a stent - graft composite intraluminal prosthesis comprises an elongate radially adjustable tubular stent , defining opposed exterior and luminal stent surfaces and a polymeric stent sheath covering at least the exterior surface thereof . the stent can include a plurality of open spaces extending between the opposed exterior and interior surfaces so as to permit said radial adjustability . the stent has a polymeric material on its exterior surface , its interior surface , in interstitial relationship with the stent or any combination of the above . the polymer is preferably selected from the group of polymeric materials consisting of biological or genetically engineered spider silks , such as those derived from nephila clavipes . the silk includes bioengineered spider silks as well as silk - like polymers manufactured using human proteins and blends of such silks with commonly used polymeric graft materials . if separate sheaths are placed on both the exterior and interior surfaces of the stent , the sheaths are secured to one another through said open spaces , such as by lamination , suturing or adhesion .