Leptin promotes wound healing in the skin.

INTRODUCTION: Leptin, a 16 kDa anti-obesity hormone, exhibits various physiological properties. Interestingly, skin wound healing was proven to delay in leptin-deficient ob/ob mice. However, little is known on the mechanisms of this phenomenon. In this study, we attempted to elucidate a role of leptin in wound healing of skin. METHODS: Immunohistochemical analysis was performed to confirm the expression of the leptin receptor (Ob-R) in human and mouse skin. Leptin was topically administered to chemical wounds created in mouse back skin along with sustained-release absorbable hydrogel. The process of wound repair was histologically observed and the area of ulceration was measured over time. The effect of leptin on the proliferation, differentiation and migration of human epidermal keratinocytes was investigated. RESULTS: Ob-R was expressed in epidermal cells of human and mouse skin. Topical administration of leptin significantly promoted wound healing. Histological analysis showed more blood vessels in the dermal connective tissues in the leptin-treated group. The proliferation, differentiation/function and migration of human epidermal keratinocytes were enhanced by exogenous leptin. CONCLUSION: Topically administered leptin was proven to promote wound healing in the skin by accelerating proliferation, differentiation/function and migration of epidermal keratinocytes and enhancing angiogenesis around the wounded area. These results strongly suggest that topical administration of leptin may be useful as a treatment to promote wound healing in the skin.

Leptin promotes wound healing in the oral mucosa.

INTRODUCTION: Leptin, a 16 kDa circulating anti-obesity hormone, exhibits many physiological properties. Recently, leptin was isolated from saliva; however, its function in the oral cavity is still unclear. In this study, we investigated the physiological role of leptin in the oral cavity by focusing on its effect on wound healing in the oral mucosa. METHODS: Immunohistochemical analysis was used to examine the expression of the leptin receptor (Ob-R) in human/rabbit oral mucosa. To investigate the effect of leptin on wound healing in the oral mucosa, chemical wounds were created in rabbit oral mucosa, and leptin was topically administered to the wound. The process of wound repair was histologically observed and quantitatively analyzed by measuring the area of ulceration and the duration required for complete healing. The effect of leptin on the proliferation, differentiation and migration of human oral mucosal epithelial cells (RT7 cells) was investigated using crystal violet staining, reverse transcription polymerase chain reaction (RT-PCR) and a wound healing assay, respectively. RESULTS: Ob-R was expressed in spinous/granular cells in the epithelial tissue and vascular endothelial cells in the subepithelial connective tissue of the oral mucosa. Topical administration of leptin significantly promoted wound healing and shortened the duration required for complete healing. Histological analysis of gingival tissue beneath the ulceration showed a denser distribution of blood vessels in the leptin-treated group. Although the proliferation and differentiation of RT7 cells were not affected by leptin, the migration of these cells was accelerated in the presence of leptin. CONCLUSION: Topically administered leptin was shown to promote wound healing in the oral mucosa by accelerating epithelial cell migration and enhancing angiogenesis around the wounded area. These results strongly suggest that topical administration of leptin may be useful as a treatment to promote wound healing in the oral mucosa.

Nerve growth factor increases electrical activity of neural cells derived from murine bone marrow stromal cells.

OBJECTIVE: Nerve growth factor (NGF) triggers long-term neuronal excitability. We examined its effect on murine bone marrow stromal cells (BMSC)-derived neurons. METHODS: With an optimal differentiation protocol, BMSCs were differentiated into neurons in culture. To confirm the probability of differentiation of BMSC into neuron, the expression of neuronal marker protein, neurofilament, was examined by immunocytochemistry. To examine the electrophysiological properties of BMSC-derived neurons, the field potentials were recorded either from nontreated (control) BMSC-derived neurons or from BMSC-derived neurons after the treatment with NGF by using extracellular recording techniques. RESULTS: Most BMSC-derived neurons showed spontaneous discharges whose amplitudes were up to 2 mV. When NGF at a concentration of 100 ng/ml was applied to BMSC-derived neurons, the amplitudes of discrete field potentials were gradually enlarged within 1 min after NGF application and peaked 3 min later (20-fold the size of control). However, the enlargement of the amplitudes of field potentials almost disappeared 5 min after NGF application. CONCLUSION: This finding indicates that neuronal cells derived from murine BMSCs generate discrete field potential activities spontaneously and that NGF has the effect of enlarging transient, but not sustained, electrical activity of BMSC-derived neurons.

Leptin and vascular endothelial growth factor regulate angiogenesis in tooth germs.

Leptin, a 16 kDa non-glycolated polypeptide of 146 amino acids produced by the ob gene, has a variety of physiological roles not only in lipid metabolism, hematopoiesis, thermogenesis and ovarian function, but also in angiogenesis. This study focuses to investigate the possibility that leptin, as an angiogenic factor, may regulate the angiogenesis during tooth development. We firstly studied the expression of leptin and vascular endothelial growth factor (VEGF) during tooth development immunohistochemically. This investigation revealed that leptin is expressed in ameloblasts, odontoblasts, dental papilla cells and stratum intermedium cells. This expression pattern was similar to that of VEGF, one of the most potent angiogenic factors. Interestingly, more leptin-positive cells were observed in the upper third portion of dental papilla, which is closest to odontoblastic layer, compared to middle and lower thirds. Moreover, in the dental papilla, more CD31 and/or CD34-positive vascular endothelial cells were observed in the vicinity of ameloblasts and odontoblasts expressing leptin and VEGF. These findings strongly suggest that ameloblasts, odontoblasts and dental papilla cells induce the angiogenesis in tooth germs by secretion of leptin as well as VEGF.

Possible involvement of maspin in tooth development.

Maspin is a 42 kDa serine protease inhibitor that possesses tumor suppressive and anti-angiogenic activities. Despite of a huge amount of data concerning the expression pattern of maspin in various tissues and its relevance to the biological properties of a variety of human cancer cells, little is known on the maspin expression in skeletal and tooth tissues. Recently, we reported that maspin may play an important role in extracellular matrix formation in bone by enhancing the accumulation of latent TGF-ß in the extracellular matrix. This study was performed to elucidate the possible role of maspin in tooth development. First, an immunohistochemical analysis for human tooth germs at the late bell stage showed the expression of maspin by active ameloblasts and odontoblasts that were forming enamel and dentin, respectively. During rat tooth development, maspin expression was observed for the first time in inner and outer enamel epithelial cells and dental papilla cells at early bell stage. The neutralizing anti-maspin antibody inhibited the proper dental tissue formation in organ cultures of mandibular first molars obtained from 21-day-old rat embryos. In addition, the proliferation of HAT-7 cells, a rat odontogenic epithelial cell line, and human dental papilla cells were suppressed in a dose-dependent manner with anti-maspin antibody. Moreover, RT-PCR analysis showed that the expression of mRNA for tooth-related genes including dentin matrix protein 1, dentin sialophosphoprotein and osteopontin in human dental papilla cells was inhibited when treated with anti-maspin antibody. These findings suggest that maspin expressed in ameloblasts and odontoblasts plays an important physiological role in tooth development through the regulation of matrix formation in dental tissues.

Possible involvement of melatonin in tooth development: expression of melatonin 1a receptor in human and mouse tooth germs.

Melatonin is known to regulate a variety of physiological processes including control of circadian rhythms, regulation of seasonal reproductive function, regulation of body temperature, free radical scavenging, and so forth. Accumulating evidence from in vitro and in vivo experiments has also suggested that melatonin may have an influence on skeletal growth and bone formation. However, little is known about the effects of melatonin on tooth development and growth, which thus remain to be elucidated. This study was performed to examine the possibility that melatonin might exert its influence on tooth development as well as skeletal growth. Immunohistochemical analysis revealed that melatonin 1a receptor (Mel1aR) was expressed in secretory ameloblasts, the cells of the stratum intermedium and stellate reticulum, external dental epithelial cells, odontoblasts, and dental sac cells. Reverse transcription-polymerase chain reaction and Western blot analysis showed that HAT-7, a rat dental epithelial cell line, expressed Mel1aR and its expression levels increased after the cells reached confluence. These results strongly suggest that melatonin may play a physiological role in tooth development/growth by regulating the cellular function of odontogenic cells in tooth germs.

High-dose-rate brachytherapy for patients with maxillary gingival carcinoma using a novel customized intraoral mold technique.

OBJECTIVE: The purpose of this study was to introduce a novel customized intraoral mold treatment for maxillary gingival carcinoma (UGC). STUDY DESIGN: Two patients with UGC were treated as salvage therapy using this technique. The mold was designed to keep normal soft tissues adjacent to the tumor away from the radioactive source as much as possible, and it was shielded by lead. The radiation dose on the buccal mucosa and tongue was measured at the inner and outer surfaces of the intraoral mold before starting high-dose-rate brachytherapy by the remote afterloading system, and was reduced to almost one tenth. RESULTS: The patient had no recurrence and no severe adverse effects on the normal soft tissue adjacent to the tumor until the end of the follow-up period. CONCLUSION: High-dose-rate brachytherapy using the novel customized intraoral mold might be a treatment option of not only salvage therapy, but definitive therapy of UGC.

Possible involvement of stem cell factor and endothelin-1 in the emergence of pigmented squamous cell carcinoma in oral mucosa.

We present here the clinical, morphological and immunohistochemical features of a pigmented squamous cell carcinoma (SCC) in the oral mucosa of the hard palate of a 76-year-old Japanese man. He underwent a partial resection of the maxilla subsequent to radiotherapy. The tumor was typical, moderately well-differentiated SCC but had many melanocytes (melanocytosis) within it. Immunohistochemical analysis for stem cell factor (SCF) and endothelin-1, both of which are known to stimulate proliferation and differentiation of melanocytes, revealed prominent expression of both factors in the neoplastic squamous cells of the pigmented SCC, while the non-pigmented oral SCC showed little sign of either factor. These findings strongly suggest that SCF and endothelin-1 secreted by neoplasmic squamous cells are involved in the emergence of a rare variant of oral SCC.

Maspin is involved in bone matrix maturation by enhancing the accumulation of latent TGF-beta.

UNLABELLED: Maspin, a serine protease inhibitor, is expressed by formative osteoblasts. The repression of maspin expression in osteoblastic cells decreased the level of latent TGF-beta in the extracellular matrix, whereas the overexpression of maspin increased latent TGF-beta. These findings suggest that maspin plays an important role in bone matrix formation, particularly in the accumulation of latent TGF-beta. INTRODUCTION: Maspin is a serine protease inhibitor that exhibits tumor suppressive and anti-angiogenic activities. This study was performed to elucidate a possible role for maspin in bone formation. MATERIALS AND METHODS: We performed immunohistochemical analysis of the expression of maspin during endochondral ossification. We evaluated the expression of maspin mRNA and protein in ROS 17/2.8 cells and primary rat osteoblastic cells by RT-PCR, immunocytochemistry, and Western blot analysis. We also examined the accumulation of TGF-beta in the extracellular matrix of cultured ROS 17/2.8 cells after transfection with vectors expressing either maspin or maspin antisense. RESULTS: We observed expression of maspin by active osteoblasts in vivo. Rat osteoblastic cells also expressed maspin mRNA and protein in vitro. Moreover, the accumulation of latent TGF-beta in the extracellular matrix significantly decreased in cultures exposed to an anti-maspin antibody and when cells were transfected with a maspin antisense-expressing vector. In contrast, accumulation of latent TGF-beta in the extracellular matrix increased after transfection of cells with a vector expressing maspin. CONCLUSIONS: These findings suggest that maspin expressed in active osteoblasts plays an important physiological role during maturation of the bone matrix, and in particular, during the process of accumulation of latent TGF-beta in the extracellular matrix.