Electrospun material covered appliances and methods of manufacture

Abstract

A medical appliance or prosthesis may comprise one or more layers of electrospun nanofibers, including electrospun polymers. The electrospun material may comprise layers including layers of polytetrafluoroethylene (PTFE). Electrospun nanofiber mats of certain porosities may permit tissue ingrowth into or attachment to the prosthesis.

1 . A method for promoting endothelial cell growth on an implantable medical appliance, comprising implanting the medical appliance into a patient, the medical appliance comprising:
 at least one electrospun polymer layer having a percent porosity of between about 35% and about 70%, such that endothelial cells grow on or attach to the surface of the at least one electrospun polymer layer and   a second polymer layer coupled to the at least one electrospun polymer layer the second polymer layer impermeable to tissue growth into the second polymer layer.   
     
     
         2 . The method of  claim 1 , wherein the implantable medical appliance comprises a stent. 
     
     
         3 . The method of  claim 1 , wherein the implantable medical appliance comprises a graft. 
     
     
         4 . The method of  claim 1 , wherein the at least one electrospun polymer layer comprises an electrospun PTFE layer. 
     
     
         5 . The method of  claim 4 , wherein the second polymer layer inhibits fluid migration into or through a wall of the implantable medical appliance. 
     
     
         6 . The method of  claim 5 , wherein the second polymer layer comprises an FEP layer. 
     
     
         7 . The method of  claim 4 , wherein the electrospun PTFE comprises a fiber mat of randomized PTFE microfibers or nanofibers. 
     
     
         8 . The method of  claim 1 , wherein the at least one polymer layer of the implanted medical appliance is configured to permit at least 150% in vitro endothelial cell attachment, compared to an expanded PTFE control material. 
     
     
         9 . The method of  claim 1 , wherein the at least one polymer layer of the implanted medical appliance is configured to permit between 30% and 170% in vitro endothelial cell attachment, compared to an expanded PTFE control material. 
     
     
         10 . The method of  claim 1 , wherein the percent porosity of the electrospun polymer layer is between about 40% and about 60%. 
     
     
         11 . The method of  claim 4 , wherein the electrospun PTFE layer has been heated and stretched after sintering. 
     
     
         12 . A method for promoting cellular growth into an implantable medical appliance, comprising:
 obtaining a medical appliance coated with at least one electrospun polymer layer having a percent porosity of between about 30% and about 80%, and at least one layer that is substantially impervious to cellular growth into the layer; and   implanting the medical appliance into a patient such that the electrospun polymer layer of the medical appliance is in direct contact with body fluid or body tissue.   
     
     
         13 . The method of  claim 12 , wherein the at least one electrospun polymer layer comprises electrospun PTFE material. 
     
     
         14 . The method of  claim 13 , wherein the electrospun PTFE material is configured to permit at least 20% cellular penetration, in vivo two weeks after murine implantation. 
     
     
         15 . (canceled) 
     
     
         16 . (canceled) 
     
     
         17 . The method of  claim 12 , wherein the substantially impervious layer comprises an FEP layer. 
     
     
         18 . The method of  claim 17 , wherein the medical appliance comprises a third polymer layer comprising an electrospun PTFE layer, and wherein the FEP layer is disposed between a first and the third polymer layers. 
     
     
         19 . A method for inhibiting an inflammatory response to an implantable medical appliance, comprising implanting the medical appliance into a patient, the medical appliance coated with a first electrospun polymer layer comprising a porous PTFE mat and a second polymer layer comprising FEP that inhibits tissue ingrowth into the second polymer layer. 
     
     
         20 . The method of  claim 19 , wherein the first electrospun polymer layer, when placed in vivo, has an H-score of less than 150 two weeks after murine implantation. 
     
     
         21 . The method of  claim 19 , wherein the percent porosity of the first electrospun polymer layer is between about 40% and about 60%. 
     
     
         22 . The method of  claim 19 , wherein the first electrospun PTFE layer has been heated and stretched after sintering.