Research ArticleHEALTH AND MEDICINE

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

See allHide authors and affiliations

Science Advances  10 Jul 2019:
Vol. 5, no. 7, eaaw4357
DOI: 10.1126/sciadv.aaw4357
  • Fig. 1 Schematic of glucose-responsive charge-reversal polymers for insulin delivery.

    (A) Mechanism of glucose-sensitive charge reversal and enhanced insulin release from complex under a hyperglycemic state. The complex was prepared from a positively charged polymer and the negatively charged insulin via electrostatic interaction. (B) Representative fluorescence images of complex formed from poly(EDAAx-FPBAy) [green, fluorescein isothiocyanate (FITC)–labeled] and insulin (red, rhodamine B–labeled). Scale bar, 500 μm. (C) Representative images of the complex before (left) and after (right) treatment of glucose (400 mg/dl) for 3 hours at 37°C.

  • Fig. 2 The glucose binding and charge-switch study.

    (A to C) Glucose concentration–dependent glucose-binding ability of F-insulin (A), B-insulin (B), and N-insulin (C). The complexes were incubated in glucose solutions (100, 200, or 400 mg/dl). Data points are means ± SD (n = 3). (D and E) Hydrodynamic size distribution determined by DLS and representative TEM images of nanoparticles prepared from poly(EDAA0.4-FPBA0.6) (D) and poly(EDAA0.4-PBA0.6) (E). (F) Glucose concentration–dependent ζ potentials of nanoparticles prepared from poly(EDAA0.4-FPBA0.6) and poly(EDAA0.4-PBA0.6). Data points are means ± SD (n = 3). Statistical significance was calculated using Student’s t test. ***P < 0.001. NS, not significant.

  • Fig. 3 Glucose- and structure-dependent insulin release.

    (A and B) Glucose-dependent insulin release from F-insulin (A) and B-insulin (B) over time. Insulin was labeled with rhodamine B. The glucose concentrations were set to 0, 100, 200, and 400 mg/dl. Data points are means ± SD (n = 3). a.u., arbitrary units. (C) Cumulative insulin release profile of F-insulin. The complex was incubated in each solution for 10 min. Data points are means ± SD (n = 3). (D) Pulsatile insulin release from F-insulin by alternating the glucose concentration. The complex was incubated in each solution for 2 min. Data points are means ± SD (n = 3).

  • Fig. 4 In vivo evaluation of insulin complex for type 1 diabetic mice treatment.

    (A) BGLs of type 1 diabetic mice treated with subcutaneously injected native insulin, F-insulin, or B-insulin. PBS was used as a control. The insulin-equivalent dose was 80 U/kg. Data points are means ± SD (n = 5). Statistical significance between groups treated with F-insulin and native insulin was calculated. (B) Normoglycemic time of mice treated with subcutaneously injected F-insulin, B-insulin, and native insulin. Statistical significance was calculated. Data points are means ± SD (n = 5). (C) Live imaging of subcutaneously injected F-insulin and native insulin labeled with sulfo-Cy5. (D) IPGTT in diabetic mice at 3 hours after treatment of F-insulin or native insulin. Glucose dose was set to 1.5 g/kg. Healthy mice were used as control. Data points are means ± SD (n = 5). Statistical significance between F-insulin– and native insulin–treated groups was calculated. (E) Responsiveness to IPGTT in terms of the area under the curve (AUC) in 150 min, with the baseline set at the 0-min blood glucose reading. Data points are means ± SD (n = 5). Statistical significance between groups was calculated. (F) In vivo glucose-responsive insulin release triggered by intraperitoneal glucose injection at 4 hours after treatment of F-insulin at a dose of 80 U/kg. Glucose dose was set to 2 g/kg. Data points are means ± SD (n = 4 to 5). Statistical significance between the plasma insulin levels at various time points after glucose challenge and that at 0 min was calculated. Inset: Representative image of the resultant light yellow solution associated with enzyme-linked immunosorbent assay (ELISA) measurement. Plasma collected at 0, 10, 20, 30, 40, 60, 90, and 120 min after treatment of F-insulin was added to each well one by one from left to right. 5,5′-Tetramethylbenzidine (TMB) was used as the substrate of horseradish peroxidase, and the addition of sulfuric acid (0.6 N) turned the blue product of TMB to light yellow. (G) Representative scanning electron microscopy image of the MN arrays. Inset: Representative fluorescence image of the MNs loaded with F-insulin. Insulin was labeled with rhodamine B. Scale bar, 300 μm. (H) BGLs of type 1 diabetic mice treated with MN array patches loaded with insulin (MN-insulin) or F-insulin (MN–F-insulin) (2 mg of insulin per patch). Blank MN loaded with PBS was used as a negative control. One patch was applied to one mouse. Statistical significance between the groups treated with MN-insulin and MN–F-insulin was calculated. Data points are means ± SD (n = 5). (I) In vivo glucose-responsive insulin release triggered by intraperitoneal glucose injection at 3 hours after treatment of MN array patch load with F-insulin. Each mouse was treated with one patch containing 2 mg of insulin encapsulated in the complex. Glucose was given at 2 g/kg. Data points are means ± SD. (n = 4). Statistical significance between the plasma insulin levels at various time points after glucose challenge and that at 0 min was calculated. All the statistical analyses were performed by one-way analysis of variance (ANOVA) with a Tukey post hoc test or Student’s t test. *P < 0.05, **P < 0.01, and ***P < 0.001.

  • Fig. 5 In vivo evaluation of F-insulin for treatment of type 1 diabetic minipig.

    (A) BGLs of type 1 diabetic minipigs treated with native insulin or F-insulin. The insulin dose was set to 1 U/kg. The BGLs were measured continuously by CGMS. Each curve represents the BGL change obtained from a single minipig. The same color indicated the data from the same pig. Three pigs (designated as 1, 2, or 3) were used in this study. The black arrow indicated the injection of insulin or F-insulin. The orange arrows indicated the two meals for pigs. (B) Oral glucose tolerance test toward diabetic minipigs at 4 hours after treatment of F-insulin (0.5 U/kg). Glucose was given at 0.5 g/kg. (C) Intravenous glucose tolerance test in diabetic minipigs at 4 hours after treatment of F-insulin at a dose of 1 U/kg. Dextrose solution (5%) was intravenously infused at a dose of 0.75 g/kg. The rate of infusion was set to 1 liter/hour. Figures from left to right indicated pigs 1, 2, and 3, respectively.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/7/eaaw4357/DC1

    Scheme S1. Synthesis route of polymers.

    Fig. S1. Characterization of the complex.

    Fig. S2. 1H NMR spectra of various compounds synthesized.

    Fig. S3. In vitro insulin release studies.

    Fig. S4. Evaluation of insulin complexes in type 1 diabetic mice.

    Fig. S5. Host response and toxicity evaluation in diabetic mice.

    Fig. S6. The Masson’s trichrome staining sections of the skin with or without treatment.

    Fig. S7. The immunofluorescence staining sections of the skin with or without treatment.

    Fig. S8 Characterization of MN array patch.

    Fig. S9. Glucose challenge study in diabetic minipigs.

    Table S1. The BGLs of diabetic pigs.

  • Supplementary Materials

    This PDF file includes:

    • Scheme S1. Synthesis route of polymers.
    • Fig. S1. Characterization of the complex.
    • Fig. S2. 1H NMR spectra of various compounds synthesized.
    • Fig. S3. In vitro insulin release studies.
    • Fig. S4. Evaluation of insulin complexes in type 1 diabetic mice.
    • Fig. S5. Host response and toxicity evaluation in diabetic mice.
    • Fig. S6. The Masson’s trichrome staining sections of the skin with or without treatment.
    • Fig. S7. The immunofluorescence staining sections of the skin with or without treatment.
    • Fig. S8 Characterization of MN array patch.
    • Fig. S9. Glucose challenge study in diabetic minipigs.
    • Table S1. The BGLs of diabetic pigs.

    Download PDF

    Files in this Data Supplement:

Stay Connected to Science Advances

Navigate This Article