Glucose-responsive Insulin Research Articles

Targeted Derivation of Organotypic Glucose- and GLP-1-Responsive β Cells Prior to Transplantation into Diabetic Recipients.

SummaryGeneration of functional β cells from pluripotent sources would accelerate diagnostic and therapeutic applications for diabetes research and therapy. However, it has been challenging to generate competent β cells with dynamic insulin-secretory capacity to glucose and incretin stimulations. We introduced transcription factors, critical for β-cell development and function, in differentiating human induced pluripotent stem cells (PSCs) and assessed the impact on the functionality of derived β-cell (psBC) progeny. A perifusion system revealed stepwise transduction of the PDX1, NEUROG3, and MAFA triad (PNM) enabled in vitro generation of psBCs with glucose and GLP-1 responsiveness within 3 weeks. PNM transduction upregulated genes associated with glucose sensing, insulin secretion, and β-cell maturation. In recipient diabetic mice, PNM-transduced psBCs showed glucose-responsive insulin secretion as early as 1 week post transplantation. Thus, enhanced pre-emptive β-cell specification of PSCs by PNM drives generation of glucose- and incretin-responsive psBCs in vitro, offering a competent tissue-primed biotherapy.

Charge-switchable polymeric complex for glucose-responsive insulin delivery in mice and pigs.

Glucose-responsive insulin delivery systems with robust responsiveness that has been validated in animal models, especially in large animal models, remain elusive. Here, we exploit a new strategy to form a micro-sized complex between a charge-switchable polymer with a glucose-sensing moiety and insulin driven by electrostatic interaction. Both high insulin loading efficiency (95%) and loading capacity (49%) can be achieved. In the presence of a hyperglycemic state, the glucose-responsive phenylboronic acid (PBA) binds glucose instantly and converts the charge of the polymeric moiety from positive to negative, thereby enabling the release of insulin from the complex. Adjusting the ratio of the positively charged group to PBA achieves inhibited insulin release from the complex under normoglycemic conditions and promoted release under hyperglycemic conditions. Through chemically induced type 1 diabetic mouse and swine models, in vivo hyperglycemia-triggered insulin release with fast response is demonstrated after the complex is administrated by either subcutaneous injection or transdermal microneedle array patch.

Smart Microneedle Fabricated with Silk Fibroin Combined Semi-interpenetrating Network Hydrogel for Glucose-Responsive Insulin Delivery.

Microneedle (MN) technology, which can transdermally deliver insulin in a noninvasive manner, offers a promising way to replace subcutaneous self-injection for diabetes management. Hydrogel is an attractive candidate for MN fabrication because of its biocompatibility, controllable degradability, and possibility to achieve sustained as well as stimuli-responsive drug delivery. Herein, we report a smart MN composed of a semi-interpenetrating network (semi-IPN) hydrogel prepared by biocompatible silk fibroin (SF) and phenylboronic acid/acrylamide for glucose-responsive insulin delivery. Six fabrication methods were investigated to maintain the glucose sensitivity of the hydrogel while avoiding deformation during fabrication. The optimized method was to fabricate smart MNs using a two-layer strategy, with a needle region formed by the SF combined semi-IPN hydrogel and the base layer fabricated by SF. The hybrid MN autonomously released insulin well-correspondent to the glucose change pattern via the regulation of the skin layer formed on the surface. Furthermore, this hybrid MN retained its original needle shape after 1 week in aqueous system, thus eliminating the safety concerns associated with dissolving MNs and suggesting the possibility for sustained delivery. This nondegradable smart MN is promising to provide on-demand insulin in a long-acting, painless, and convenient way.

Management of Glucose Control in Noncritically Ill, Hospitalized Patients Receiving Parenteral and/or Enteral Nutrition: A Systematic Review.

Hyperglycemia is a common occurrence in hospitalized patients receiving parenteral and/or enteral nutrition. Although there are several approaches to manage hyperglycemia, there is no consensus on the best practice. We systematically searched PubMed, Embase, Cochrane Central, and ClinicalTrials.gov to identify records (published or registered between April 1999 and April 2019) investigating strategies to manage glucose control in adults receiving parenteral and/or enteral nutrition whilst hospitalized in noncritical care units. A total of 15 completed studies comprising 1170 patients were identified, of which 11 were clinical trials and four observational studies. Diabetes management strategies entailed adaptations of nutritional regimens in four studies, while the remainder assessed different insulin regimens and administration routes. Diabetes-specific nutritional regimens that reduced glycemic excursions, as well as algorithm-driven insulin delivery approaches that allowed for flexible glucose-responsive insulin dosing, were both effective in improving glycemic control. However, the assessed studies were, in general, of limited quality, and we see a clear need for future rigorous studies to establish standards of care for patients with hyperglycemia receiving nutrition support.

Glucose-Responsive Insulin Through Bioconjugation Approaches

Although insulin analogs have markedly improved glycemic control for people with diabetes, glycemic excursions still cause major health problems and complications. In particular, the narrow therapeutic window of current insulin therapy makes it extremely difficult to maintain normoglycemia without risking severe hypoglycemia. Currently, there are no FDA-approved insulin therapeutics whose bioactivity is regulated by blood glucose levels. This review discusses recent progress on developing glucose-responsive insulin (GRI) bioconjugates without the need of exogenous matrices. Through this approach, tremendous efforts have been made over the years to demonstrate the promise of better glycemic control and reduced risk of hypoglycemia. Last, we discuss future directions of GRI development with a goal to maximize the glucose responsiveness.

1103-P: Glucose-Responsive Insulin: An Unprecedented Cleavable Linker Concept

Achieving the optimal combination of multiple glucose measurements and insulin injections provides a complex daily situation for most insulin-dependent diabetes patients with currently available insulin products. To date, several fast-acting and long-acting insulins have been developed. However, while the pharmacokinetic profiles have been optimized, it has remained an elusive goal for decades to develop a Glucose Responsive Insulin (GRI), which can be responsive to the fluctuations in blood glucose concentrations during the day. Here we present an unprecedented GRI concept. The concept is based on the hydrolysis of a cleavable linker that is covalently bound to insulin. The chemical nature of this central linker is designed to rapidly release active insulin when glucose rises above euglycemia (5 mM), and this release of active insulin will increase with increasing blood glucose concentration. The second element of the concept is an albumin-mediated inactivation of the GRI by lipidation. After injection, the GRI will bind to albumin and circulate as a depot, resulting in a slow release of insulin like seen with other basal insulins such as insulin Detemir. At the linker level, we have tested three concentrations of glucose, and glucose responsiveness was demonstrated by a decrease in reaction time with increasing glucose concentration. Moreover, fully conjugated GRI molecules were tested in 90% pancreatectomized rats, a model of type 1 diabetes, demonstrating significant and long-lasting glucose lowering effect as compared to control. Overall, we have demonstrated the feasibility of providing a GRI approach, which combines the properties of a basal insulin with that of a bolus insulin. With the circulating depot approach the concept also holds a promise for liver preference. Ultimately our approach could provide a safe insulin for the treatment of insulin-dependent diabetes with very low risk of side effects. Disclosure K. Mannerstedt: Employee; Self; Gubra. E. Engholm: Employee; Self; Gubra. N.K. Mishra: Employee; Self; Gubra. M. Lundh: Employee; Self; Gubra. N. Buch-Månson: None. L.N. Fink: Employee; Self; Gubra. Stock/Shareholder; Self; Novo Nordisk A/S. S.L. Pedersen: None. P.J. Pedersen: Employee; Self; Gubra. P. Le-Huu: Employee; Self; Gubra, Novo Nordisk A/S. Employee; Spouse/Partner; Novo Nordisk A/S. J. Lai: Employee; Self; Gubra. K.J. Jensen: Consultant; Self; Gubra. Stock/Shareholder; Self; Gubra. K. Fosgerau: Stock/Shareholder; Self; Gubra.

331-LB: A Switch in Nutrient Sensing Controls Functional Maturation of Pancreatic Beta Cells

A drastic transition at birth, from constant maternal nutrient supply in-utero to intermittent postnatal feeding, requires functional changes in the metabolic system. Considering their central role in controlling metabolic homeostasis, little is known about how beta-cells adjust to the new nutritional challenge. Our experiments show that after birth beta-cells undergo a functional shift from amino acids- to glucose-stimulated insulin secretion. Moreover, a change in mTORC1 activity, from dependence on amino acids in the amino acid-rich environment in-utero to a postnatal dependence on glucose, corresponds with the initiation of glucose-responsive insulin secretion. Disrupting nutrient sensitivity of mTORC1 in mature beta-cells, via deletion of leucine-responsive inhibitors Sestrin1 and Sestrin2, reverts beta-cells to an immature state. Finally, manipulating mTORC1 nutrient sensitivity in stem-cell-derived beta-cells in-vitro shifts them from constitutive to glucose-dependent insulin secretion. These results reveal a post-transcriptional mechanism where nutritional environment and mTORC1 signaling regulate glucose responsiveness, thereby promoting beta-cell maturation. Disclosure A. Helman: None.

Glucose transporter inhibitor-conjugated insulin mitigates hypoglycemia

Insulin therapy in the setting of type 1 and advanced type 2 diabetes is complicated by increased risk of hypoglycemia. This potentially fatal complication could be mitigated by a glucose-responsive insulin analog. We report an insulin-facilitated glucose transporter (Glut) inhibitor conjugate, in which the insulin molecule is rendered glucose-responsive via conjugation to an inhibitor of Glut. The binding affinity of this insulin analog to endogenous Glut is modulated by plasma and tissue glucose levels. In hyperglycemic conditions (e.g., uncontrolled diabetes or the postprandial state), the in situ-generated insulin analog-Glut complex is driven to dissociate, freeing the insulin analog and glucose-accessible Glut to restore normoglycemia. Upon overdose, enhanced binding of insulin analog to Glut suppresses the glucose transport activity of Glut to attenuate further uptake of glucose. We demonstrate the ability of this insulin conjugate to regulate blood glucose levels within a normal range while mitigating the risk of hypoglycemia in a type 1 diabetic mouse model.

Phenylboronic acid functionalized silica nanoparticles with enlarged ordered mesopores for efficient insulin loading and controlled release

Mesoporous silica particles have been extensively used to construct various drug delivery systems. An optimized design of pore size, surface functionalization and pore structure, is still needed for further application, especially for use as biomacromolecules carriers. Herein, one intelligent glucose-responsive insulin delivery system Insulin@ZnO-P@G-MSP was constructed based on mesoporous silica nanoparticles with large ordered mesopores (>5 nm) and small particle sizes (∼150 nm), combined with phenylboronic acids as glucose-responsive units and zinc oxide nanoparticles as the capping agents. The release characteristics of this system showed a positive correlation with the species and concentration of the saccharides and could be switched on and off by adjusting the glucose concentration. The stable release rate in the serum and good biocompatibility with liver cells illustrated the feasibility of this system in further biological applications. This work demonstrates an innovative approach to the development of a biomolecules delivery system by introducing mesoporous silica particles with large ordered mesopores and nanometer-scale particle sizes.

Injectable dual glucose-responsive hydrogel-micelle composite for mimicking physiological basal and prandial insulin delivery

For type 1 and advanced type 2 diabetic patients, insulin replacement therapy with simulating on-demand prandial and basal insulin secretion is the best option for optimal glycemic control. However, there is no insulin delivery system yet could mimic both controlled basal insulin release and rapid prandial insulin release in response to real-time blood glucose changes. Here we reported an artificial insulin delivery system, mimicking physiological basal and prandial insulin secretion, to achieve real-time glycemic control and reduce risk of hypoglycemia. A phenylboronic acid (PBA)/galactosyl-based glucose-responsive insulin delivery system was prepared with insulin-loaded micelles embedded in hydrogel matrix. At the hyperglycemic state, both the hydrogel and micelles could swell and achieve rapid glucose-responsive release of insulin, mimicking prandial insulin secretion. When the glucose level returned to the normal state, only the micelles partially responded to glucose and still released insulin gradually. The hydrogel with increased crosslinking density could slow down the diffusion speed of insulin inside, resulting in controlled release of insulin and simulating physiological basal insulin secretion. This hydrogel-micelle composite insulin delivery system could quickly reduce the blood glucose level in a mouse model of type 1 diabetes, and maintain normal blood glucose level without hypoglycemia for about 24 h. This kind of glucose-responsive hydrogel-micelle composite may be a promising candidate for delivery of insulin in the treatment of diabetes.

A polysaccharide-based micelle-hydrogel synergistic therapy system for diabetes and vascular diabetes complications treatment

Various glucose-sensitive drug delivery platforms have been developed recently to treat diabetes. However, there is much less work has been reported on treatment of diabetes and vascular diabetes complications simultaneously. In this work, a novel polysaccharide-based micelle-hydrogel synergistic therapy system was fabricated to address this limitation. Zwitterionic dialdehyde starch-based micelles (SB-DAS-VPBA) were synthesized via single electron transfer-living radical polymerization (SET-LRP). Hydrophilic segment sulfobetaine (SB) and hydrophobic segment 4‑vinylphenylboronic acid (VPBA) were grafted to the dialdehyde starch (DAS) backbones. Then, chitosan/dialdehyde starch derivatives (CS/SB-DAS-VPBA) micelle-hydrogel was synthesized by Schiff-base bonds. Insulin and nattokinase were loaded to obtain the micelle-hydrogel synergistic therapy system. In vitro drug delivery and blood clots dissolution behaviors were determined. Results suggest that the micelle-hydrogel synergistic therapy system not only possesses glucose-responsive insulin delivery property, but also provides good thrombolytic capacity. Thus, this micelle-hydrogel synergistic therapy system can be used as a platform for diabetes and vascular diabetes complications treatment.

The Official Journal of ATTD Advanced Technologies & Treatments for Diabetes Conference Berlin, Germany—February 20–23, 2019

The Official Journal of ATTD Advanced Technologies &amp; Treatments for Diabetes Conference <i>Berlin, Germany—February 20–23, 2019</i>

Copolymers containing carbohydrates and other biomolecules: design, synthesis and applications.

Glycopolymers are synthetic polymers containing pendant carbohydrate groups. Other biological compounds can be incorporated into glycopolymers to prepare both random and block copolymers aimed at bio-related applications: boronic acid can be introduced as a functional group to obtain crosslinked hydrogels; cholesterol and bile acids can be introduced to render the polymers more hydrophobic for the formation of micelles. Sugar-containing block copolymers with biocompatible blocks such as polypeptides, poly(ethylene glycol), poly(lactic acid) and poly(ε-caprolactone) were also prepared for potential application in drug carriers. These glycopolymers interact with lectins or lectin-containing surfaces as natural carbohydrate mimics. This review highlights the recent progress in the synthesis of random or block glycopolymers. Examples of the applications of glycopolymers in the separation and removal of toxins and bacteria, tumor cell recognition and glucose-responsive insulin delivery are presented and discussed.

Glucose and H2O2 dual-sensitive nanogels for enhanced glucose-responsive insulin delivery.

Diabetes is a chronic metabolic disorder disease characterized by high blood glucose levels and has become one of the most serious threats to human health. In recent decades, a number of insulin delivery systems, including bulk gels, nanogels, and polymeric micelles, have been developed for the treatment of diabetes. Herein, a kind of glucose and H2O2 dual-responsive polymeric nanogel was designed for enhanced glucose-responsive insulin delivery. The polymeric nanogels composed of poly(ethylene glycol) and poly(cyclic phenylboronic ester) (glucose and H2O2 dual-sensitive groups) were synthesized by a one-pot thiol-ene click chemistry approach. The nanogels displayed glucose-responsive release of insulin and the release rate could be promoted by the incorporation of glucose oxidase (GOx), which generated H2O2 at high glucose levels and H2O2 further oxidizes and hydrolyzes the phenylboronic ester group. The nanogels have characteristics of long blood circulation time, a fast response to glucose, and excellent biocompatibility. Moreover, subcutaneous delivery of insulin to diabetic mice with the insulin/GOx-loaded nanogels presented an effective hypoglycemic effect compared to that of injection of insulin or insulin-loaded nanogels. This kind of nanogel would be a promising candidate for the delivery of insulin in the future.

Charge-switchable polymeric complex for glucose-responsive insulin delivery in mice and pigs

Charge-switchable polymeric complex for glucose-responsive insulin delivery in mice and pigs

Gold nanoclusters for controlled insulin release and glucose regulation in diabetes.

Diabetes has become the third threat to public health worldwide. Traditional treatments of diabetes require frequent blood glucose testing and insulin injections, which not only bring great pain to patients but also exhibit difficulty in controlling the blood glucose accurately. In order to solve these problems, we developed a smart glucose-responsive insulin delivery system responding to the environmental glucose concentration based on gold nanoclusters (GNCs). First, we prepared GNCs as high drug-loading nanocarriers, and we decorated GNCs with phenylboronic acid molecules (4-carboxyphenylboronic acid (PBA) and 4-carboxy-3-fluorophenylboronic acid (FPBA)) as responsive ligands; then, we grafted insulin on the surface to form glucose-responsive insulin-release nanocomplexes GNC-PBA-Ins and GNC-FPBA-Ins, respectively. In the in vitro test, these complexes exhibited high sensitivity to glucose concentrations and rapidly released insulin in a hyperglycemic state. In type 1 diabetic mice in vivo, these complexes could maintain the blood glucose levels of mice in a normoglycemic range for up to 48 h without peaks of hyperglycemia or hypoglycemia, where the GNC-FPBA-Ins complex showed a better regulation of glucose than the GNC-PBA-Ins complex. These gold nanocluster systems mimic the function of the natural pancreas for blood glucose control, which has great potentials for the diagnosis and treatment of diabetes in the future.

A forskolin-conjugated insulin analog targeting endogenous glucose-transporter for glucose-responsive insulin delivery.

Insulin administration for the management of diabetes is accompanied by hypoglycemia, which is expected to be mitigated by glucose-responsive smart insulin that has self-regulation ability in response to blood glucose level (BGL) fluctuation. Here, we have prepared a new insulin analog by modifying insulin with forskolin (designated as insulin-F), a glucose-transporter (Glut) inhibitor. In vitro, insulin-F is capable of binding to Glut on erythrocyte ghosts, which can be inhibited by glucose and cytochalasin B. Upon subcutaneous injection in type 1 diabetic mice, insulin-F maintains BGLs below 200 mg mL-1 for up to 10 h, and achieves 20 h with two sequential injections. Moreover, insulin-F also binds to endogenous Gluts. Upon a glucose challenge, the elevated level of glucose competitively replaces and liberates insulin-F that binds to Glut, rapidly restoring BGLs to the normal range.

Engineering synthetic artificial pancreas using chitosan hydrogels integrated with glucose-responsive microspheres for insulin delivery

The closed-loop delivery of insulin in response to change of the blood glucose level and long-term supply of insulin are both important for diabetes patients. However, combination of these two goals in a chemically controlled implantable system is still challenging yet highly desirable. The purpose of the present study is to design a synthetic artificial pancreas by integration of chitosan hydrogels with insulin-loaded glucose-responsive microspheres to deliver insulin in a close-looped and long-term way for diabetes care. Glucose-responsive insulin-loaded microspheres were firstly fabricated via a high-speed shear-emulsion based crosslinking method and then embedded into chitosan hydrogels to make a scaffold-based synthetic artificial pancreas. In vitro experiments indicated the scaffold exhibited a longer insulin supply as well as a lower burst release compared with free microspheres, and could keep the glucose-responsive insulin release property inherited from the corresponding microspheres even after 12 day-release. The released insulin was proved to remain active, and the culture of HDF cells on the scaffold showed good cell proliferation during 7 days incubation. These results suggested the scaffold-based synthetic artificial pancreas have great promise in the application of insulin delivery.

A biomimetic receptor for glucose.

Specific molecular recognition is routine for biology, but has proved difficult to achieve in synthetic systems. Carbohydrate substrates are especially challenging, because of their diversity and similarity to water, the biological solvent. Here we report a synthetic receptor for glucose, which is biomimetic in both design and capabilities. The core structure is simple and symmetrical, yet provides a cavity which almost perfectly complements the all-equatorial β-pyranoside substrate. The receptor's affinity for glucose, at Ka ~ 18,000 M-1, compares well with natural receptor systems. Selectivities also reach biological levels. Most other saccharides are bound approximately 100 times more weakly, while non-carbohydrate substrates are ignored. Glucose-binding molecules are required for initiatives in diabetes treatment, such as continuous glucose monitoring and glucose-responsive insulin. The performance and tunability of this system augur well for such applications.

Is an artificial pancreas (closed-loop system) for Type 1 diabetes effective?

The artificial pancreas is now a viable treatment option for people with Type 1 diabetes and has demonstrated improved glycaemic outcomes while also reducing the onus of self-management of Type 1 diabetes. Closed-loop glucose-responsive insulin delivery guided by real-time sensor glucose readings can accommodate highly variable day-to-day insulin requirements and reduce the hypoglycaemia risk observed with tight glycaemic control in Type 1 diabetes. In 2011, the James Lind Alliance research priorities for Type 1 diabetes were produced and priority 3 was to establish whether an artificial pancreas (closed-loop system) for Type 1 diabetes is effective. This review focuses on the progress that has been made in the evolution of closed-loop systems as an effective treatment option for Type 1 diabetes. Development of closed-loop systems has advanced from feasibility evaluations in highly supervised settings over short periods, to clinical studies in free-living, unsupervised conditions lasting several months. The approval in the USA of the first hybrid closed-loop system (MiniMed® 670G pump, Medtronic, Northridge, CA, USA) in 2016 for use in Type 1 diabetes reflects these advancements. We discuss the evidence from clinical studies that closed-loop systems are effective with improved glycaemic outcomes, reduced hypoglycaemia and had positive end-user acceptance in children, adolescents, adults and pregnant women with Type 1 diabetes. We also present the outlook for future closed-loop systems in the treatment of Type 1 diabetes and identify the challenges facing the wide-spread clinical adoption of this technology.