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UBC Theses and Dissertations

Evaluating the therapeutic use of Indoleamine 2,3-dioxygenase (IDO) expressing allogenic dermal fibroblast populated within an acellular skin substitute as a wound coverage Farrokhi, Ali


Acute and chronic wounds contribute to increased morbidity and mortality in affected people and impose significant financial burdens on healthcare systems. Allogeneic cell-based skin substitutes have been proposed as ready-to-use wound coverage as an alternative to conventional split-thickness skin grafts, but the survival and usefulness of such cells after transplantation into an immunocompetent host remain controversial. We hypothesize that the application of an indoleamine 2,3-dioxygenase (IDO) expressing allogenic dermal fibroblast populated within an acellular dermal matrix (ADM) is sufficient to create an immune-privileged area within the wound to protect fibroblasts from rejection. Fibroblasts in the skin substitute can potentially assist the graft to restore its function by synthesizing extracellular matrix components and growth factors. In this study, ADMs were prepared using a novel detergent–free method, recellularized with IDO-expressing or control fibroblasts from C57/B6 mice, and were transplanted on splinted full-thickness skin wounds in Balb/c mice. Transplantation studies demonstrated that ADM significantly enhanced the wound-healing process but there was no demonstrable benefit when the ADM was recellularized with fibroblasts. Investigating the transplanted cells’ fate by bioluminescence in vivo imaging after intra-hypo-dermal injection of fibroblasts in to mouse skin revealed that both type of fibroblasts were rejected in allogeneic recipients while in immunodeficient NOD-SCID-Il2r gamma null (NSG) mice they were not. Allogeneic fibroblasts transplanted in natural killer T cell and gamma delta T (NKT) cell deficient mice were rejected as well. Depleting natural killer (NK) cells or CD4+ T cells could delay the rejection but not prevent it. Double depletion of CD4+ and CD8+ cells could partially prevent the rejection. Analyzing the infiltrated immune cells to graft region in time of cell rejection revealed the presence of high number of monocytes, macrophage and neutrophils. Our data indicate a clear immune response to allogeneic fibroblasts in which both innate and T-cell immune response are involved in targeting cells. Although it has been reported by other researchers that IDO-expressing cells exhibit strong immunosuppressive activity in vitro and in vivo, we documented rejection of these cells in our study, suggesting that the application of these cells in wound sites requires further improvements.

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