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Extracellular vesicles (EVs) are known to be secreted by various cells. In particular, mesenchymal stem cell (MSC)-derived EVs (MSC-EVs) have tissue repair capacity and anti-inflammatory properties. Dental pulp stem cells (DPSCs), which are MSCs isolated from pulp tissue, are less invasive to the body than other MSCs and can be collected from young individuals. In this study, we investigated the efficacy of EVs secreted by DPSCs (DPSC-EVs) for bone formation. DPSC-EVs were isolated from the cell culture medium of DPSCs. DPSC-EVs were unilaterally injected along with collagen (COL), beta-tricalcium phosphate (β-TCP) or hydroxyapatite (HA) into rat calvarial bone defects. The effects of DPSC-EVs were analyzed by micro-computed tomography (micro-CT) and histological observation. Micro-CT showed that administration of DPSC-EVs with the abovementioned scaffolds resulted in bone formation in the periphery of the defects. DPSC-EVs/COL specifically resulted in bone formation in the center of the defects. Histological observation revealed that DPSC-EVs/COL promoted new bone formation. Administration of DPSC-EVs/COL had almost the same effect on the bone defect site as transplantation of DPSCs/COL. These results suggest that DPSC-EVs may be effective tools for bone tissue regeneration.

Aims/Introduction Dental pulp stem cells (DPSCs) are thought to be an attractive candidate for cell therapy. We recently reported that the transplantation of DPSCs increased nerve conduction velocity and nerve blood flow in diabetic rats. In the present study, we investigated the immunomodulatory effects of DPSC transplantation on diabetic peripheral nerves. Materials and Methods DPSCs were isolated from the dental pulp of Sprague–Dawley rats and expanded in culture. Eight weeks after the streptozotocin injection, DPSCs were transplanted into the unilateral hindlimb skeletal muscles. Four weeks after DPSC transplantation, neurophysiological measurements, inflammatory gene expressions and the number of CD68‐positive cells in sciatic nerves were assessed. To confirm the immunomodulatory effects of DPSCs, the effects of DPSC‐conditioned media on lipopolysaccharide‐stimulated murine macrophage RAW264.7 cells were investigated. Results Diabetic rats showed significant delays in sciatic nerve conduction velocities and decreased sciatic nerve blood flow, all of which were ameliorated by DPSC transplantation. The number of CD68‐positive monocytes/macrophages and the gene expressions of M1 macrophage‐expressed cytokines, tumor necrosis factor‐α and interleukin‐1β, were increased in the sciatic nerves of the diabetic rats. DPSC transplantation significantly decreased monocytes/macrophages and tumor necrosis factor‐α messenger ribonucleic acid expression, and increased the gene expression of the M2 macrophage marker, CD206, in the sciatic nerves of the diabetic rats. The in vitro study showed that DPSC‐conditioned media significantly increased the gene expressions of interleukin‐10 and CD206 in lipopolysaccharide‐stimulated RAW264.7 cells. Conclusions These results suggest that DPSC transplantation promoted macrophages polarization towards anti‐inflammatory M2 phenotypes, which might be one of the therapeutic mechanisms for diabetic polyneuropathy. Effects of DPSC transplantation on the inflammatory mRNA expressions in sciatic nerves. Transplantation of DPSCs significantly decreased TNF‐α gene expression and increased the CD206 gene expression in the sciatic nerves compared with the vehicle‐injected side in diabetic rats.

Aims/Introduction Dental pulp stem cells (DPSCs) can be easily obtained from teeth for general orthodontic reasons. We have previously reported the therapeutic effects of DPSC transplantation for diabetic polyneuropathy. As abundant secretomes from DPSCs are considered to play a central role in the improvement of diabetic polyneuropathy, we investigated whether direct injection of DPSC‐conditioned media (DPSC‐CM) into hindlimb skeletal muscles ameliorates diabetic polyneuropathy in diabetic rats. Materials and Methods DPSCs were isolated from the dental pulp of Sprague–Dawley rats. Eight weeks after the induction of diabetes, DPSC‐CM was injected into the unilateral hindlimb skeletal muscles in both normal and diabetic rats. The effects of DPSC‐CM on diabetic polyneuropathy were assessed 4 weeks after DPSC‐CM injection. To confirm the angiogenic effect of DPSC‐CM, the effect of DPSC‐CM on cultured human umbilical vascular endothelial cell proliferation was investigated. Results The administration of DPSC‐CM into the hindlimb skeletal muscles significantly ameliorated sciatic motor/sensory nerve conduction velocity, sciatic nerve blood flow and intraepidermal nerve fiber density in the footpads of diabetic rats. We also showed that DPSC‐CM injection significantly increased the capillary density of the skeletal muscles, and suppressed pro‐inflammatory reactions in the sciatic nerves of diabetic rats. Furthermore, an in vitro study showed that DPSC‐CM significantly increased the proliferation of umbilical vascular endothelial cells. Conclusions We showed that DPSC‐CM injection into hindlimb skeletal muscles has a therapeutic effect on diabetic polyneuropathy through neuroprotective, angiogenic and anti‐inflammatory actions. DPSC‐CM could be a novel cell‐free regenerative medicine treatment for diabetic polyneuropathy. We showed the therapeutic efficacy of dental pulp stem cell‐conditioned media (DPSC‐CM) injection into hindlimb skeletal muscles for diabetic polyneuropathy by neuroprotective, angiogenic and anti‐inflammatory actions. As the use of DPSC‐CM will lead to a reduction of the medical costs, maintenance of DPSC‐CM quality by using selected DPSCs with high viability, and freedom from immune incompatibility and tumorigenicity, DPSC‐CM injection could be a novel therapy for diabetic polyneuropathy.

Interleukin 18 (IL18) was originally identified as an inflammation-induced cytokine that is secreted by immune cells. An increasing number of studies have focused on its non-immunological functions, with demonstrated functions for IL18 in energy homeostasis and neural stability. IL18 is reportedly required for lipid metabolism in the liver and brown adipose tissue. Furthermore, IL18 (Il18) deficiency in mice leads to mitochondrial dysfunction in hippocampal cells, resulting in depressive-like symptoms and cognitive impairment. Microarray analyses of Il18−/− mice have revealed a set of genes with differential expression in liver, brown adipose tissue, and brain; however, the impact of IL18 deficiency in these tissues remains uncertain. In this review article, we discuss these genes, with a focus on their relationships with the phenotypic disease traits of Il18−/− mice.

The tight junction protein claudin-3 has been identified as a transcriptional target of the Wnt/β-catenin signaling pathway regulating blood-brain barrier (BBB) maturation. In neurological disorders loss of claudin-3 immunostaining is observed at the compromised BBB and blood-cerebrospinal fluid barrier (BCSFB). Although these observations support a central role of claudin-3 in regulating brain barriers’ tight junction integrity, expression of claudin-3 at the brain barriers has remained a matter of debate. This prompted us to establish claudin-3 −/− C57BL/6J mice to study the role of claudin-3 in brain barrier integrity in health and neuroinflammation. Bulk and single cell RNA sequencing and direct comparative qRT-PCR analysis of brain microvascular samples from WT and claudin-3 −/− mice show beyond doubt that brain endothelial cells do not express claudin-3 mRNA. Detection of claudin-3 protein at the BBB in vivo and in vitro is rather due to junctional reactivity of anti-claudin-3 antibodies to an unknown antigen still detected in claudin-3 −/− brain endothelium. We confirm expression and junctional localization of claudin-3 at the BCSFB of the choroid plexus. Our study clarifies that claudin-3 is not expressed at the BBB and shows that absence of claudin-3 does not impair brain barrier function during health and neuroinflammation in C57BL/6J mice.

A narrow and calcified sinotubular junction (STJ) represents a risk for ascending aortic dissection after balloon-expandable transcatheter aortic valve implantation (TAVI). The aim of this study was to assess computed tomography (CT)-based aortic root morphology in patients with aortic stenosis (AS), and to evaluate the feasibility of a two-step inflation technique that we devised for TAVI using the SAPIEN 3 in patients with a narrow and calcified STJ. We retrospectively analyzed the STJ diameter (STJD) as well the as aortic annulus diameter (AAD) and STJ calcification using CT imaging in 412 patients undergoing TAVI. We defined a “narrow STJ” as a minimum STJD that was smaller than the diameter corresponding to a 10% oversized annulus area, and a “calcified STJ” as an STJ calcification angle > 90°. A “narrow and calcified STJ” was identified in 54 patients (13.1%) of patients. Among them, we performed TAVI using the two-step inflation technique with SAPIEN 3 in 20 patients and compared with 11 patients that underwent the conventional inflation procedure. Two-step inflation was successfully performed without ascending aortic dissection in all 20 patients. The effective orifice area index at discharge in these 20 patients was similar to that in 11 patients who underwent the conventional inflation procedure for a “narrow and calcified STJ” [1.40 (1.20–1.51) vs. 1.33 (1.18–1.41) cm 2 /m 2 , p  = 0.23]. Although further assessment is required, the two-step inflation technique with the SAPIEN 3 is feasible for a narrow and calcified STJ.

Claudin-2 is highly expressed in tight junctions of mouse renal proximal tubules, which possess a leaky epithelium whose unique permeability properties underlie their high rate of NaCl reabsorption. To investigate the role of claudin-2 in paracellular NaCl transport in this nephron segment, we generated knockout mice lacking claudin-2 (Cldn2⁻/⁻). The Cldn2⁻/⁻ mice displayed normal appearance, activity, growth, and behavior. Light microscopy revealed no gross histological abnormalities in the Cldn2⁻/⁻ kidney. Ultrathin section and freeze-fracture replica electron microscopy revealed that, similar to those of wild types, the proximal tubules of Cldn2⁻/⁻ mice were characterized by poorly developed tight junctions with one or two continuous tight junction strands. In contrast, studies in isolated, perfused S2 segments of proximal tubules showed that net transepithelial reabsorption of Na⁺, Cl⁻, and water was significantly decreased in Cldn2⁻/⁻ mice and that there was an increase in paracellular shunt resistance without affecting the apical or basolateral membrane resistances. Moreover, deletion of claudin-2 caused a loss of cation (Na⁺) selectivity and therefore relative anion (Cl⁻) selectivity in the proximal tubule paracellular pathway. With free access to water and food, fractional Na⁺ and Cl⁻ excretions in Cldn2⁻/⁻ mice were similar to those in wild types, but both were greater in Cldn2⁻/⁻ mice after i.v. administration of 2% NaCl. We conclude that claudin-2 constitutes leaky and cation (Na⁺)-selective paracellular channels within tight junctions of mouse proximal tubules.

Lottocracy and epistocracy have received deeply insightful attention as political regimes. Herein, by conducting an experiment using an online survey, we explored the extent to which public opinion is receptive to political decisions under various regimes regarding two environmental policies: education policy and environmental tax policy. By doing so, we examined whether the presence of tax burdens affected the acceptability of political regimes, i.e., electoral democracy, lottocracy, and epistocracy. Our results revealed that decisions based on lottocracy and epistocracy were significantly less acceptable than those based on electoral democracy. Nevertheless, lottocratic and epistocratic decisions were more acceptable regarding the issue of environmental tax policy. The difference was mainly attributed to people's rejection of environmental tax policy offsetting their rejection of lottocracy and epistocracy. This suggests, first, that decisions based on electoral democracy increase policies' acceptability if they do not involve taxation, and second, that the status of whether or not a decision is electoral does not significantly affect policy acceptability if taxation is involved, whereas on the other hand, people are sensitive to differences between the regimes if the policy does not involve taxation.

The aim of this study was to assess the efficacy of a self-assembling peptide hydrogel as a scaffold for bone regeneration. We used a neutral and injectable self-assembling peptide hydrogel, SPG-178-Gel. Bone defects (5 mm in diameter) in rat calvarial bones were filled with a mixture of alpha-modified Eagle's medium and peptide hydrogel. Three weeks after surgery, soft X-ray and microcomputed tomography (micro-CT) images of the gel-treated bones showed new bone formations in the periphery and in central areas of the defects. Next, we evaluated the three-dimensional osteogenic induction of dental pulp stem cells (DPSCs), a type of mesenchymal stem cell, in SPG-178-Gel. We first confirmed that the osteogenic differentiation of DPSCs was significantly promoted by osteogenic induction medium containing recombinant human bone morphogenetic protein-4 (rhBMP-4) in a two-dimensional cell culture. Then, we verified DPSC proliferation and osteogenic differentiation in a three-dimensional cell culture using SPG-178-Gel. The gene expression levels of osteopontin, osteocalcin, and collagen type I were significantly increased when DPSCs were cultured in SPG-178-Gel with the osteogenic induction medium. Micro-CT observations showed the formation of widespread calcium deposition. In conclusion, SPG-178-Gel was adequately effective as a scaffold and can be a suitable tool for bone formation in vivo and in vitro. These findings suggest that the self-assembling peptide hydrogel, SPG-178-Gel, could be a promising tool for bone tissue engineering.

Interleukin-18 (IL18) is an inflammatory cytokine that is related to psychiatric disorders such as depression and cognitive impairment. We previously found that IL18 deficiency may cause hippocampal impairment, resulting in depression-like behavioral changes. However, the potential role of IL18 in stressful conditions remains uncertain. In the present study, we examined the effect of IL18 on neural inflammation and stress tolerance during acute stress. Littermate Il18 +/+ and Il18 −/− mice were exposed to a single restraint stress for 6 h, and all assessments were performed 18 h after the mice were released from the restraint. In Il18 −/− mice exposed to acute stress, the immobility times in both the forced swim test and tail suspension test were decreased, although no difference was observed in Il18 +/+ mice. Il1β , Il6 , and Tnfα expression levels in the hippocampus of stressed Il18 −/− mice were significantly higher than those in the other groups. Moreover, the numbers of astrocytes and microglia, including those in the active form, were also increased compared with those in other groups. Regarding the molecular mechanism, the HSF5 and TTR genes were specifically expressed in stressed Il18 −/− mice. As a potential treatment, intracerebral administration of IL18 to Il18 −/− mice resulted in partial recovery of changes in behavioral assessments. Our results revealed that IL18-deficient mice were more sensitive and had a longer response to acute stress than that in normal mice. In addition, neural inflammation and augmentation of glucocorticoid signals caused by stress were more intense and remained longer in Il18 −/− mice, resulting in behavioral changes. In conclusion, IL18 might be an indispensable factor that modulates the stress response and maintains balance between neural inflammation and glucocorticoid signaling.