in a chemically defined culture system. After culture at an air-liquid interface, EVPOME-C and EVPOME-B had multilayered epithelium with keratinization, while EVPOME-A had a more organized stratified epithelium. Ki-67 and p63 immunolabeled cells in the basal layer of all EVPOMEs suggested a regenerative ability. Compared with native oral mucosa, the keratin 15 and 10/13 expression patterns in all EVPOMEs showed a less-organized differentiation pattern. In contrast to the ß1-integrin and laminin distribution in EVPOME-A and native oral mucosa, the subcellular deposition in EVPOME-C and EVPOME-B indicated that complete basement membrane formation failed. These findings demonstrated that C3 has a potential application for epithelial tissue engineering and provides a new potential therapeutic device for oral mucosa regenerative medicine.

Zoledronic acid induces S-phase arrest via a DNA damage response in normal human oral keratinocytes.

OBJECTIVE: This study aimed to clarify the effects of zoledronic acid (ZOL) on human primary oral mucosal keratinocytes growing in a monolayer culture and on a tissue-engineered oral mucosal construct. DESIGN: Changes in the viability and proliferation of oral keratinocytes incubated with ZOL were measured. Following treatment with 10 µM ZOL, histological examinations and immunohistochemical analyses for Ki-67, Geminin, and phospho-histone (γ)-H2A.X were performed on tissue-engineered oral mucosa. Cell cycle distribution and the degree of apoptosis were also measured by flow cytometry. Additionally, we measured the expression of cell cycle regulatory proteins as well as phospho-Chk1 and -Chk2. RESULTS: ZOL treatment suppressed cell viability and proliferation in a dose-dependent manner. Compared with untreated tissue-engineered oral mucosa, ZOL treatment resulted in a thinner epithelium in which the basal cells appeared less-organised. This is consistent with the observed significant reduction in the Ki-67 labelling index. In contrast, the Geminin labelling index was significantly higher than that in the untreated sample. In spite of the presence of a few apoptotic cells, ZOL induced an arrest in S-phase, which was confirmed by our observed alterations in the expression levels of cyclin A, B1, p27(KIP1), Rb and phospho-Rb. When the proteasome inhibitor MG132 was added to the ZOL-treated cells, we observed a partial restoration of the expression of cyclin A, cyclin B1, and p27(KIP1). Expression of phospho-Chk1 was detected, and a significant increase in the labelling index of γ-H2A.X was also seen. CONCLUSIONS: These results indicate that a 10-µM ZOL treatment induces a DNA damage response in oral keratinocytes that activates the ubiquitin-mediated proteolysis of cell cycle regulators, resulting in cell cycle arrest and repressive effects on cell viability, proliferation, and epithelial turnover.