Figure 2

Circulating pEF-hAAT-derived hAAT protects islet allografts from acute rejection. Healthy heterozygote hAAT transgenic mice were either non-HD tail-vein-injected animals (CT, n = 20) or administered PBS (n = 11), pEF-hAAT (n = 11) or a truncated modified plasmid pEF-Δ-hAAT (n = 6) via HD tail-vein injection, rendered diabetic by a single streptozotocin (STZ) injection and then grafted with allogeneic islets. (A) Representative follow-up of blood glucose and circulating hAAT levels. pEF-hAAT, pEF-Δ-hAAT and PBS administration (indicated by HD injection arrowhead (▼)) was followed by STZ injection (indicated by STZ arrowhead (▼)) before transplantation of allogeneic islets (day 0, indicated by an up arrow (↑)). hAAT levels are indicated by the black dashed line. Blood glucose levels were assessed periodically in pEF-hAAT (black solid line), pEF-Δ-hAAT (gray dashed line) and PBS (gray solid line) groups. Nephrectomy, removal of the graft-containing kidney. (B) Graft survival curve. The day of islet graft failure is defined as the time after transplantation in which blood glucose levels exceed 300 mg/dL. CT, islet graft recipient mice that were not HD tail-vein injected. (C) Graft histology. Accepted allografts were removed from mice for staining (30–100 d; representative stain of a 72-d graft explant). Graft, islets, noninvasive “cuff” and Treg cells are indicated. Red, insulin staining; blue, DAPI nuclear staining; green, foxp3 Treg cells inside the noninvasive mononuclear “cuff.”