a polylumenal implantable device comprises a body defining a plurality of capillary lumina . the prosthetic device is suitable for implantation in a patient as an arterial or venous bypass graft or shunt , or intra - organ implant as well as other purposes . the improved prosthetic device has increased surface area and preferably a three - dimensional porosity for encouraging the harboring of , for example , endothelial cells , as well as for receiving organized deposition of material such as genetically enhanced cell types . a method for providing a bioactive material to a patient includes the steps of providing a polyluminal implantable organ comprising an implantable body defining a plurality of capillary lumina , treating the interior surfaces of the lumina with a bioactive material or plasma polymerization , and implanting the prosthetic device in the patient so that bodily fluids of the patient come into contact with the treated interior surfaces .