In vivo laboratory practicals in research-led teaching: An example using glucose tolerance tests in lean and obese mice

The use of animal models is an essential part of medical research and drug development. The essential skills required to be able to do such research includes experimental design, statistical analysis and the actual handling and treating of the animals (in vivo skills). The number of students in the U.K. receiving training in handling and experimenting on animals has declined rapidly in the last few decades which has led to initiatives to increase numbers of students with these skills to meet demand. Within the Department of Pharmacology and Therapeutics at King's College London, we run a course for 2nd year undergraduates entitled “Animal models of disease and injury”. This course not only covers the theoretical and ethical aspects of using animals in research, but also contains practical laboratory classes in which students get hands-on experience using animals. One of the laboratory classes we run is a glucose tolerance test in obese and lean mice. This is an example of research-led teaching which aims to develop research skills through engaging students in research like activities. In this paper, we outline the methodology of the glucose tolerance practical and highlight some of the skills we and the students think they gain by research-led teaching such as this

Mesenchymal stromal cells improve human islet function through released products and extracellular matrix

Aims: The aims of the present study were (i) to determine whether the reported beneficial effects of mesenchymal stromal cells (MSCs) on mouse islet function extend to clinically relevant human tissues (islets and MSCs), enabling translation into improved protocols for clinical human islet transplantation; and (ii) to identify possible mechanisms through which human MSCs influence human islet function.Materials and methods: Human islets were co-cultured with human adipose tissue-derived MSCs (hASCs) or pre-treated with its products – extracellular matrix (ECM) and annexin A1 (ANXA1). Mouse islets were pre-treated with mouse MSC-derived ECM. Islet insulin secretory function was assessed in vitro by radioimmunoassay. Quantitative RT-PCR was used to screen human adipMSCs for potential ligands of human islet G-protein-coupled receptors.Results: We show that co-culture with hASCs improves human islet secretory function in vitro, as measured by glucose-stimulated insulin secretion, confirming previous reports using rodent tissues. Furthermore, we demonstrate that these beneficial effects on islet function can be partly attributed to the MSC-derived products ECM and ANXA1.Conclusions: Our results suggest that hASCs have the potential to improve the quality of human islets isolated for transplantation therapy of Type 1 diabetes. Furthermore, it may be possible to achieve improvements in human islet quality in a cell-free culture system by using the MSC-derived products ANXA1 and ECM.</jats:p

SNAP-tag-enabled super-resolution imaging reveals constitutive and agonist-dependent trafficking of GPR56 in pancreatic β-cells

Objective: Members of the adhesion G protein-coupled receptor (aGPCR) subfamily are important actors in metabolic processes, with GPR56 (ADGRG1) emerging as a possible target for type 2 diabetes therapy. GPR56 can be activated by collagen III, its endogenous ligand, and by a synthetic seven amino-acid peptide (TYFAVLM; P7) contained within the GPR56 Stachel sequence. However, the mechanisms regulating GPR56 trafficking dynamics and agonist activities are not yet clear. Methods: Here, we introduced SNAPf-tag into the N-terminal segment of GPR56 to monitor GPR56 cellular activity in situ. Confocal and super-resolution microscopy were used to investigate the trafficking pattern of GPR56 in native MIN6 β-cells and in MIN6 β-cells where GPR56 had been deleted by CRISPR-Cas9 gene editing. Insulin secretion, changes in intracellular calcium, and β-cell apoptosis were determined by radioimmunoassay, single-cell calcium microfluorimetry, and measuring caspase 3/7 activities, respectively, in MIN6 β-cells and human islets. Results: SNAP-tag labelling indicated that GPR56 predominantly underwent constitutive internalisation in the absence of an exogenous agonist, unlike GLP-1R. Collagen III further stimulated GPR56 internalisation, whereas P7 was without significant effect. The overexpression of GPR56 in MIN6 β-cells did not affect insulin secretion. However, it was associated with reduced β-cell apoptosis, while the deletion of GPR56 made MIN6 β-cells more susceptible to cytokine-induced apoptosis. P7 induced a rapid increase in the intracellular calcium in MIN6 β-cells (in a GPR56-dependent manner) and human islets, and it also caused a sustained and reversible increase in insulin secretion from human islets. Collagen III protected human islets from cytokine-induced apoptosis, while P7 was without significant effect. Conclusions: These data indicate that GPR56 exhibits both agonist-dependent and -independent trafficking in β-cells and suggest that while GPR56 undergoes constitutive signalling, it can also respond to its ligands when required. We have also identified that constitutive and agonist-dependent GPR56 activation is coupled to protect β-cells against apoptosis, offering a potential therapeutic target to maintain β-cell mass in type 2 diabetes