Biocompatibility and function of microencapsulated pancreatic islets

Marina Figliuzzi, Tiziana Plati, Roberta Cornolti, Federica Adobati, Arianna Fagiani, Lisa Rossi, Giuseppe Remuzzi, Andrea Remuzzi

Research output: Contribution to journalArticlepeer-review

Abstract

Encapsulation of pancreatic islets in alginate is used to protect against xenogenic rejection in different animal models. In this study, several factors, including differences in alginate composition, the presence or absence of xenogenic islet tissue and a transient immunosuppression, were investigated in a model of bovine islet transplantation in rats. A pure alginate with predominantly guluronic acid (Manugel) and an ultrapure low viscosity guluronic acid alginate (UP-LVG) were used. When microcapsules of Manugel or UP-LVG containing 16,000 bovine islet equivalents were transplanted in diabetic rats, we observed normoglycemia for 8.3 ± 0.7 (range 6-12 days) and 7.5 ± 0.2 days (range 7-8 days) on average, respectively. To ameliorate immunoprotection of alginate microcapsules we repeated the same experiments using transient immunosuppressive therapy. Low doses of cyclosporin A (CyA) administered for 18 days after implantation increased the time in normoglycemia, which averaged 27 ± 3 days (range 8-55 days) in Manugel capsules while in UP-LVG capsules it averaged 18 ± 8 days (range 3-39 days). The surface of recovered capsules showed less capsules free of overgrowth in Manugel with respect to UP-LVG alginate. These data were comparable with those observed in empty microcapsules similarly implanted, indicating that the capsular overgrowth was not promoted by the presence of xenogenic islet tissue. In recovered Manugel capsules the percentage of capsules without fibrotic overgrowth was higher than that observed without CyA. The same observation was made in empty capsules. These observations indicate that a combination of a highly purified alginate and short-term immunosuppression prolong islet function in a model of xenotransplantation.

Original languageEnglish
Pages (from-to)221-227
Number of pages7
JournalActa Biomaterialia
Volume2
Issue number2
DOIs
Publication statusPublished - Mar 2006

Keywords

  • Alginate
  • Cell overgrowth
  • Immunosuppression
  • Microcapsules
  • Pancreatic islets

ASJC Scopus subject areas

  • Biomaterials
  • Biomedical Engineering
  • Biotechnology
  • Biochemistry
  • Molecular Biology

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