Background. We designed an antisense phosphorothioate oligodeoxynucleotide (oligo) to specifically inhibit the expression of rat intercellular adhesion molecule-1 (ICAM-1) mRNA (IP-9125). Methods. IP-9125 oligo was delivered intravenously by osmotic pump alone or in combination with cyclosporine (CsA) to recipients in order to prevent the rejection of kidney or heart allografts. In additional experiments, kidney allografts were perfused with IP-9125 before grafting. Results. IP-9125 inhibited ICAM-1 mRNA and ICAM-1 protein expression in rat aortic endothelial cells; scrambled controls IP-12140 and IP-13944 were ineffective. Untreated ACI (RT1(a)) recipients rejected Lewis (RT11) kidney allografts at a mean survival time of 8.5±1.1 days. A 14-day intravenous administration of 2.5 mg/kg/day IP- 9125 prolonged the survival of kidney allografts to 39.2±16.4 days; 5.0 mg/kg/day, to 43.0±17.5 days; and 10.0 mg/kg/day, to 50.4±21.6 days. In contrast, a scrambled control IP-12140 was not effective. A combination of 10 mg/kg/day IP-9125 and 1.0 mg/kg/day CsA delivered for 14 days synergistically extended kidney allograft survival times 88.5±7.5 days. In contrast, the combination of 10.0 mg/kg/day control IP-12140 with CsA was ineffective (20.7±3.2 days) when compared with CsA alone (20.2±4.0 days). Similar results were obtained for heart transplants in recipients treated with IP- 9125 alone or in combination with CsA. Furthermore, in situ immunostaining showed that IP-9125 significantly reduced the expression of ICAM-1 protein in kidney allografts. Finally, perfusion of kidney grafts alone with 20.0 mg per 2 ml of IP-9125 protected kidney allografts from rejection (37.5±7.5 days; P<0.001), whereas perfusion with 20 mg per 2 ml of control IP-12140 was ineffective (12.6±5.0 days). Conclusions. Rat ICAM-1 IP-9125 oligo inhibits ICAM-1 protein expression in vitro and in vivo as well as blocks allograft rejection when used for pretreatment of donors, graft perfusion, or postoperative treatment of recipients.
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