Effect of inborn pancreatic islet deficit in the Munich Wister Frömter rat

The total mass of pancreatic islet cells is a critical factor in glucose metabolic control. The aim of the present study was to investigate whether in the Munich Wistar Frömter (MWF) rat, beside a reduction in the number of nephrons, there are also alterations in the number of pancreatic islets and of β cell mass. We also examined glucose metabolism, both in normal conditions and following intravenous glucose injection. The number of islets per pancreas, estimated by morphometrical analysis, was significantly lower in MWF rats than in Wistar rats (3,501±1,285 vs. 7,259±2,330 islet/rat, respectively). Also the mean number of islets per gram of body weight was significantly lower in MWF rats than in Wistar rats (18±7 in MWF rats vs. 28±10 islets/g bw in Wistar rats). Morphometric analysis of β cell mass showed an average of 77.1±7% islet cells staining for insulin in MWF rats and 83.9±2.1% in the control Wistar rats. Despite the lower number of islets and β cells, MWF and Wistar rats had comparable fasting blood glucose levels but significant differences in blood glucose following an intraperitoneal glucose tolerance test. In summary, pancreatic islets of MWF and Wistar rats showed a marked difference in morphometrical characteristics. While this difference is not associated with blood glucose levels, glucose metabolism after IPGTT between MWF and Wistar rats is significantly different. These data suggest that an inborn deficit in β cell mass of about 60% is responsible for altered glucose metabolism and could favor the development of diabetes

Differentiation of Mesenchymal Stem Cells towards an insulin-releasing phenotype after co-culture with Pancreatic Islets

Transplantation of pancreatic islets has become a promising clinical option to treat patients with type 1 diabetes, alternative to the standard therapy with insulin injections. Islet transplantation is a minimally invasive therapeutic approach, and it allows a better metabolic control and a long-term insulin independence in more than 80% of patients (Ryan et al., 2002). However this therapeutic treatment has some side effects, such as the poor yield of pancreatic islet explants and even more the immune graft rejection, which have as a consequence the very limited lifespan of transplanted pancreatic islets. To avoid these side effects several strategies have been proposed and, besides the treatment with immunosuppressive drugs, promising results have been obtained with the use of Mesenchymal Stem cells (MSCs), already known in literature to be able to support the survival of many cell types (Scuteri et al., 2006). Several in vivo studies have demonstrated that the concurrent transplantation of pancreatic islets with MSCs reduces the number of islets required to achieve glycemic control in diabetic rats, but the mechanisms of these encouraging results are still unknown (Figliuzzi et al., 2009). For these reasons in this in vitro study we characterized the effect of co-culture of rat MSC on survival and functioning of rat pancreatic islets, by evaluating for 4 weeks: i) MSC adhesion to pancreatic islets; ii) viability of pancreatic islets co-cultured with MSCs; iii) the expression of insulin after co-culture; iv) the ability of co-cultured pancreatic islets to correctly adjust insulin release after variation of glucose concentration. Our results demonstrated that MSCs are able to adhere to pancreatic islets, but to increase only partly the pancreatic islet survival, which retain the ability to express and correctly release insulin after glucose variation in medium culture. Noteworthy that the insulin level in the medium of co-cultured pancreatic islets is always higher with respect to medium of pancreatic islets alone. The immunofluorescence analysis reveals that also MSCs (and not only pancreatic islets) are able to express insulin, but only in co-culture. These results, which justify the in vivo observation reported above, suggest that MSCs undergo to differentiation into a insulin-releasing phenotype after co-culture with pancreatic islets. We are now evaluating the molecular mechanisms which drive this effect, by analyzing the role of soluble factors and of proteins able to induce insulin expression. This study was granted by MIUR – FIRB Futuro in Ricerca 2008 RBFR08VSVI_001

Miniaturized Blood Pressure Telemetry System with RFID Interface

This work deals with the development and characterization of a potentially implantable blood pressure telemetry system, based on an active Radio-Frequency IDentification (RFID) tag, International Organization for Standardization (ISO) 15693 compliant. This approach aims to continuously measure the average, systolic and diastolic blood pressure of the small/medium animals. The measured pressure wave undergoes embedded processing and results are stored onboard in a non-volatile memory, providing the data under interrogation by an external RFID reader. In order to extend battery lifetime, RFID energy harvesting has been investigated. The paper presents the experimental characterization in a laboratory and preliminary in-vivo tests. The device is a prototype mainly intended, in a future engineered version, for monitoring freely moving test animals for pharmaceutical research and drug safety assessment purposes, but it could have multiple uses in environmental and industrial applications

Effect of the 3D Artificial Nichoid on the Morphology and Mechanobiological Response of Mesenchymal Stem Cells Cultured In Vitro

Stem cell fate and behavior are affected by the bidirectional communication of cells and their local microenvironment (the stem cell niche), which includes biochemical cues, as well as physical and mechanical factors. Stem cells are normally cultured in conventional two-dimensional monolayer, with a mechanical environment very different from the physiological one. Here, we compare culture of rat mesenchymal stem cells on flat culture supports and in the “Nichoid”, an innovative three-dimensional substrate micro-engineered to recapitulate the architecture of the physiological niche in vitro. Two versions of the culture substrates Nichoid (single-layered or “2D Nichoid” and multi-layered or “3D Nichoid”) were fabricated via two-photon laser polymerization in a biocompatible hybrid organic-inorganic photoresist (SZ2080). Mesenchymal stem cells, isolated from rat bone marrow, were seeded on flat substrates and on 2D and 3D Nichoid substrates and maintained in culture up to 2 weeks. During cell culture, we evaluated cell morphology, proliferation, cell motility and the expression of a panel of 89 mesenchymal stem cells’ specific genes, as well as intracellular structures organization. Our results show that mesenchymal stem cells adhered and grew in the 3D Nichoid with a comparable proliferation rate as compared to flat substrates. After seeding on flat substrates, cells displayed large and spread nucleus and cytoplasm, while cells cultured in the 3D Nichoid were spatially organized in three dimensions, with smaller and spherical nuclei. Gene expression analysis revealed the upregulation of genes related to stemness and to mesenchymal stem cells’ features in Nichoid-cultured cells, as compared to flat substrates. The observed changes in cytoskeletal organization of cells cultured on 3D Nichoids were also responsible for a different localization of the mechanotransducer transcription factor YAP, with an increase of the cytoplasmic retention in cells cultured in the 3D Nichoid. This difference could be explained by alterations in the import of transcription factors inside the nucleus due to the observed decrease of mean nuclear pore diameter, by transmission electron microscopy. Our data show that 3D distribution of cell volume has a profound effect on mesenchymal stem cells structure and on their mechanobiological response, and highlight the potential use of the 3D Nichoid substrate to strengthen the potential effects of MSC in vitro and in vivo

Mesenchymal stem cells help pancreatic islet transplantation to control type 1 diabetes

Islet cell transplantation has therapeutic potential to treat type 1 diabetes, which is characterized by autoimmune destruction of insulin-producing pancreatic islet β cells. It represents a minimal invasive approach for β cell replacement, but long-term blood control is still largely unachievable. This phenomenon can be attributed to the lack of islet vasculature and hypoxic environment in the immediate post-transplantation period that contributes to the acute loss of islets by ischemia. Moreover, graft failures continue to occur because of immunological rejection, despite the use of potent immunosuppressive agents. Mesenchymal stem cells (MSCs) have the potential to enhance islet transplantation by suppressing inflammatory damage and immune mediated rejection. In this review we discuss the impact of MSCs on islet transplantation and focus on the potential role of MSCs in protecting islet grafts from early graft failure and from autoimmune attack

Tumor interstitial fluid: misconsidered component of the internal milieu of a solid tumor.

The tumor interstitial fluid (TIF) is a fluid phase present in the extracellular space of all tumors whose importance in oncology is seldom recognized. In order to stimulate other researchers to give it the due importance, a review of the available data (including our own) is provided. An hypothesis is presented for the genesis, fate and role of the TIF in the processes of invasion, growth and metastatization. Open questions regarding the TIF's role in tumor response to therapy are raised