The long-term clinical success of autologous vein and synthetic vascular grafts 
are limited because of the development of anastomotic intimal hyperplasia (IH). 
We have previously published data suggesting that cyclosporine (CyA) may reduce 
the development of IH in a canine model (Hirko et al., J Vasc Surg 
1993;17:877-887). However, systemic administration of CyA could create serious 
adverse effects. Therefore, it is our long-term goal to test the hypothesis that 
the controlled local release of CyA from a polymeric vascular wrap would prevent 
the development of IH. To test this hypothesis, we developed a controlled 
release polymeric ring that could be placed around anastomotic sites to deliver 
therapeutic drugs locally. The ring is a composite polymeric device consisting 
of poly(DL-lactide-co-glycolide) (PLGA) microspheres embedded in a poly(ethylene 
glycol) hydrogel. Several in vitro studies were conducted to evaluate the 
effects of different sterilization procedures on the properties of the device. 
It was determined that gamma sterilization was the preferred sterilization 
method of choice for this device. In vivo studies were conducted on a swine 
model to evaluate the biocompatibility of the ring. The histological findings of 
the ring implants at 2 and 4 weeks demonstrate the biocompatibility of this 
device.