Research ArticleDrug Delivery

An inflammation-targeting hydrogel for local drug delivery in inflammatory bowel disease

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Science Translational Medicine  12 Aug 2015:
Vol. 7, Issue 300, pp. 300ra128
DOI: 10.1126/scitranslmed.aaa5657
  • Fig. 1. IT-hydrogel targets drug release to the inflamed mucosa.

    (A) A lipophilic drug is loaded into IT-hydrogel during gelation. The drug integrates into the hydrophobic core of the lipid bilayer. Microfibers represent higher-order assemblies of extended bilayer structures, which are suspended in phosphate-buffered saline (PBS) to yield a mixture of microscopic hydrogel fiber particles of various sizes. (B) Negatively charged IT-hydrogel microfibers do not adhere to the intact mucosal surface. The inflamed mucosa is characterized by mucus depletion, accumulation of positively charged proteins, and increased permeability of the epithelial cell layer. Negatively charged IT-hydrogel microfibers adhere to the positively charged inflamed epithelium. Hydrolytic enzymes released by inflammatory cells degrade the gel, resulting in drug release. PMN, polymorphonuclear leukocytes. (C) Molecular structure of AP (top) and the assembled IT-hydrogel (bottom) demonstrating the alignment of the hydrophobic tails in the center and the hydrophilic heads on the outside of the bilayer. (D) AP before and after gelation. (E) Environmental scanning electron microscopy images of unloaded and Dex-loaded IT-hydrogel before suspension in PBS. (F) ζ Potential of IT-hydrogel (Gel) or gel loaded with Dex (Dex/gel), DiD (DiD/gel), or Dex + DiD [(Dex + DiD)/gel]. Data are means ± SD (n = 6 pooled from two experiments); P = 0.1485 determined by one-way analysis of variance (ANOVA). (G) Polarized optical microscopy image of IT-hydrogel suspended in PBS.

  • Fig. 2. Dex is efficiently encapsulated into IT-hydrogel and released by esterase activity and supernatant from macrophages.

    (A and B) Drug-loading and encapsulation efficiencies for 4 and 8% AP gelator with Dex-Pal at Dex equivalent of 5 and 10 mg/ml. (C) Esterase-responsive Dex release from IT-hydrogel. Esterase (T. lanuginosus lipase, 100 U/ml) was added on day 6. (D) Dex release from IT-hydrogel upon incubation with culture supernatant from activated mouse or human macrophages for 24 hours at 37°C. The 4% IT-hydrogel in (C) and (D) was loaded with Dex-Pal (Dex equivalent, 5 mg/ml). Data are means ± SD (n = 3, performed at least twice); P values in (D) were determined by Student’s t test with the Holm-Sidak method to correct for multiple comparisons.

  • Fig. 3. IT-hydrogel preferentially adheres to inflamed mucosa.

    (A) (DiD + Dex)–loaded 4% IT-hydrogel [(DiD + Dex)/gel] was incubated with uncoated, mucin-coated (simulating healthy epithelium), or transferrin-coated (simulating inflamed epithelium) surfaces at 37°C for 1 hour. Fluorescence images obtained after rinsing (left) were quantified using ImageJ software (right). Data are means ± SD (n = 9, triplicate samples, three images per sample); P values were determined by one-way ANOVA with Tukey post hoc test. aU, arbitrary unit. (B) The distal colon of wild-type (WT) mice with DSS-induced colitis and healthy controls was incubated ex vivo with (DiD + Dex)/gel at 37°C for 30 min and washed, and fluorescence was quantified using an IVIS imaging system (left). The same experimental setup compared colitic TRUC mice and age-matched Rag2/ mice without colitis (right). (C) WT mice with DSS-induced colitis and healthy controls received an enema of (DiD + Dex)/gel. The animals were sacrificed 12 hours later, and fluorescence of the distal colon was measured (left). The same experimental setup compared colitic TRUC and control Rag2/ mice (right). In (B) and (C), the total fluorescence intensity was determined in a standard-size region of interest (ROI) drawn around the individual colon pieces; data are means ± SEM (n = 5 to 7 mice per group); P values were determined by Student’s t test.

  • Fig. 4. Drug delivery via IT-hydrogel enema improves therapeutic efficacy when dosed every other day.

    (A) Colitic TRUC mice received enemas on days 1 and 3 after overnight (O/N) fasts; animals were sacrificed for analysis on day 5. (B) Histopathology scores after treatment with enemas of IT-hydrogel (Gel), free Dex, or Dex-loaded IT-hydrogel (Dex/gel, 70 μg of Dex equivalent per dose in both groups). Control mice received no treatment. Data are means ± SD (n = 10 mice per group). P = 0.0029 by one-way ANOVA; comparison of individual groups by Tukey post hoc test. (C) Representative hematoxylin and eosin (H&E) histology images of the experimental groups in (B). (D) Colon weight, MPO activity, and TNF mRNA levels in the distal colon measured in a second independent experiment. Data are means ± SD (n = 10 mice per group); P values were determined by one-way ANOVA with Tukey post hoc test. (E) TRUC mice received four daily intraperitoneal (i.p.) injections of free Dex (Dex-21 phosphate, 70 μg of Dex equivalent per dose) or PBS; animals were sacrificed on day 5. (F) Histopathology scores for mice in (E) (n = 9 mice per group). (G) Histopathology scores for TRUC mice treated with two enemas of Dex-Pal (70 μg of Dex equivalent per dose) in vehicle (5% ethanol + 5% Tween 80) or vehicle only (Control) (n = 8 mice per group) using the dosing regimen described in (A). Data in (F) and (G) are means ± SD; P values were determined by Student’s t test.

  • Fig. 5. Drug delivery via IT-hydrogel enema reduces systemic drug exposure.

    (A) Experimental design for the pharmacokinetic study. Colitic mice received a single enema of either free Dex or Dex-loaded IT-hydrogel (containing 70 μg of Dex equivalent) at 0 hour after an overnight fast. The serum Dex concentration was determined at 1, 2, 4, 6, 12, and 24 hours after enema, and the area under the curve (AUC) was calculated. (B) Results of the pharmacokinetic experiment described in (A) for WT mice with or without DSS-induced colitis and for TRUC mice compared with Rag2−/− controls. Data are means ± SD (n = 7 to 10 mice per group); P values were determined by Student’s t test.

  • Fig. 6. IT-hydrogel preferentially adheres to inflamed human colon mucosa.

    (A) Representative IVIS image of duplicate samples from endoscopically normal and inflamed sites after incubation with (DiD + Dex)/gel. (B) Fluorescence intensity values for individual patient biopsy samples from histologically normal or inflamed locations. Values were normalized by tissue dry weight; data are means of duplicate samples. (C) Paired fluorescence intensity values for the patients in (B). Lines connected the paired means of duplicate samples for individual patients (n = 6). The P value was determined by paired t test.

Supplementary Materials

  • www.sciencetranslationalmedicine.org/cgi/content/full/7/300/300ra128/DC1

    Methods

    Fig. S1. Additional in vitro characterization of IT-hydrogel.

    Fig. S2. IT-hydrogel lacks in vitro cytotoxicity against human colon epithelial cells.

    Fig. S3. IT-hydrogel preferentially adheres to positively charged substrates.

    Fig. S4. Fluorescent imaging demonstrates adhesion of IT-hydrogel to the inflamed mucosa.

    Fig. S5. Inflamed colon mucosa retains (DiD + Dex)–loaded IT-hydrogel, but not free dye.

    Fig. S6. The effect of free Dex or Dex-loaded IT-hydrogel enemas on barrier function in vivo.

    Table S1. Clinical data of all UC patients (n = 11) recruited for this study.

    References (3541)

  • Supplementary Material for:

    An inflammation-targeting hydrogel for local drug delivery in inflammatory bowel disease

    Sufeng Zhang, Joerg Ermann, Marc D. Succi, Allen Zhou, Matthew J. Hamilton, Bonnie Cao, Joshua R. Korzenik, Jonathan N. Glickman, Praveen K. Vemula, Laurie H. Glimcher, Giovanni Traverso,* Robert Langer,* Jeffrey M. Karp*

    *Corresponding author. E-mail: rlanger{at}mit.edu (R.L.); jmkarp{at}partners.org (J.M.K.); ctraverso{at}partners.org (G.T.)

    Published 12 August 2015, Sci. Transl. Med. 7, 300ra128 (2015)
    DOI: 10.1126/scitranslmed.aaa5657

    This PDF file includes:

    • Methods
    • Fig. S1. Additional in vitro characterization of IT-hydrogel.
    • Fig. S2. IT-hydrogel lacks in vitro cytotoxicity against human colon epithelial cells.
    • Fig. S3. IT-hydrogel preferentially adheres to positively charged substrates.
    • Fig. S4. Fluorescent imaging demonstrates adhesion of IT-hydrogel to the inflamed mucosa.
    • Fig. S5. Inflamed colon mucosa retains (DiD + Dex)–loaded IT-hydrogel, but not free dye.
    • Fig. S6. The effect of free Dex or Dex-loaded IT-hydrogel enemas on barrier function in vivo.
    • Table S1. Clinical data of all UC patients (n = 11) recruited for this study.
    • References (3541)

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