Effect of Metformin on Glucagon-Like Peptide 1 (GLP-1) and Leptin Levels in Obese Nondiabetic Subjects

OBJECTIVE—To evaluate the effects of metformin on glucagon-like peptide 1 (GLP-1) and leptin levels. RESEARCH DESIGN AND METHODS—A total of 10 obese nondiabetic male patients were studied before and after a 14-day treatment with 2,550 mg/day metformin and were compared with 10 untreated obese control subjects. On days 0 and 15, leptin and GLP-1(7–36)amide/(7–37) levels were assessed before and after an oral glucose load during a euglycemic hyperinsulinemic clamp to avoid the interference of variations of insulinemia and glycemia on GLP-1 and leptin secretion. The effects of metformin on GLP-1(7–36)amide degradation in human plasma and in a buffer solution containing dipeptidyl peptidase IV (DPP-IV) were also studied. RESULTS—Leptin levels were not affected by the oral glucose load, and they were not modified after metformin treatment. Metformin induced a significant (P < 0.05) increase of GLP-1(7–36)amide/(7–37) at 30 and 60 min after the oral glucose load (63.8 ± 29.0 vs. 50.3 ± 15.6 pmol/l and 75.8 ± 35.4 vs. 46.9 ± 20.0 pmol/l, respectively), without affecting baseline GLP-1 levels. No variations of GLP-1 levels were observed in the control group. In pooled human plasma, metformin (0.1–0.5 μg/ml) significantly inhibited degradation of GLP-1(7–36)amide after a 30-min incubation at 37°C; similar results were obtained in a buffer solution containing DPP-IV. CONCLUSIONS—Metformin significantly increases GLP-1 levels after an oral glucose load in obese nondiabetic subjects; this effect could be due to an inhibition of GLP-1 degradation

Simple and Rapid Non-Enzymatic Procedure Allows the Isolation of Structurally Preserved Connective Tissue Micro-Fragments Enriched with SVF

The stromal vascular fraction (SVF) consists of a heterogeneous population of stem and stromal cells, generally obtained from adipose tissue by enzymatic digestion. For human cell-based therapies, mechanical process methods to obtain SVF represent an advantageous approach because they have fewer regulatory restrictions for their clinical use. The aim of this study was to characterize a novel commercial system for obtaining SVF from adipose tissue by a mechanical approach without substantial manipulations. Lipoaspirate samples collected from 27 informed patients were processed by a simple and fast mechanical system (by means of Hy-Tissue SVF). The Hy-Tissue SVF product contained a free cell fraction and micro-fragments of stromal connective tissue. The enzymatic digestion of the micro-fragments increased the yield of free cells (3.2 times) and CFU-F (2.4 times). Additionally, 10% of free cells from SVF were positive for CD34+, suggesting the presence of endothelial cells, pericytes, and potential adipose-derived stem cells (ADSC). Moreover, the SVF cells were able to proliferate and differentiate in vitro toward adipocytes, osteocytes, and chondrocytes. The immunophenotypic analysis of expanded cells showed positivity for typical mesenchymal stem cell markers. The Hy-Tissue SVF system allows the isolation of stromal vascular fraction, making this product of potential interest in regenerative medicine

Adipokines as Possible New Predictors of Cardiovascular Diseases: A Case Control Study

Background and Aims. The secretion of several adipocytokines, such as adiponectin, retinol-binding protein 4 (RBP4), adipocyte fatty acid binding protein (aFABP), and visfatin, is altered in subjects with abdominal adiposity; these endocrine alterations could contribute to increased cardiovascular risk. The aim of the study was to assess the relationship among adiponectin, RBP4, aFABP, and visfatin, and incident cardiovascular disease. Methods and Results. A case-control study, nested within a prospective cohort, on 2945 subjects enrolled for a diabetes screening program was performed. We studied 18 patients with incident fatal or nonfatal IHD (Ischemic Heart Disease) or CVD (Cerebrovascular Disease), compared with 18 matched control subjects. Circulating adiponectin levels were significantly lower in cases of IHD with respect to controls. Circulating RBP4 levels were significantly increased in CVD and decreased in IHD with respect to controls. Circulating aFABP4 levels were significantly increased in CVD, while no difference was associated with IHD. Circulating visfatin levels were significantly lower in cases of both CVD and IHD with respect to controls, while no difference was associated with CVD. Conclusions. The present study confirms that low adiponectin is associated with increased incidents of IHD, but not CVD, and suggests, for the first time, a major effect of visfatin, aFABP, and RBP4 in the development of cardiovascular disease

A Correlative Imaging Study of in vivo and ex vivo Biodistribution of Solid Lipid Nanoparticles

Purpose: Solid lipid nanoparticles are largely used in biomedical research and are characterized by high stability and biocompatibility and are also able to improve the stability of various loaded molecules. In vitro studies demonstrated that these nanoparticles are low cytotoxic, while in vivo studies proved their efficiency as nanocarriers for molecules characterized by a low bioavailability. However, to our knowledge, no data on the systemic biodistribution and organ accumulation of solid lipid nanoparticles in itself are presently available. Methods: In this view, we investigated the solid lipid nanoparticles biodistribution by a multimodal imaging approach correlating in vivo and ex vivo analyses. We loaded solid lipid nanoparticles with two different fluorophores (cardiogreen and rhodamine) to observe them with an optical imager in the whole organism and in the excised organs, and with fluorescence microscopy in tissue sections. Light and transmission electron microscopy analyses were also performed to evaluate possible structural modification or damage due to nanoparticle administration. Results: Solid lipid nanoparticles loaded with the two fluorochromes showed good optic characteristics and stable polydispersity. After in vivo administration, they were clearly detectable in the organism. Four hours after the injection, the fluorescent signal occurred in anatomical districts corresponding to the liver and this was confirmed by the ex vivo acquisitions of excised organs. Brightfield, fluorescence and transmission electron microscopy confirmed solid lipid nanoparticles accumulation in hepatocytes without structural damage. Conclusion: Our results support the systemic biocompatibility of solid lipid nanoparticles and demonstrate their detailed biodistribution from the whole organism to organs until the cells

In vitro characterization of adipose stem cells non-enzymatically extracted from the thigh and abdomen

Autologous fat grafting is a surgical technique in which adipose tissue is transferred from one area of the body to another, in order to reconstruct or regenerate damaged or injured tissues. Before reinjection, adipose tissue needs to be purified from blood and cellular debris to avoid inflammation and preserve the graft viability. To perform this purification, different enzymatic and mechanical methods can be used. In this study, we characterized in vitro the product of a closed automatic device based on mechanical disaggregation, named Rigenera\uae, focusing on two sites of adipose tissue harvesting. At first, we optimized the Rigenera\uae operating timing, demonstrating that 60 s of treatment allows a higher cellular yield, in terms of the cell number and growth rate. This result optimizes the mechanical disaggregation and it can increase the clinical efficiency of the final product. When comparing the extracted adipose samples from the thigh and abdomen, our results showed that the thigh provides a higher number of mesenchymal-like cells, with a faster replication rate and a higher ability to form colonies. We can conclude that by collecting adipose tissue from the thigh and treating it with the Rigenera\uae device for 60 s, it is possible to obtain the most efficient product

In vivo and in vitro biodistribution of solid lipid nanoparticles

Solid lipid nanoparticles (SLN) are a versatile tool with a high potential of applications. They are constituted by biocompatible and biodegradable matrix with well-established safety profiles. Their matrix can improve the stability and bioavailability of labile molecules, assuring restrained release profile. Moreover, due to the physicochemical properties of lipids (i.e. the low melting temperature), SLN can be easily obtained by direct emulsification of the molten lipids and subsequent recrystallization, thus avoiding the use of potentially toxic solvents that are commonly required for the preparation of polymeric nanoparticles (1). SLN used for this study were produced by a protocol based on emulsification of the molten lipids in water by melt and ultra-sonication method (2), and were functionalized with polysorbate 80 (SLN-P80) for in vivo administration. In fact, it has been reported that this surfactant extend the nanoparticle circulation time in the blood, avoiding opsonization with the complement activation and uptake by the reticulo-endothelial system. The influence of nanoparticle composition and functionalization was investigated on morphology, dimension and inner structure by mean of cryogenic transmission electron microscopy (cryo-TEM), X-ray diffraction measurements, photon correlation spectroscopy (PCS) and sedimentation field flow fractionation (SdFFF) (2). SLN-P80 were labeled with cardiogreen fluorophore to allow their visualization in living organisms, and the in vivo biodistribution was evaluated with Fluorescent Luminescent Imaging (FLI) after intraperitoneal (i.p.) administration in a mice model. After the in vivo acquisition, mice were perfused and the excised organs (liver, kidney, spleen, brain, lung) were acquired to confirm SLN-P80 accumulation in specific districts (3). Organ tissues were also analyzed at light microscopy (LM) to evaluate SLN-P80 localization. After 4 h from systemic administration, SLN-P80 specifically accumulated in liver (Fig. 1a). LM revealed that no histological alteration is induced by SLN-P80 administration; however, a marked increase in lipid content (red oil staining) was found in hepatocytes, especially close to the centrilobular venula (Fig. 1b,c). To clarify this phenomenon, we investigated in vitro the uptake and intracellular fate of SLN-P80 in a murine cell line. 3T3 cells were incubated with SLN-P80 for 1, 4 and 24h, and then processed for both LM (red oil staining) and transmission electron microscopy (TEM). SLN-P80 administration induced accumulation of lipid droplets already after 1 h (Fig. 2a,b). At TEM scarce SLN-P80 were observed inside the cells: they occurred free in the cytoplasm, often in close proximity to lipid droplets showing a peripheral electron dense material (Fig. 2c). This suggests that SLN-P80 enter the cells by fusion with the plasma membrane, undergo rapid degradation and their components migrate, probably due to chemical affinity, into the lipid deposits

Validation of the Italian version of the questionnaire on nutrition knowledge by Moynihan

Background and aims. A series of validation studies was performed on the Moynihan questionnaire to obtain data on nutrition knowledge, translated and adapted to Italian eating habits. Higher scores mean lower knowledge. Methods. Test-retest reliability was assessed administering the questionnaire at a 15-day interval in 52 inpatients. Factor structure and correlation with demographic and anthropometric characteristics were studied on a larger sample, which included a number of health professionals. Finally, sensitivity to change induced by an educational program was verified in a sample of 11 patients with type 1 diabetes. Results. Test-retest reliability was satisfactory; factor structure suggested one single principal component. Test scores were inversely correlated with age (r=0.24; p=0.02), but not with body mass index or waist circumference. Patients with higher education show a greater degree of nutrition knowledge. Among type 1 diabetic patients, an educational program induces a significant improvement of test scores (from 20.6 [18.6-22.8] to 16.6 [15.5-17.7], p=0.003). Conclusions. The Italian version of the questionnaire appears to be psychometrically adequate for its use in clinical research

Quantum dots labelling allows detection of the homing of mesenchymal stem cells administered as immunomodulatory therapy in an experimental model of pancreatic islets transplantation

Cell transplantation is considered a promising therapeutic approach in several pathologies but still needs innovative and non-invasive imaging technologies to be validated. The use of mesenchymal stem cells (MSCs) attracts major interest in clinical transplantation thanks to their regenerative properties, low immunogenicity and ability to regulate immune responses. In several animal models, MSCs are used in co-transplantation with pancreatic islets (PIs) for the treatment of type I diabetes, supporting graft survival and prolonging normal glycaemia levels. In this study we investigated the homing of systemically administered MSCs in a rat model of pancreatic portal vein transplantation. MSCs labelled with quantum dots (Qdots) were systemically injected by tail vein and monitored by optical fluorescence imaging. The fluorescence signal of the liver in animals co-transplanted with MSCs and PIs was significantly higher than in control animals in which MSCs alone were transplanted. By using magnetic labelling of PIs, the homing of PIs into liver was independently confirmed. These results demonstrate that MSCs injected in peripheral blood vessels preferentially accumulate into liver when PIs are transplanted in the same organ. Moreover, we prove that bimodal MRI-fluorescence imaging allows specific monitoring of the fate of two types of cells

The transcriptional profile of adipose-derived stromal cells (ASC) mirrors the whitening of adipose tissue with age

Multipotent stem cells persist within the stromal vascular fraction (SVF) of adipose tissue during adulthood. These cells, commonly referred to as adipose-derived stromal cells (ASC), have been extensively investigated over the past years as a promising therapeutic tool based on their regenerative and immunomodulatory properties. However, how ASC might mirror the age-related alteration of the fat they reside in remains unclear. Herein, we show that inguinal adipose tissue in mice turns from brown/beige- to white-like with age and resident ASC readily mirror these changes both at mRNA and microRNA transcriptional level. Mechanistically, our data suggest that these brown/age-related changes in ASC transcription rely on changes in the activity of E2F1 and NFkB transcription factors