Angiopolarity: a new design parameter for cell transplantation devices and its application to degradable systems.

The purpose of this study was to obtain directional angiogenesis of small blood vessels and capillaries to an implant made from a resorbable polymer for hepatocyte transplantation. It was intended to mimic the native acinar structure of the liver in form to facilitate replication of the cells and organ growth. The implant device structure was designed for injection to minimize surgical trauma. Hollow microspheres with an open porous wall structure and one large central opening were made from poly(d,1-lactic-co-glycolic acid) (85:15 lactic:glycolic). This polymeric scaffold was seeded with hepatocytes and implanted into the abdominal wall muscle of syngeneic Fisher rats. Specimens explanted up to 56 days postoperatively showed hepatocyte survival and the development of a directional blood supply, a phenomenon known as "angiopolarity." This study should help in addressing the issue as to whether vascular cell implants with posttransplantation organ growth should be attempted.