High molecular weight polylactide and polycaprolactone copolymer and blends for bioresorbable vascular scaffolds

Abstract

Bioresorbable polymer vascular scaffolds made of combinations of polylactide and polycaprolactone having a high molecular weight polymer, thin struts in a selected range and sufficient radial strength to support a vessel upon deployment. The scaffolds have degradation behavior of molecular weight, radial strength, and mass that are conducive to healing of a vessel including providing patency to a vessel, reduction of radial strength, breaking up, and resorbing to allow return of the vessel to a natural state.

1 . (canceled) 
     
     
         2 . A stent comprising:
 a bioresorbable polymer scaffold comprising a polymer combination including a polylactide polymer and polycaprolactone,   wherein the polymer combination is a random copolymer of poly(L-lactide)(PLLA) and polycaprolactone,   wherein the scaffold includes a plurality of interconnected struts,   wherein the scaffold is made of at least 95 wt % of the polymer combination,   wherein a thickess of the struts is 80 to 100 microns and a width of the struts is 200 to 250 microns, and   wherein the scaffold has a crimped state and a deployed state and a radial strength of the scaffold when expanded from the crimped state to the deployed state in saline or bodily fluid at 37° C. is at least 650 mm Hg.   
     
     
         3 . The stent of  claim 2 , wherein the polymer combination comprises 1 to 5 wt % of caprolactone units. 
     
     
         4 . The stent of  claim 2 , wherein a hoop ultimate tensile strength is at least 25% greater than an axial ultimate tensile strength of the scaffold. 
     
     
         5 . The stent of  claim 2 , wherein a concentration of unreacted lactide monomer in the scaffold is 0.5 to 1 wt %. 
     
     
         7 . The stent of  claim 2 , wherein a number average molecular weight (Mn) of the polymer combination is less than 60 kDa at 1 year of exposure of the scaffold to saline or bodily fluids at 37° C. 
     
     
         8 . The stent of  claim 2 , wherein a crystallinity of the scaffold is 25% to 50%. 
     
     
         9 . The stent of  claim 2 , wherein a change in retardance as measured by polarized light microscopy (PLM) from an inner diameter to 50% of the thickness to the outer diameter of the scaffold is less than 50%. 
     
     
         10 . The stent of  claim 2 , wherein a number average molecular weight (Mn) of a polymer of the polymer combination is greater than 110 kDa. 
     
     
         11 . A stent comprising:
 a bioresorbable polymer scaffold comprising a polymer formulation including a random copolymer of poly(L-lactide) (PLLA) polymer and polycaprolactone (PCL),   wherein the scaffold includes a plurality of interconnected struts,   wherein a thickess of the struts is 80 to 100 microns and a width of the struts is 200 to 250 microns,   wherein a number average molecular weight (Mn) of the blend is greater than 60 kDa, and   wherein the scaffold has a crimped state and a deployed state and a radial strength of the scaffold when expanded from the crimped state to the deployed state in saline or bodily fluid at 37° C. is at least 650 mm Hg.   
     
     
         12 . The stent of  claim 11 , wherein the polymer formulation comprises 1 to 5 wt % of caprolactone units.