Challenges in stem cell-derived islet replacement therapy can be overcome

In this Commentary, we echo the conclusions of a recent review titled “ The promise of stem cell-derived islet replacement therapy,” which highlighted recent advances in producing glucose responsive “islets” from stem cells and the benefits of their use in islet transplant therapy in type 1 diabetes (T1D). The review also outlined the status of clinical islet transplantation and the challenges that have prevented it from reaching its full therapeutic promise. We agree with the conclusions of the review and suggest that the identified challenges may be overcome by using the eye anterior chamber as an islet transplant site. We anticipate that the combination of stem cell-derived islets and intraocular transplant could help this promising T1D therapy reach full fruition

Islet Transplantation to the Anterior Chamber of the Eye—A Future Treatment Option for Insulin-Deficient Type-2 Diabetics? A Case Report from a Nonhuman Type-2 Diabetic Primate

10.1177/0963689720913256Cell Transplantation2

Investigation of SNARE-Mediated Membrane Fusion Mechanism Using Atomic Force Microscopy

Membrane fusion is driven by specialized proteins that reduce the free energy penalty for the fusion process. In neurons and secretory cells, soluble N-ethylmaleimide-sensitive factor-attachment protein (SNAP) receptors (SNAREs) mediate vesicle fusion with the plasma membrane during vesicular content release. Although, SNAREs have been widely accepted as the minimal machinery for membrane fusion, the specific mechanism for SNARE-mediated membrane fusion remains an active area of research. Here, we summarize recent findings based on force measurements acquired in a novel experimental system that uses atomic force microscope (AFM) force spectroscopy to investigate the mechanism(s) of membrane fusion and the role of SNAREs in facilitating membrane hemifusion during SNARE-mediated fusion. In this system, protein-free and SNARE-reconstituted lipid bilayers are formed on opposite (trans) substrates and the forces required to induce membrane hemifusion and fusion or to unbind single v-/t-SNARE complexes are measured. The obtained results provide evidence for a mechanism by which the pulling force generated by interacting trans-SNAREs provides critical proximity between the membranes and destabilizes the bilayers at fusion sites by broadening the hemifusion energy barrier and consequently making the membranes more prone to fusion

Challenges in stem cell-derived islet replacement therapy can be overcome

In this Commentary, we echo the conclusions of a recent review titled “ The promise of stem cell-derived islet replacement therapy,” which highlighted recent advances in producing glucose responsive “islets” from stem cells and the benefits of their use in islet transplant therapy in type 1 diabetes (T1D). The review also outlined the status of clinical islet transplantation and the challenges that have prevented it from reaching its full therapeutic promise. We agree with the conclusions of the review and suggest that the identified challenges may be overcome by using the eye anterior chamber as an islet transplant site. We anticipate that the combination of stem cell-derived islets and intraocular transplant could help this promising T1D therapy reach full fruition

Transplantation into the Anterior Chamber of the Eye for Longitudinal, Non-invasive <em>In vivo</em> Imaging with Single-cell Resolution in Real-time

Intravital imaging has emerged as an indispensable tool in biological research. In the process, many imaging techniques have been developed to study different biological processes in animals non-invasively. However, a major technical limitation in existing intravital imaging modalities is the inability to combine non-invasive, longitudinal imaging with single-cell resolution capabilities. We show here how transplantation into the anterior chamber of the eye circumvents such significant limitation offering a versatile experimental platform that enables non-invasive, longitudinal imaging with cellular resolution in vivo. We demonstrate the transplantation procedure in the mouse and provide representative results using a model with clinical relevance, namely pancreatic islet transplantation. In addition to enabling direct visualization in a variety of tissues transplanted into the anterior chamber of the eye, this approach provides a platform to screen drugs by performing long-term follow up and monitoring in target tissues. Because of its versatility, tissue/cell transplantation into the anterior chamber of the eye not only benefits transplantation therapies, it extends to other in vivo applications to study physiological and pathophysiological processes such as signal transduction and cancer or autoimmune disease development

Effect of Arginase-1 Inhibition on the Incidence of Autoimmune Diabetes in NOD Mice

Metabolism of the amino acid L-arginine is implicated in many physiological and pathophysiological processes including autoimmune conditions such as type 1 diabetes (T1D). Alternate arginine metabolism through the citrulline-nitric oxide (NO) or the ornithine pathways can lead to proinflammatory or immune regulatory effects, respectively. In this report, we blocked the arginine-ornithine metabolic pathway by inhibiting the enzyme arginase-1 with Nω-hydroxy-nor-arginine (nor-NOHA) to make arginine more available to the alternate citrulline pathway for augmented NO production and increased incidence of autoimmune T1D in female non-obese diabetic (NOD) mice. Unexpectedly, mice receiving nor-NOHA did not develop diabetes although increased NO production is proinflammatory and expected to increase diabetes incidence. These results warrant further studies of the mechanism of action of nor-NOHA, and highlight its potential as a therapeutic agent for the treatment or prevention of T1D

Force Spectroscopy of LFA-1 and Its Ligands, ICAM-1 and ICAM-2

Single-molecule measurements of the interaction of leukocyte function-associated antigen-1 (LFA-1), expressed on Jurkat T cells, with intercellular adhesion molecules-1 and -2 (ICAM-1 and ICAM-2) were conducted using atomic force microscopy (AFM). The force spectra (i.e., unbinding force versus loading rate) of both the LFA-1/ICAM-1 and LFA-1/ICAM-2 interactions were acquired at a loading rate range covering 3 orders of magnitude (50–60 000 pN/s) and revealed a fast loading regime and a slow loading regime. This indicates that the dissociation of both complexes involves overcoming a steep inner and a wide outer activation barrier. LFA-1 binding to ICAM-1 and ICAM-2 was strengthened in the slow loading regime by the addition of Mg(2+). Differences in the dynamic strength of the LFA-1/ICAM-1 and LFA-1/ICAM-2 interactions can be attributed to the presence of wider barriers in the ICAM-2 complex, making it more responsive to a pulling force than the ICAM-1 complex

Exploring Computational Data Amplification and Imputation for the Discovery of Type 1 Diabetes (T1D) Biomarkers from Limited Human Datasets

Background: Type 1 diabetes (T1D) is a devastating disease with serious health complications. Early T1D biomarkers that could enable timely detection and prevention before the onset of clinical symptoms are paramount but currently unavailable. Despite their promise, omics approaches have so far failed to deliver such biomarkers, likely due to the fragmented nature of information obtained through the single omics approach. We recently demonstrated the utility of parallel multi-omics for the identification of T1D biomarker signatures. Our studies also identified challenges. Methods: Here, we evaluated a novel computational approach of data imputation and amplification as one way to overcome challenges associated with the relatively small number of subjects in these studies. Results: Using proprietary algorithms, we amplified our quadra-omics (proteomics, metabolomics, lipidomics, and transcriptomics) dataset from nine subjects a thousand-fold and analyzed the data using Ingenuity Pathway Analysis (IPA) software to assess the change in its analytical capabilities and biomarker prediction power in the amplified datasets compared to the original. These studies showed the ability to identify an increased number of T1D-relevant pathways and biomarkers in such computationally amplified datasets, especially, at imputation ratios close to the “golden ratio” of 38.2%:61.8%. Specifically, the Canonical Pathway and Diseases and Functions modules identified higher numbers of inflammatory pathways and functions relevant to autoimmune T1D, including novel ones not identified in the original data. The Biomarker Prediction module also predicted in the amplified data several unique biomarker candidates with direct links to T1D pathogenesis. Conclusions: These preliminary findings indicate that such large-scale data imputation and amplification approaches are useful in facilitating the discovery of candidate integrated biomarker signatures of T1D or other diseases by increasing the predictive range of existing data mining tools, especially when the size of the input data is inherently limited