Initial stages of development of the submandibular gland (human embryos at 5.5–8 weeks of development)

The aim of this study was to determine the main stages of submandibular salivary gland development during the embryonic period in humans. In addition, we studied submandibular salivary gland development in rats on embryonic days 14–16 and expression in the submandibular salivary gland region with the monoclonal antibody HNK‐1. Serial sections from 25 human embryos with a greatest length ranging from 10 to 31 mm (Carnegie stages 16–23; weeks 5.5–8 of development) and Wistar rats of embryonic days (E) 14–16 were analysed with light microscopy. Five stages of submandibular salivary gland development were identified. The prospective stage (1), between weeks 5.5 and early week 6, is characterized by a thickening of the epithelium of the medial paralingual groove in the floor of the mouth corresponding to the primordium of the submandibular salivary gland parenchyma. At this stage, the primordium of the parasympathetic ganglion lies below the lingual nerve. The primordium of the submandibular salivary gland parenchyma is observed in rats on E14 in the medial paralingual groove with mesenchymal cells, underlying the lingual nerve. These cells are HNK‐1‐positive, corresponding to the primordium of the parasympathetic ganglion. The bud stage (2), at the end of week 6 in humans and on E15 in rats, is characterized by the proliferation and invagination of the epithelial condensation, surrounded by an important condensation of the mesenchyme. The pseudoglandular stage (3) at week 6.5 is characterized by the beginning of the formation of lobes in the condensed mesenchyme. The canalicular stage (4), between week 7 and 7.5, is characterized by the appearance of a lumen in the proximal part of the submandibular duct. The innervation stage (5) occurs during week 8, with the innervation of the submandibular and interlobular ducts. Nervous branches arriving from the parasympathetic ganglion innervate the glandular parenchyma. Numerous blood vessels are observed nearby. Our results suggest that submandibular salivary gland development requires interactions among epithelium, mesenchyme, parasympathetic ganglion and blood vessels.     

Effect of using slush nitrogen (SN2) on development of microsurgically manipulated vitrified/warmed mouse embryos

BACKGROUND: This study evaluated the effect of vitrification using slush nitrogen (SN(2)) on cryopreservation of micromanipulated mouse embryos. METHODS: The zona pellucida of 4-cell embryos was either left intact or dissected or dissected with biopsy of an intact blastomere. In a second study, a blastomere was destroyed and either removed (removed group) or not removed (remained group) prior to vitrification/freezing. The micromanipulated embryos were equilibrated and loaded into an open pulled straw (OPS), and plunged into liquid nitrogen (LN(2)) or SN(2). RESULTS: When using LN(2) vitrification, recovery and blastocyst formation rates of embryos were lower for zona pellucida-opened and/or blastomere-biopsied embryos compared with zona pellucida-intact embryos. Using SN(2) for vitrification resulted in increased survival and development of vitrified/warmed embryos in both the zona pellucida-opened and blastomere-biopsy groups. Similar results were observed when using embryos with a destroyed blastomere either removed or left remaining before vitrification. However, the number of total and apoptotic cells were similar for both LN(2) and SN(2). In addition, using SN(2) increased the rate of intact recovery and blastocyst formation in warmed hemi-8-cell embryos derived from the same embryo. CONCLUSIONS: These results suggest that vitrification using SN(2) is useful in cryopreservation of micromanipulated embryos obtained from a variety of programs, including assisted hatching, preimplantation genetic diagnosis and nuclear transfer.     

沙利度胺对TGF-β_1诱导HELF细胞CTGF基因启动子结合蛋白变化的干预作用

目的:探讨沙利度胺(thalidomide,THD)和转化生长因子β_1(transformation growth factor-β_1,TGF-β_1)对人胚肺成纤维细胞(human embryonic lung fibroblasts,HELF)中结缔组织生长因子(connective tissue growth factor,CTGF)基因启动子的作用及其分子机制。方法:利用CTGF基因启动子驱动的萤光素酶报告基因系统观察TGF-β_1和THD对HELF细胞CTGF基因启动子活性的影响;同时以带有生物素标记的CTGF基因启动子序列作为探针,采用DNA pull-down技术分析TGF-β_1和THD对CTGF基因启动子结合蛋白的影响。结果:TGF-β_1能显著增强HELF细胞中报告基因的活性(P0.01),而THD以剂量依赖方式显著抑制TGF-β_1上调报告基因活性的效应(P0.01)。同时,TGF-β_1引起的CTGF基因启动子结合蛋白变化也能被THD所抑制(P0.05)。结论:CTGF基因启动子结合蛋白调节可能参与TGF-β_1对HELF细胞中CTGF基因启动子的激活过程,而THD能有效拮抗此过程。     

Novel approaches to study coronary vasculature development in mice

Background : Coronary artery development is an intensely studied field. Mice are a popular genetic model for developmental studies, but there is no widely accepted protocol for high‐throughput, high‐resolution imaging of their developmental and adult coronary artery anatomy. Results : Using tissue‐clearing protocols and confocal microscopy, we have analyzed embryonic and juvenile mouse hearts in Cx40:GFP knock‐in models with a special focus on septal artery development. We found that the septal artery, which supplies the interventricular septum, was initially formed as an arterial plexus that connected to both the left and right coronary arteries. During development, the plexus was remodeled into a single tube, which then remained connected only to the right coronary artery. Since optical imaging became limited at postnatal stages, it was supplemented with injection techniques using India ink and Microfil; the latter was subsequently analyzed with micro‐CT to visualize the anatomy of coronary vessels in 3D. Conclusions : The techniques described here enable us to study the finer details of coronary artery development in mice and can, therefore, be implemented to study the pathogenesis of coronary malformations in various mouse models. Developmental Dynamics 247:1018‐1027, 2018. © 2018 Wiley Periodicals, Inc.     

Attaining in vivo selectivity of positive modulation of α3βγ2 GABAA receptors in rats: A hard task!

It is unclear whether GABA_A receptors (GABA_ARs) that contain the α3-subunit are substantially involved in the anxiolytic effects of benzodiazepines (BDZs). In the present study, we tested YT-III-31, a newer BDZ ligand with functional preference for α3βγ2 GABA_ARs, in two paradigms of unconditioned anxiety, the open field and elevated plus maze in rats. The effective dose of YT-III-31 (2?mg/kg) displayed a clear anxiolytic-like profile, unhampered by sedative action, in both tests. At a higher dose (10?mg/kg), YT-III-31 induced ataxia in the rotarod and sedation in spontaneous locomotor activity test. The latter effect was preventable by flumazenil and βCCt, the non-selective and α1βγ2 GABA_AR affinity-selective antagonist, respectively, demonstrating that sedative properties of YT-III-31, when attained, are mediated by the α1γ2 site. To elucidate the receptor substrate of subtle behavioral differences between YT-III-31 and diazepam, we approximated in vivo receptor potentiation for both ligands, based on estimated unbound concentrations in rat brains. Far different from diazepam, YT-III-31 has significantly lower affinity for the α1γ2 over other BDZ-sensitive sites, and at lower doses (1–2?mg/kg) was devoid of potentiation at α1βγ2 GABA_ARs. The approximation approach revealed a modest selectivity of YT-III-31 for α3γ2- in comparison to α2γ2 and α5γ2 binding sites, suggesting that its anxiolytic-like activity may not necessarily or predominantly reflect potentiation at α3βγ2 GABA_ARs. Nonetheless, as the anxiolytic effects are achievable at a dose devoid of any sedative potential, and having favorable safety (cytotoxicity) and metabolic stability profile, YT-III-31 represents a valuable candidate for further translational research.     

Pancreatic islet differentiation of human embryonic stem cells by microRNA overexpression

Development of stem cell‐based therapies for the treatment of type 1 diabetes would provide a renewable supply of human β‐cells. Human embryonic stem cells (ESCs) are considered to be one of the stem cell populations with sufficient proliferative capacity to achieve this goal. Currently, differentiation protocols directing ESCs toward a pancreatic fate employ a variety of expensive cytokines and inhibitors. With the known significance of microRNAs in islet development, we present a novel and cost‐effective strategy in which miR‐375 overexpression promotes pancreatic endocrine differentiation in hESCs in the absence of any extrinsic factors. miR‐375 has been shown to be a key regulator of pancreatic development and function in zebrafish, mouse and human. In this study, hESCs were transduced with lentiviral vectors containing human miR‐375 precursor and aggregated to form human embryoid bodies (hEBs) for up to 21 days. Morphological assessment, immunocytochemistry and DTZ staining confirmed that miR‐375‐induced hEBs have similar characteristics to those of mature islets. In addition, the dynamic expression profile of endodermal marker Foxa2 and endocrine‐specific genes, including HNF4α, Pdx1, Pax6, Nkx6.1, Glut2 and insulin, were detected by quantitative real‐time PCR. Finally, insulin release upon glucose stimulation was detected in our differentiated clusters. The data presented here demonstrate the feasibility of using microRNAs to direct differentiation into the pancreatic lineage. Copyright © 2013 John Wiley & Sons, Ltd.     

Dynamic three‐dimensional micropatterned cell co‐cultures within photocurable and chemically degradable hydrogels

In this paper we report on the development of dynamically controlled three‐dimensional (3D) micropatterned cellular co‐cultures within photocurable and chemically degradable hydrogels. Specifically, we generated dynamic co‐cultures of micropatterned murine embryonic stem (mES) cells with human hepatocellular carcinoma (HepG2) cells within 3D hydrogels. HepG2 cells were used due to their ability to direct the differentiation of mES cells through secreted paracrine factors. To generate dynamic co‐cultures, mES cells were first encapsulated within micropatterned photocurable poly(ethylene glycol) (PEG) hydrogels. These micropatterned cell‐laden PEG hydrogels were subsequently surrounded by calcium alginate (Ca‐Alg) hydrogels containing HepG2 cells. After 4 days, the co‐culture step was halted by exposing the system to sodium citrate solution, which removed the alginate gels and the encapsulated HepG2 cells. The encapsulated mES cells were then maintained in the resulting cultures for 16 days and cardiac differentiation was analysed. We observed that the mES cells that were exposed to HepG2 cells in the co‐cultures generated cells with higher expression of cardiac genes and proteins, as well as increased spontaneous beating. Due to its ability to control the 3D microenvironment of cells in a spatially and temporally regulated manner, the method presented in this study is useful for a range of cell‐culture applications related to tissue engineering and regenerative medicine. Copyright © 2013 John Wiley & Sons, Ltd.     

Systematic review of plasma-membrane ecto-ATP synthase: A new player in health and disease

This review summarizes recent studies on plasma-membrane ecto-ATP synthase from structural and functional standpoints to possible pathophysiological roles. This review discusses significant new contributions and perspectives in the area of ecto-ATP synthase since the topic was last reviewed in 2015. Following an extensive summary of the cell types in which the ecto-ATP synthase is present, its structural and functional mechanism are discussed and physiological and pathological roles of the ecto-ATP synthase are reviewed and evaluated. Attempts to define the possible role of ecto-ATP synthase as possible target for anti-cancer and anti-obesity interventions are discussed.     

Somatostatin receptor type 2 contributes to the self-renewal of murine embryonic stem cells

Aim:

The roles of G-protein coupled receptors (GPCRs) in stem cell biology remain unclear. In this study, we aimed to identify GPCRs that might contribute to the self-renewal of mouse embryonic stem cells (mESCs).

Methods:

The expression levels of pluripotent genes and GPCR gene were detected in E14 mESCs using PCR array and RT-PCR. Immunofluorescent staining was used to examine the expression of pluripotent markers and the receptor translocation. Western blot analysis was used to detect phosphorylation of signal proteins. Knock-down of receptor was conducted to confirm its role in pluripotency maintenance.

Results:

In leukemia inhibitory factor (LIF)-free medium, mESCs lost the typical morphology of pluripotency, accompanied by markedly decreases in expression of somatostatin receptor type 2 (SSTR2), as well as the pluripotency biomarkers Oct4, Sox2, Rex1 and Nanog. Addition of the SSTR2 agonist octreotide or seglitide (0.1–30 μmol/L) in LIF-free medium dose-dependently promoted the self-renewal of mESCs, whereas the SSTR2 antagonist S4 (0.03–3 μmol/L) dose-dependently blocked octreotide-induced self-renewal. Knock-down of SSTR2 significantly decreased the self-renewal of mESCs even in the presence of LIF. Addition of LIF (1000 U/mL) or octreotide (1 μmol/L) in LIF-free medium significantly increased both phosphorylation and nuclear ocalization of STAT3.

Conclusion:

The activation of SSTR2 contributes to the self-renewal of mESCs via activation of the STAT3 pathway.