Degradable polymeric carrier for the delivery of IL-10 plasmid DNA to prevent autoimmune insulitis of NOD mice

Recently, we have reported that biodegradable poly [alpha-(4-aminobutyl)-L-glycolic acid] (PAGA) can condense and protect plasmid DNA from DNase I. In this study, we investigated whether the systemic administration of pCAGGS mouse IL-10 (mlL-10) expression plasmid complexed with PAGA can reduce the development of insulitis in non-obese diabetic (NOD) mice. PAGA/mlL-10 plasmid complexes were stable for more than 60 min, but the naked DNA was destroyed within 10 min by DNase I. The PAGA/DNA complexes were injected into the tail Vein of 3-week-old NOD mice. Serum mlL-10 level peaked at 5 days after injection, and could be detected for more than 9 weeks. The prevalence of severe insulitis on 12-week-old NOD mice was markedly reduced by the intravenous injection of PAGA/DNA complex (15.7%) compared with that of naked DNA injection (34.5%) and non-treated controls (90.9%). In conclusion, systemic administration of pCAGGS mlL-10 plasmid/PAGA complexes can reduce the severity of insulitis in NOD mice. This study shows that the PAGA/DNA complex has the potential for the prevention of autoimmune diabetes mellitus.