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Transplantation. 2015 Jul;99(7):1341-8. doi: 10.1097/TP.0000000000000661.

Immunoprotection and Functional Improvement of Allogeneic Islets in Diabetic Mice, Using a Stable Indoleamine 2,3-Dioxygenase Producing Scaffold.

Author information

1
Department of Surgery, University of British Columbia, Vancouver, BC, Canada.

Abstract

BACKGROUND:

We have previously shown that an immunomodulatory enzyme, indoleamine 2,3-dioxygenase (IDO) in dermal fibroblasts generates a tryptophan-deficient environment that selectively inhibits proliferation and induces apoptosis of bystander CD4+ and CD8+ T cells, but not pancreatic islets. Because these immune cells are involved in islet allograft rejection, we hypothesized that transplantation of islets embedded in a novel 3-dimensional composite scaffold within which stable IDO-expressing fibroblasts serve as source of local immunosuppression would lead to normoglycemia in a streptozotocin-induced diabetic mouse model.

METHODS:

Islet grafts were prepared by embedding stable IDO-expressing fibroblasts and allogeneic islets into a protease-resistant composite scaffold. Islets function and survival were evaluated in vitro using immunohistochemistry. Allografts were transplanted under the kidney capsule of streptozotocin-induced diabetic mice; viability, function, and criteria for graft take were evaluated. Flow cytometry was performed to determine specific intragraft, draining lymph nodes and spleen T-cell population, and splenocytes alloantigen responsiveness of graft recipients.

RESULTS:

The results of a series of in vitro experiments revealed that IDO-expressing fibroblasts do not compromise islet function or survival. The expression of IDO suppressed the proliferation of alloantigen-stimulated splenocytes. The in vivo experiments revealed that local IDO expression delivered by lentiviral vector prolonged islet allograft survival (51.0 ± 2.9 days) by increasing the population of FOXP3+ regulatory T cells at the graft site and graft-draining lymph nodes and preventing T-cell infiltration.

CONCLUSIONS:

This study shows that incorporation of islets within our novel matrix that is equipped with stable IDO-expressing fibroblasts prolongs allograft survival.

PMID:
25769070
DOI:
10.1097/TP.0000000000000661
[Indexed for MEDLINE]

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