Lentivectors encoding immunosuppressive proteins genetically engineer pancreatic β-cells to correct diabetes in allogeneic mice

The effectiveness of genetic engineering with lentivectors to protect transplanted cells from allogeneic rejection was examined using, as a model, type 1 diabetes treatment with β-cell transplantation, whose widespread use has been limited by the requirement for sustained immunosuppressive treatment to prevent graft rejection. We examined whether lentivectors expressing select immunosuppressive proteins encoded by the adenoviral genome early region 3 (AdE3) would protect transplanted β-cells from an alloimmune attack. The insulin-producing β-cell line βTC-tet (C3HeB/FeJ-derived) was transduced with lentiviruses encoding the AdE3 proteins gp19K and RIDα/β. The efficiency of lentiviral transduction of βTC-tet cells exceeded 85%. Lentivector expression of gp19K decreased surface class I major histocompatibility complex expression by over 90%, whereas RIDα/β expression inhibited cytokine-induced Fas upregulation by over 75%. βTC-tet cells transduced with gp19K and RIDα/β lentivectors, but not with a control lentivector, provided prolonged correction of hyperglycemia after transplantation into diabetic BALB/c severe combined immunodeficient mice reconstituted with allogeneic immune effector cells or into diabetic allogeneic BALB/c mice. Thus, genetic engineering of β-cells using gp19K- and RIDα/β-expressing lentiviral vectors may provide an alternative that has the potential to eliminate or reduce treatment with the potent immunosuppressive agents necessary at present for prolonged engraftment with transplanted islets.