Capability of Tissue Stem Cells to Organize into Salivary Rudiments

Branching morphogenesis (BrM), an essential step for salivary gland development, requires epithelial-mesenchymal interactions. BrM is impaired when the surrounding mesenchyme is detached from the salivary epithelium during the pseudoglandular stage. It is believed that the salivary mesenchyme is indispensable for BrM, however, an extracellular matrix gel with exogenous EGF can be used as a substitute for the mesenchyme during BrM in the developing salivary epithelium. Stem/progenitor cells isolated from salivary glands in humans and rodents can be classified as mesenchymal stem cell-like, bone-marrow-derived, duct cell-like, and embryonic epithelium-like cells. Salivary-gland-derived progenitor (SGP) cells isolated from duct-ligated rats, mice, and swine submandibular glands share similar characteristics, including intracellular laminin and α6β1-integrin expression, similar to the embryonic salivary epithelia during the pseudoglandular stage. Progenitor cells also isolated from human salivary glands (human SGP cells) having the same characteristics differentiate into hepatocyte-like cells when transplanted into the liver. Similar to the dissociated embryonic salivary epithelium, human SGP cells aggregate to self-organize into branching organ-like structures on Matrigel plus exogenous EGF. These results suggest the possibility that tissue stem cells organize rudiment-like structures, and the embryonic cells that organize into whole tissues during development are preserved even in adult tissues

Reconstitution of Mouse Spermatogonial Stem Cell Niches in Culture

SummarySpermatogonial stem cells (SSCs) reside in specific niches within seminiferous tubules. These niches are thought to secrete chemotactic factors for SSCs, because SSCs migrate to them upon transplantation. However, the identity of these chemotactic molecules remains unknown. Here, we established a testis feeder cell culture system and used it to identify SSC chemotactic factors. When seeded on testis cells from infertile mice, SSCs migrated beneath the Sertoli cells and formed colonies with a cobblestone appearance that were very similar to those produced by hematopoietic stem cells. Cultured cells maintained SSC activity and fertility for at least 5 months. Cobblestone colony formation depended on GDNF and CXCL12, and dominant-negative GDNF receptor transfection or CXCL12 receptor deficiency reduced SSC colonization. Moreover, GDNF upregulated CXCL12 receptor expression, and CXCL12 transfection in Sertoli cells increased homing efficiency. Overall, our findings identify GDNF and CXCL12 as SSC chemotactic factors in vitro and in vivo

Transcriptional repression and DNA hypermethylation of a small set of ES cell marker genes in male germline stem cells

BACKGROUND: We previously identified a set of genes called ECATs (ES cell-associated transcripts) that are expressed at high levels in mouse ES cells. Here, we examine the expression and DNA methylation of ECATs in somatic cells and germ cells. RESULTS: In all ECATs examined, the promoter region had low methylation levels in ES cells, but higher levels in somatic cells. In contrast, in spite of their lack of pluripotency, male germline stem (GS) cells expressed most ECATs and exhibited hypomethylation of ECAT promoter regions. We observed a similar hypomethylation of ECAT loci in adult testis and isolated sperm. Some ECATs were even less methylated in male germ cells than in ES cells. However, a few ECATs were not expressed in GS cells, and most of them targets of Oct3/4 and Sox2. The Octamer/Sox regulatory elements were hypermethylated in these genes. In addition, we found that GS cells express little Sox2 protein and low Oct3/4 protein despite abundant expression of their transcripts. CONCLUSION: Our results suggest that DNA hypermethylation and transcriptional repression of a small set of ECATs, together with post-transcriptional repression of Oct3/4 and Sox2, contribute to the loss of pluripotency in male germ cells

Thermal Probe Measurements of Energy Flux onto a Substrate in Inductively Coupled Plasmas

ナノダイナミクス国際シンポジウム 平成22年1月21日(木) 於長崎大学Nagasaki Symposium on Nano-Dynamics 2010 (NSND2010), January 21, 2010, Nagasaki University, Nagasaki, Japan, Invited Lectur

Dysphagia Screening Questionnaire : Swallow-10

The Seirei dysphagia screening questionnaire (namely, Seirei dsq) has been used to screen for oropharyngeal dysphagia (OD). Some of the questions in the questionnaire are difficult for people with cognitive decline to answer. We selected 10 items from the Seirei dsq that could be assessed by others, such as care workers (named Swallow-10). This study aims to verify the validity of the scoring method used in Swallow-10. The dataset used in this study was the one used in the development of Seirei dsq : 50 patients with cerebrovascular disease who were diagnosed with OD, 145 patients with cerebrovascular disease who did not have OD, and 170 healthy subjects. Among the answer choices, “A” for severe symptom, “B” for mild symptom and “C” for no symptom were scored with 4, 1 and 0 points respectively. Factor analysis extracted two factors : one related to pharyngeal function and another related to oral function. In addition, the Cronbach’s alpha coefficient was 0.84. ROC analysis indicated that optimal cutoff value was 5 points, with a sensitivity of 90.0% and a specificity of 88.5%. These results suggest that Swallow-10 may be useful as an OD screening tool for subjects with cognitive decline

Multicenter phase II trial of preoperative chemoradiotherapy with S-1 for locally advanced oral squamous cell carcinoma

PURPOSE: We evaluated whether preoperative chemotherapy with S-1 and concurrent radiotherapy is feasible and efficacious in the treatment of advanced oral squamous cell carcinoma. METHODS: Participants comprised 39 patients with oral carcinoma (stage III, n = 15; stage IVA, n = 24). All patients received a total radiation dose of 40 Gy, in once-daily 2-Gy fractions, and received S-1 at 65 mg/m(2)/day for 5 consecutive days, over 4 consecutive weeks with concurrent radiotherapy. RESULTS: Hematological toxicity was mild and reversible. The most common non-hematological toxicity was grade 3 mucositis, but this was transient and tolerable. Radical surgery was performed for 37 patients, with the remaining 2 patients declining the surgery. Postoperatively, local failure developed in 1 patient, and neck failure in 2 patients. Distant metastases were identified in 4 patients. At a median follow-up of 38.0 months (range 23–88 months), locoregional control, disease-specific survival, and overall survival rates at 3 years were 91.5, 83.8, and 83.8 %, respectively. CONCLUSION: Concurrent administration of S-1 and radiotherapy combined with surgery offers a well-tolerated method of successfully treating advanced oral squamous cell carcinoma. The locoregional control rate remains high even at 3 years of follow-up, and no serious adverse effects have been encountered

Deposition of transparent conducting Al-doped ZnO thin films by ICP-assisted sputtering

Aluminum-doped zinc oxide (AZO) is one of the promising transparent conductive oxide materials, which is expected to be an alternative to tin-doped indium oxide (ITO) that for long has been widely used in industry. The authors have been engaged in the development of AZO deposition process using inductively-coupled plasma assisted sputtering in a couple of years. This paper reports the results showing effectiveness of inductively coupled plasma (ICP) assisted sputtering in AZO film deposition process.2010 IEEE Region 10 Conference (TENCON 2010) : Fukuoka, 2010.11.21-2010.11.2

Phenotypic Plasticity of Mouse Spermatogonial Stem Cells

BACKGROUND:Spermatogonial stem cells (SSCs) continuously undergo self-renewal division to support spermatogenesis. SSCs are thought to have a fixed phenotype, and development of a germ cell transplantation technique facilitated their characterization and prospective isolation in a deterministic manner; however, our in vitro SSC culture experiments indicated heterogeneity of cultured cells and suggested that they might not follow deterministic fate commitment in vitro. METHODOLOGY AND PRINCIPAL FINDINGS:In this study, we report phenotypic plasticity of SSCs. Although c-kit tyrosine kinase receptor (Kit) is not expressed in SSCs in vivo, it was upregulated when SSCs were cultured on laminin in vitro. Both Kit(-) and Kit(+) cells in culture showed comparable levels of SSC activity after germ cell transplantation. Unlike differentiating spermatogonia that depend on Kit for survival and proliferation, Kit expressed on SSCs did not play any role in SSC self-renewal. Moreover, Kit expression on SSCs changed dynamically once proliferation began after germ cell transplantation in vivo. CONCLUSIONS/SIGNIFICANCE:These results indicate that SSCs can change their phenotype according to their microenvironment and stochastically express Kit. Our results also suggest that activated and non-activated SSCs show distinct phenotypes

Cell–matrix interaction via CD44 is independently regulated by different metalloproteinases activated in response to extracellular Ca2+ influx and PKC activation

CD44 is an adhesion molecule that interacts with hyaluronic acid (HA) and undergoes sequential proteolytic cleavages in its ectodomain and intramembranous domain. The ectodomain cleavage is triggered by extracellular Ca2+ influx or the activation of protein kinase C. Here we show that CD44-mediated cell–matrix adhesion is terminated by two independent ADAM family metalloproteinases, ADAM10 and ADAM17, differentially regulated in response to those stimuli. Ca2+ influx activates ADAM10 by regulating the association between calmodulin and ADAM10, leading to CD44 ectodomain cleavage. Depletion of ADAM10 strongly inhibits the Ca2+ influx-induced cell detachment from matrix. On the other hand, phorbol ester stimulation activates ADAM17 through the activation of PKC and small GTPase Rac, inducing proteolysis of CD44. Furthermore, depletion of ADAM10 or ADAM17 markedly suppressed CD44-dependent cancer cell migration on HA, but not on fibronectin. The spatio-temporal regulation of two independent signaling pathways for CD44 cleavage plays a crucial role in cell–matrix interaction and cell migration