Expandable biodegradable polymeric stents for combined mechanical support and pharmacological or radiation therapy

Abstract

An expandable biodegradable polymeric stent is fabricated with biodegradable polymer fibers (Poly-L-lactic acid, PLLA) in a coil shape that is constructed with both central and external or internal peripheral lobes. It is delivered and expanded using a conventional angioplasty balloon system. The disclosed stent can serve as a temporary scaffold for coronary vessels after PTCA or for peripheral endovascular stenting, or it can provide mechanical palliation for strictures of ductile organs (trachea, esophagus, bile and pancreatic ducts, ureter etc.). The disclosed stent also serves as a unique device for specific local drug delivery. Therapeutic agents (chemical compounds, protein enzyme and DNA sequences) and cells can be loaded into the stent and gradually released to target tissues. Local radiation therapy can also be delivered by a specially adapted stent.

1 - 20 . (canceled)  
   
   
       21 . An implantable vascular stent having a compressed configuration and an expanded configuration, comprising: 
 at least one fiber cord defining a repeating structure orbiting and extending along a central axis of the stent, the repeating structure having a plurality of furled segments formed of a first length of the fiber cord and each connecting the proximal ends of two adjacent cord segments, each cord segment formed of a second length of the fiber cord;    wherein in the compressed configuration, the total length between the distal ends of the two adjacent cord segments is less than the sum of the first length and twice of the second length;    wherein the repeating structure is adapted to inelasticly expand into a substantially helical shape about the central axis in the expanded configuration such that the total length between the distal ends of the two adjacent cord segments is approximately equal to the sum of the first length and twice of the second length.    
   
   
       22 . The implantable vascular stent of  claim 21  wherein the repeating structure is adapted to expand into a substantially helical shape, in part, by the unfurling of the furled segments.  
   
   
       23 . The implantable vascular stent of  claim 22  wherein the fiber cord has an elastic limit such that actuation stress forces exceeding the elastic limit will set the repeating structure in the substantially helical shape following removal of an expanding stress forces.  
   
   
       24 . The implantable vascular stent of  claim 21  wherein the repeating structure is adapted to expand into a substantially helical shape, in part, by the deformation of the cord segments.  
   
   
       25 . The implantable vascular stent of  claim 21  wherein the repeating structure is adapted to be expanded by a removably insertable inflatable membrane.  
   
   
       26 . The implantable vascular stent of  claim 21  wherein the repeating structure is adapted to be expanded by the body heat of a host.  
   
   
       27 . The implantable vascular stent of  claim 21 , further comprising a series of longitudinal rods extending along the repeating structure parallel to the central axis and attached to one or more of the cord segments.  
   
   
       28 . The implantable vascular stent of  claim 21  wherein the furled segments extend inward from the repeating structure toward the central axis of the stent.  
   
   
       29 . The implantable vascular stent of  claim 21  wherein the furled segments extend outward away from the central axis of the stent  
   
   
       30 . The implantable vascular stent of  claim 21  wherein the fiber cord is biodegradable within a host.  
   
   
       31 . The implantable vascular stent of  claim 21  wherein the fiber cord is adapted to provide medication to an implant site of the stent.  
   
   
       32 . The implantable vascular stent of  claim 21  wherein the fiber cord comprises a polymer fiber.  
   
   
       33 . An implantable vascular stent having a compressed configuration and an expanded configuration, comprising: 
 at least one fiber cord defining a repeating structure orbiting and extending along a central axis of the stent, the repeating structure having a plurality of furled segments formed of a first length of the fiber cord and each connecting the proximal ends of two adjacent cord segments, cord segment formed of a second length of the fiber cord;    wherein in the compressed configuration, the total length between the distal ends of the two adjacent cord segments is less than the sum of the first length and twice of the second length;    wherein the repeating structure is adapted to be substantially irreversibly expanded into a substantially helical shape about the central axis in the expanded configuration such that the total length between the distal ends of the two adjacent cord segments is approximately equal to the sum of the first length and twice of the second length.    
   
   
       34 . An implantable vascular stent having a compressed configuration and an expanded configuration, comprising: 
 at least one fiber cord defining a repeating structure orbiting and extending along a central axis of the stent, the repeating structure having at least one furled segment formed of a first of the fiber cord and connecting the proximal ends of two adjacent cord segments, each cord segment formed of a second length of the fiber cord;    wherein in the compressed configuration, the total length between the distal ends of the two adjacent cord segments is less than the sum of the first length and twice of the second length;    wherein the repeating structure is adapted to inelasticly expand into a substantially helical shape about the central axis in the expanded configuration such that the total length between the distal ends of the two adjacent cord segments is approximately to the sum of the first length and twice of the second length.