Gene-Dose-Dependent Reduction Fshr Expression Improves Spatial Memory Deficits in Alzheimer's Mice.

Alzheimer's disease (AD) is a major progressive neurodegenerative disorder of the aging population. High post-menopausal levels of the pituitary gonadotropin follicle-stimulating hormone (FSH) are strongly associated with the onset of AD, and we have shown recently that FSH directly activates the hippocampal Fshr to drive AD-like pathology and memory loss in mice. To establish a role for FSH in memory loss, we used female 3xTg;Fshr+/+, 3xTg;Fshr+/- and 3xTg;Fshr-/- mice that were either left unoperated or underwent sham surgery or ovariectomy at 8 weeks of age. Unoperated and sham-operated 3xTg;Fshr-/- mice were implanted with 17ß-estradiol pellets to normalize estradiol levels. Morris Water Maze and Novel Object Recognition behavioral tests were performed to study deficits in spatial and recognition memory, respectively, and to examine the effects of Fshr depletion. 3xTg;Fshr+/+ mice displayed impaired spatial memory at 5 months of age; both the acquisition and retrieval of the memory were ameliorated in 3xTg;Fshr-/- mice and, to a lesser extent, in 3xTg;Fshr+/- mice- -thus documenting a clear gene-dose-dependent prevention of hippocampal-dependent spatial memory impairment. At 5 and 10 months, sham-operated 3xTg;Fshr-/- mice showed better memory performance during the acquasition and/or retrieval phases, suggesting that Fshr deletion prevented the progression of spatial memory deficits with age. However, this prevention was not seen when mice were ovariectomized, except in the 10-month-old 3xTg;Fshr-/- mice. In the Novel Object Recognition test performed at 10 months, all groups of mice, except ovariectomized 3xTg;Fshr-/- mice showed a loss of recognition memory. Consistent with the neurobehavioral data, there was a gene-dose-dependent reduction mainly in the amyloid ß40 isoform in whole brain extracts. Finally, serum FSH levels < 8 ng/mL in 16-month-old APP/PS1 mice were associated with better retrieval of spatial memory. Collectively, the data provide compelling genetic evidence for a protective effect of inhibiting FSH signaling on the progression of spatial and recognition memory deficits in mice, and lay a firm foundation for the use of an FSH-blocking agent for the early prevention of cognitive decline in postmenopausal women.

Pericytes modulate islet immune cells and insulin secretion through Interleukin-33 production in mice.

Introduction: Immune cells were recently shown to support ß-cells and insulin secretion. However, little is known about how islet immune cells are regulated to maintain glucose homeostasis. Administration of various cytokines, including Interleukin-33 (IL-33), was shown to influence ß-cell function. However, the role of endogenous, locally produced IL-33 in pancreatic function remains unknown. Here, we show that IL-33, produced by pancreatic pericytes, is required for glucose homeostasis. Methods: To characterize pancreatic IL-33 production, we employed gene expression, flow cytometry, and immunofluorescence analyses. To define the role of this cytokine, we employed transgenic mouse systems to delete the Il33 gene selectively in pancreatic pericytes, in combination with the administration of recombinant IL-33. Glucose response was measured in vivo and in vitro, and morphometric and molecular analyses were used to measure ß-cell mass and gene expression. Immune cells were analyzed by flow cytometry. Resuts: Our results show that pericytes are the primary source of IL-33 in the pancreas. Mice lacking pericytic IL-33 were glucose intolerant due to impaired insulin secretion. Selective loss of pericytic IL-33 was further associated with reduced T and dendritic cell numbers in the islets and lower retinoic acid production by islet macrophages. Discussion: Our study demonstrates the importance of local, pericytic IL-33 production for glucose regulation. Additionally, it proposes that pericytes regulate islet immune cells to support ß-cell function in an IL-33-dependent manner. Our study reveals an intricate cellular network within the islet niche.

The postnatal pancreatic microenvironment guides ß cell maturation through BMP4 production.

Glucose homeostasis depends on regulated insulin secretion from pancreatic ß cells, which acquire their mature phenotype postnatally. The functional maturation of ß cells is regulated by a combination of cell-autonomous and exogenous factors; the identity of the latter is mostly unknown. Here, we identify BMP4 as a critical component through which the pancreatic microenvironment regulates ß cell function. By combining transgenic mouse models and human iPSCs, we show that BMP4 promotes the expression of core ß cell genes and is required for proper insulin production and secretion. We identified pericytes as the primary pancreatic source of BMP4, which start producing this ligand midway through the postnatal period, at the age ß cells mature. Overall, our findings show that the islet niche directly promotes ß cell functional maturation through the timely production of BMP4. Our study highlights the need to recapitulate the physiological postnatal islet niche for generating fully functional stem-cell-derived ß cells for cell replacement therapy for diabetes.

The Role of Vascular Cells in Pancreatic Beta-Cell Function.

Insulin-producing ß-cells constitute the majority of the cells in the pancreatic islets. Dysfunction of these cells is a key factor in the loss of glucose regulation that characterizes type 2 diabetes. The regulation of many of the functions of ß-cells relies on their close interaction with the intra-islet microvasculature, comprised of endothelial cells and pericytes. In addition to providing islet blood supply, cells of the islet vasculature directly regulate ß-cell activity through the secretion of growth factors and other molecules. These factors come from capillary mural pericytes and endothelial cells, and have been shown to promote insulin gene expression, insulin secretion, and ß-cell proliferation. This review focuses on the intimate crosstalk of the vascular cells and ß-cells and its role in glucose homeostasis and diabetes.

NUPR1 acts as a pro-survival factor in human bone marrow-derived mesenchymal stem cells and is induced by the hypoxia mimetic reagent deferoxamine.

Differences in the culturing conditions of mesenchymal stem cells used in regenerative medicine may affect their differentiation ability, genome instability, and therapeutic effects. In particular, bone marrow-derived mesenchymal stem cells cultured under hypoxia are known to proliferate while maintaining an undifferentiated state and the use of deferoxamine, a hypoxia mimetic reagent, has proven to be a suitable strategy to maintain the cells under hypoxic metabolic state. Here, the deferoxamine effects were investigated in mesenchymal stem cells to gain insights into the mechanisms regulating stem cell survival. A 12-h deferoxamine treatment reduced proliferation, oxygen consumption, mitochondrial activity, and ATP production. Microarray analysis revealed that deferoxamine enhanced the transcription of genes involved in glycolysis and the HIF1α pathway. Among the earliest changes, transcriptional variations were observed in HIF1α, NUPR1, and EGLN, in line with previous reports showing that short deferoxamine treatments induce substantial changes in mesenchymal stem cells glycolysis pathway. NUPR1, which is induced by stress and involved in autophagy-mediated survival, was upregulated by deferoxamine in a concentration-dependent manner. Consistently, NUPR1 knockdown was found to reduce cell proliferation and increase the proapoptotic effect of staurosporine, suggesting that deferoxamine-induced NUPR1 promotes mesenchymal stem cell survival and cytoprotective autophagy. Our findings may substantially contribute to improve the effectiveness of mesenchymal stem cell-based regenerative medicine.

Enhanced survival of mice infused with bone marrow-derived as compared with adipose-derived mesenchymal stem cells.

AIM: Less invasive therapies using mesenchymal stem cells (MSC) are being developed to treat patients with severe liver cirrhosis. MSC constitute a promising cell source for regenerative therapy and are frequently isolated from bone marrow (BMSC) or adipose tissue (ASC). Therefore, this study assessed the characteristics of these two cell types and their safety for cell infusion. METHODS: In vitro, exhaustive genetic analysis was performed using human (h)BMSC and hASC. Subsequently, the expression of mRNA and protein was evaluated. In vivo, mouse (m)BMSC or mASC was infused into serial mice via the peripheral vein, and 24-h survival rate, prothrombin time and cause of death were analyzed. RESULTS: On polymerase chain reaction, western blotting, enzyme-linked immunoassay and fluorescence-activated cell sorting, tissue factor was found to be expressed at higher levels in hASC than in hBMSC. Prothrombin time in mice infused with mASC (>120 s) was markedly longer than that of untreated mice (6.5 ± 1.7 s) and that of mice infused with BMSC (6.7 ± 0.8 s) (P < 0.001), indicating that pro-coagulation activity was potently enhanced after ASC infusion. The 24-h survival rates in the mASC- and mBMSC-infused groups were 46.4% (13/28) and 95.5% (21/22), respectively; in the former, the rate decreased with increasing number of infused mASC. This cell number-dependent effect was not observed with mBMSC. A histopathological analysis of mice that died immediately following mASC infusion revealed multiple thrombi in the blood vessels of the lungs. CONCLUSION: These results indicate that BMSC are a superior and safer cell source for regenerative therapy.

Status and prospects of liver cirrhosis treatment by using bone marrow-derived cells and mesenchymal cells.

In 2003, we started autologous bone marrow cell infusion (ABMi) therapy for treating liver cirrhosis. ABMi therapy uses 400 mL of autologous bone marrow obtained under general anesthesia and infused mononuclear cells from the peripheral vein. The clinical study expanded and we treated liver cirrhosis induced by HCV and HBV infection and alcohol consumption. We found that the ABMi therapy was effective for cirrhosis patients and now we are treating patients with combined HIV and HCV infection and with metabolic syndrome-induced liver cirrhosis. Currently, to substantiate our findings that liver cirrhosis can be successfully treated by the ABMi therapy, we are conducting randomized multicenter clinical studies designated "Advanced medical technology B" for HCV-related liver cirrhosis in Japan. On the basis of our clinical study, we developed a proof-of-concept showing that infusion of bone marrow cells (BMCs) improved liver fibrosis and sequentially activated proliferation of hepatic progenitor cells and hepatocytes, further promoting restoration of liver functions. To treat patients with severe forms of liver cirrhosis, we continued translational research to develop less invasive therapies by using mesenchymal stem cells derived from bone marrow. We obtained a small quantity of BMCs under local anesthesia and expanded them into mesenchymal stem cells that will then be used for treating cirrhosis. In this review, we present our strategy to apply the results of our laboratory research to clinical studies.