Vascular prosthesis and method for production thereof

• US 20040054406A1
• Filed: 06/18/2003
• Published: 03/18/2004
• Est. Priority Date: 12/19/2000
• Status: Active Grant

• Current Assignee: Nicast Ltd.
• Original Assignee: Nicast Ltd.
• Inventors: Bar, Eli, Dubson, Alexander
• Granted Patent: US 7,115,220 B2
• Time in Patent Office: Days
• US Class Current: 623/1.39
• CPC Class Codes: A61F 2/06 Blood vessels
• CPC Class Codes: A61F 2/07 Stent-grafts
• CPC Class Codes: A61F 2/82 Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents stent-grafts for tubular structures of the body other than blood vessels A61F2/04; stent-grafts for blood vessels A61F2/07; instruments specially adapted for placement or removal of stents or stent-grafts A61F2/95; for closing wounds, or holding wounds closed A61B17/04 - A61B17/115; dilators A61M29/00
• CPC Class Codes: A61F 2/91 made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes
• CPC Class Codes: A61F 2002/072 Encapsulated stents, e.g. wire or whole stent embedded in lining
• CPC Class Codes: A61F 2210/0076 multilayered, e.g. laminated structures
• CPC Class Codes: A61F 2250/0023 differing in porosity
• CPC Class Codes: A61F 2250/0067 Means for introducing or releasing pharmaceutical products into the body
• CPC Class Codes: A61L 27/507 for artificial blood vessels apparatus for applying cells on a blood vessel prosthesis A61F2/062
• CPC Class Codes: A61L 27/56 Porous materials, e.g. foams or sponges
• CPC Class Codes: B29C 67/20 for porous or cellular articles, e.g. of foam plastics, coarse-pored chemical aspects of working up macro-molecular substances to porous or cellular articles C08J9/00
• CPC Class Codes: D01D 5/0007 Electro-spinning non-woven fabrics produced by electro-spinning D04H1/728
• CPC Class Codes: D01D 5/0069 characterised by the spinning section, e.g. capillary tube, protrusion or pin
• CPC Class Codes: D01D 5/0092 characterised by the electrical field, e.g. combined with a magnetic fields, using biased or alternating fields
• CPC Class Codes: D01D 5/18 by means of rotating spinnerets
• CPC Class Codes: D04H 1/728 by electro-spinning electro-spinning methods and apparatus D01D5/0007
• CPC Class Codes: D04H 3/07 otherwise than in a plane, e.g. in a tubular way
• CPC Class Codes: D04H 3/16 with bonds between thermoplastic filaments produced in association with filament formation, e.g. immediately following extrusion
• CPC Class Codes: Y10T 428/13 Hollow or container type article [e.g., tube, vase, etc.]
• CPC Class Codes: Y10T 428/1372 Randomly noninterengaged or randomly contacting fibers, filaments, particles, or flakes
• CPC Class Codes: Y10T 428/139 : Open-ended, self-supporting conduit, cylinder, or tube-type article
• CPC Class Codes: Y10T 428/1393 : Multilayer [continuous layer]
• CPC Class Codes: Y10T 442/614 : Strand or fiber material specified as having microdimensions [i.e., microfiber]

Abstract

A vascular prosthesis comprising a first layer having a predetermined first porosity and a second layer having a predetermined second porosity, wherein the first layer and the second layer are each made of first and second electrospun polymer fibers.

Claims

1. A vascular prosthesis comprising a first layer having a predetermined first porosity and a second layer having a predetermined second porosity, wherein said first layer and said second layer are each made of first and second electrospun polymer fibers.

2. The vascular prosthesis of claim 1, wherein said first and second electrospun polymer fibers are made from the same polymer.

3. The vascular prosthesis of claim 1, wherein said first and second electrospun polymer fibers are made from different polymer.

4. The vascular prosthesis of claim 1, wherein said first layer is an inner layer and said second layer is an outer layer.

5. The vascular prosthesis of claim 1, wherein each of said first layer and said second layer is independently of a tubular structure.

6. The vascular prosthesis of claim 1, further comprising at least one intermediate layer interposed between said first layer and said second layer.

7. The vascular prosthesis of claim 6, wherein said at least one intermediate layer comprises at least one coiled pattern.

8. The vascular prosthesis of claim 7, wherein said coiled pattern is formed from a wound filament.

9. The vascular prosthesis of claim 7, wherein said coiled pattern is embodied within said first layer.

10. The vascular prosthesis of claim 7, wherein said coiled pattern is embodied within said second layer.

11. The vascular prosthesis of claim 7, wherein said wound filament is selected from the group consisting of a wound polypropylene filament and a wound polyurethane filament.

12. The vascular prosthesis of claim 7, wherein said wound filament is coated by a polyurethane solution.

13. The vascular prosthesis of claim 8, wherein said wound filament has a cross-section selected from the group consisting of a circular cross section, an ellipsoid cross section a polygonal cross section and an irregular pattern cross section.

14. The vascular prosthesis of claim 7, wherein said at least one intermediate layer includes a plurality of adhesion sublayers, alternately interposed between said first layer and said coiled pattern, between said coiled pattern and said second layer, and between two congruent coiled patterns.

15. The vascular prosthesis of claim 14, wherein said adhesion sublayers are impervious adhesion sublayers.

16. The vascular prosthesis of claim 14, wherein said adhesion sublayers are formed from electrospun polymer fibers.

17. The vascular prosthesis of claim 6, wherein said at least one intermediate layer has a predetermined porosity.

18. The vascular prosthesis of claim 17, wherein said at least one intermediate layer is made of third electrospun polymer fibers.

19. The vascular prosthesis of claim 1, wherein said first and said second electrospun polymer fibers are biocompatible.

20. The vascular prosthesis of claim 18, wherein said first, said second and said third electrospun polymer fibers are each independently biocompatible.

21. The vascular prosthesis of claim 18, wherein each of said first, said second and said third electrospun polymer fibers are independently selected from the group consisting of polyethylene terephtalat fibers and polyurethane fibers.

22. The vascular prosthesis of claim 1, wherein said first and said second electrospun polymer fibers are selected from the group consisting of polyethylene terephtalat fibers and polyurethane fibers.

23. The vascular prosthesis of claim 1, wherein each of said first layer and said second layer independently includes at least one drug incorporated therein, for delivery of said at least one drug into a body vasculature during or after implantation of the vascular prosthesis within said body vasculature.

24. The vascular prosthesis of claim 23, wherein said first polymer fibers are a combination of a biodegradable polymer and a biostable polymer.

25. The vascular prosthesis of claim 18, wherein said at least one intermediate layer includes at least one drug incorporated therein for delivery of said at least one drug into a body vasculature during or after implantation of the vascular prosthesis within said body vasculature.

26. The vascular prosthesis of claim 23, wherein said second polymer fibers are a combination of a biodegradable polymer and a biostable polymer.

27. The vascular prosthesis of claim 19, having at least one characteristic selected from the group consisting of:

(a) having an inner diameter expandable by at least 10% under a pulsatile pressure characterizing a mammalian blood system;

(b) capable of maintaining said inner diameter while bent at a bent diameter of twice said inner diameter;

(c) having a porosity of at least 60%;

(d) preventing leakage of blood passing therethrough;

(e) characterized by tissue ingrowth and cell endothelization over at least 90% of the vascular prosthesis within at least 10 days from implantation in a mammal; and

(f) having a self-sealing properties so as to minimize blood leakage following piercing.

28. The vascular prosthesis of claim 27, wherein at least a portion of said first, said second and said third electrospun polymer fibers is a combination of a biodegradable polymer and a biostable polymer.

30. The method of claim 1, wherein said precipitation electrode is a rotating mandrel.

49. The method of claim 30, further comprising heating said mandrel prior to, during or subsequent to said step of electrospinning.

50. The method of claim 49, wherein said heating of said mandrel is selected from the group consisting of external heating and internal heating.

51. The method of claim 50, wherein said external heating is by at least one infrared radiator.

52. The method of claim 50, wherein said at least one infrared radiator is an infrared lamp.

53. The method of claim 50, wherein said internal heating is by a built-in heater.

54. The method of claim 53, wherein said built-in heater is an Ohmic built-in heater.

29. A method of producing a vascular prosthesis, the method comprising:

electrospinning a first liquefied polymer onto a precipitation electrode hence providing a first layer having a predetermined first porosity; and

electrospinning a second liquefied polymer onto said precipitation electrode hence providing a second layer having a predetermined second porosity.

31. The method of claim 29, further comprising electrospinning at least one additional liquefied polymer onto said precipitation electrode prior to the step of electrospinning the second liquefied polymer, hence providing at least one intermediate layer interposed between said first layer and said second layer.

32. The method of claim 31, wherein each of said electrospinning steps comprising:

(a) charging said liquefied polymer thereby producing a charged liquefied polymer;

(b) subjecting said charged liquefied polymer to a first electric field; and

(c) dispensing said charged liquefied polymers within said first electric field in a direction of said precipitation electrode.

33. The method of claim 32, wherein said first electric field is defined between said precipitation electrode and a dispensing electrode being at a first potential relative to said precipitation electrode.

34. The method of claim 32, further comprising providing a second electric field defined by a subsidiary electrode being at a second potential relative to said precipitation electrode, said second electric field being for modifying said first electric field.

35. The method of claim 34, wherein said subsidiary electrode serves for reducing non-uniformities in said first electric field.

36. The method of claim 34, wherein said subsidiary electrode serves for controlling fiber orientation of said polymer fiber shell generated upon said precipitation electrode.

37. The method of claim 29, wherein said first layer is an inner layer and said second layer is an outer layer.

38. The method of claim 29, wherein each of said first layer and said second layer is independently of a tubular structure.

39. The method of claim 29, further comprising winding a filament around at least one of said first layer and said second layer, hence providing at least one layer which comprises at least one coiled pattern.

40. The method of claim 39, wherein said filament is formed by polymer fiber extruder.

41. The method of claim 40, wherein said polymer filament extruder includes a bath for holding a melted polymer.

42. The method of claim 41, wherein said melted polymer is a biocompatible melted polymer.

43. The method of claim 42, wherein at least a portion of said biocompatible melted polymer includes a melted polyurethane.

44. The method of claim 40, further comprising cooling said filament by airflow upon exiting said polymer fiber extruder.

45. The method of claim 39, wherein said step of winding and at least one of said steps of electrospinning are performed simultaneously.

46. The method of claim 39, further comprising coating said filament by a polyurethane solution prior to said step of winding said filament.

47. The method of claim 46, wherein said coating comprises dipping said filament into said polyurethane solution.

48. The method of claim 39, further comprising heating said filament prior to, during or subsequent to said step of winding said filament.

55. The method of claim 31, further comprising winding a filament around at least one of said at least one intermediate layer, hence providing at least one layer which comprises at least one coiled pattern.

56. The method of claim 39, wherein said filament is selected from the group consisting of a polypropylene filament and a polyurethane filament.

57. The method of claim 55, wherein said filament is selected from the group consisting of a polypropylene filament and a polyurethane filament.

58. The method of claim 39, wherein said filament has a cross-section selected from the group consisting of a circular cross section, an ellipsoid cross section a polygonal cross section and an irregular pattern cross section.

59. The method of claim 55, wherein said filament has a cross-section selected from the group consisting of a circular cross section, an ellipsoid cross section a polygonal cross section and an irregular pattern cross section.

60. The method of claim 39, wherein said at least one intermediate layer includes a plurality of adhesion sublayers, alternately interposed between said first layer and said coiled pattern, between said coiled pattern and said second layer, and between two congruent coiled patterns.

61. The method claim 60, wherein said adhesion sublayers are impervious adhesion sublayers.

62. The method of claim 60, wherein said adhesion sublayers are formed from electrospun polymer fibers.

63. The method of claim 31, wherein said at least one intermediate layer has a predetermined porosity.

64. The method of claim 29, wherein each of said first liquefied polymer and said second liquefied polymer are independently biocompatible.

65. The method of claim 31, wherein each of said first liquefied polymer, said second liquefied polymer and said at least one additional liquefied polymer are independently biocompatible.

66. The method of claim 29, wherein each of said first liquefied polymer and said second liquefied polymer is independently selected from the group consisting of polyethylene terephtalat fibers and polyurethane fibers.

67. The method of claim 31, wherein each of said first liquefied polymer, said second liquefied polymer and said at least one additional liquefied polymer is independently selected from the group consisting of polyethylene terephtalat fibers and polyurethane fibers.

68. The method of claim 29, further comprising incorporating at least one drug within at least one of said first liquefied polymer and said second liquefied polymer, for delivery of said at least one drug into a body vasculature during or after implantation of the vascular prosthesis within said body vasculature.

69. The method of claim 31, further comprising incorporating at least one drug within at least one of said first liquefied polymer, said second liquefied polymer and said at least one additional liquefied polymer, for delivery of said at least one drug into a body vasculature during or after implantation of the vascular prosthesis within said body vasculature.

70. The method of claim 68, wherein each of said first liquefied polymer and said second liquefied polymer are independently a combination of a biodegradable liquefied polymer and a biostable liquefied polymer.

71. The method of claim 69, wherein each of said first liquefied polymer, said second liquefied polymer and said at least one additional liquefied polymer are independently combination of a biodegradable liquefied polymer and a biostable liquefied polymer.

72. A vascular prosthesis made of at least one biocompatible material, the vascular prosthesis having at least two characteristics selected from the group consisting of:

(a) having an inner diameter expandable by at least 10% under a pulsatile pressure characterizing a mammalian blood system;

(b) capable of maintaining said inner diameter while bent at a bent diameter of twice said inner diameter;

(c) having a porosity of at least 60%;

(d) preventing leakage of blood passing therethrough;

(e) characterized by tissue ingrowth and cell endothelization endothelization over at least 90% of the vascular prosthesis within at least 10 days from implantation in a mammal; and

(f) having a self-sealing properties so as to minimize blood leakage following piercing.

73. The vascular prosthesis of claim 72, wherein at least a portion of the at least one biocompatible material is a biodegradable material.

74. The vascular prosthesis of claim 72, wherein at least a portion of the at least one biocompatible material is a biostable material.

136. The method of claim 72, wherein said pair of blood vessel is selected from the group consisting of a peripheral blood vessel, a vein and a coronary artery.

75. A method of replacing a portion of a blood vessel, comprising:

providing a vascular prosthesis which comprises a first layer having a predetermined first porosity and a second layer having a predetermined second porosity, wherein said first layer and said second layer are each made of first electrospun polymer fibers;

excising the portion of the blood vessel, thereby creating a pair of blood vessel ends; and

connecting said vascular prosthesis to said pair of blood vessel ends so as to allow blood flow through said vascular prosthesis.

76. The method of claim 75, wherein said blood vessel is selected from the group consisting of a peripheral blood vessel, a vein and a coronary artery.

77. The method of claim 75, wherein said vascular prosthesis comprises a first layer having a predetermined first porosity and a second layer having a predetermined second porosity, wherein said first layer and said second layer are each made of first electrospun polymer fibers.

78. The method of claim 77, wherein said first and second electrospun polymer fibers are made from the same polymer.

79. The method of claim 77, wherein said first and second electrospun polymer fibers are made from different polymers.

80. The method of claim 77, wherein said first layer is an inner layer and said second layer is an outer layer.

81. The method of claim 77, wherein each of said first layer and said second layer is independently of a tubular structure.

82. The method of claim 77, further comprising at least one intermediate layer interposed between said first layer and said second layer.

83. The method of claim 82, wherein said at least one intermediate layer comprises at least one coiled pattern.

84. The method of claim 83, wherein said coiled pattern is formed from a wound filament.

85. The method of claim 83, wherein said coiled pattern is embodied within said first layer.

86. The method of claim 83, wherein said coiled pattern is embodied within said second layer.

87. The method of claim 83, wherein said wound filament is selected from the group consisting of a wound polypropylene filament and a wound polyurethane filament.

88. The method of claim 83, wherein said wound filament is coated by a polyurethane solution.

89. The method of claim 84, wherein said wound filament has a cross-section selected from the group consisting of a circular cross section, an ellipsoid cross section a polygonal cross section and an irregular pattern cross section.

90. The method of claim 83, wherein said at least one intermediate layer includes a plurality of adhesion sublayers, alternately interposed between said first layer and said coiled pattern, between said coiled pattern and said second layer, and between two congruent coiled patterns.

91. The method of claim 90, wherein said adhesion sublayers are impervious adhesion sublayers.

92. The method of claim 90, wherein said adhesion sublayers are formed from electrospun polymer fibers.

93. The method of claim 82, wherein said at least one intermediate layer has a predetermined porosity.

94. The method of claim 93, wherein said at least one intermediate layer is made of third electrospun polymer fibers.

95. The method of claim 77, wherein said first and said second electrospun polymer fibers are biocompatible.

96. The method of claim 94, wherein said first, said second and said third electrospun polymer fibers are each independently biocompatible.

97. The method of claim 94, wherein each of said first, said second and said third electrospun polymer fibers are independently selected from the group consisting of polyethylene terephtalat fibers and polyurethane fibers.

98. The method of claim 77, wherein said first and said second electrospun polymer fibers are selected from the group consisting of polyethylene terephtalat fibers and polyurethane fibers.

99. The method of claim 77, wherein each of said first layer and said second layer independently includes at least one drug incorporated therein, for delivery of said at least one drug into a body vasculature during or after implantation of the vascular prosthesis within said body vasculature.

100. The method of claim 99, wherein said first polymer fibers are a combination of a biodegradable polymer and a biostable polymer.

101. The method of claim 94, wherein said at least one intermediate layer includes at least one drug incorporated therein for delivery of said at least one drug into a body vasculature during or after implantation of the vascular prosthesis within said body vasculature.

102. The method of claim 99, wherein said second polymer fibers are a combination of a biodegradable polymer and a biostable polymer.

103. The vascular prosthesis of claim 95, having at least one characteristic selected from the group consisting of:

(a) having an inner diameter expandable by at least 10% under a pulsatile pressure characterizing a mammalian blood system;

(b) capable of maintaining said inner diameter while bent at a bent diameter of twice said inner diameter;

(c) having a porosity of at least 60%;

(d) preventing leakage of blood passing therethrough;

(e) characterized by tissue ingrowth and cell endothelization over at least 90% of the vascular prosthesis within at least 10 days from implantation in a mammal; and

(f) having a self-sealing properties so as to minimize blood leakage following piercing.

104. The method of claim 103, wherein at least a portion of said first, said second and said third electrospun polymer fibers is a combination of a biodegradable polymer and a biostable polymer.

105. A method of bypassing an obstructed portion of a blood vessel, comprising:

providing a vascular prosthesis which comprises a first layer having a predetermined first porosity and a second layer having a predetermined second porosity, wherein said first layer and said second layer are each made of first electrospun polymer fibers;

forming a pair of holes in the blood vessel upstream and downstream the obstruction; and

connecting said vascular prosthesis to said pair of holes so as to allow blood flow through said vascular prosthesis.

106. The method of claim 105, wherein said blood vessel is selected from the group consisting of a peripheral blood vessel, a vein and a coronary artery.

107. The method of claim 105, wherein said vascular prosthesis comprises a first layer having a predetermined first porosity and a second layer having a predetermined second porosity, wherein said first layer and said second layer are each made of first electrospun polymer fibers.

108. The method of claim 107, wherein said first and second electrospun polymer fibers are made from the same polymer.

109. The method of claim 107, wherein said first and second electrospun polymer fibers are made from different polymers.

110. The method of claim 107, wherein said first layer is an inner layer and said second layer is an outer layer.

111. The method of claim 107, wherein each of said first layer and said second layer is independently of a tubular structure.

112. The method of claim 107, further comprising at least one intermediate layer interposed between said first layer and said second layer.

113. The method of claim 112, wherein said at least one intermediate layer comprises at least one coiled pattern.

114. The method of claim 113, wherein said coiled pattern is formed from a wound filament.

115. The method of claim 113, wherein said coiled pattern is embodied within said first layer.

116. The method of claim 113, wherein said coiled pattern is embodied within said second layer.

117. The method of claim 113, wherein said wound filament is selected from the group consisting of a wound polypropylene filament and a wound polyurethane filament.

118. The method of claim 113, wherein said wound filament is coated by a polyurethane solution.

119. The method of claim 114, wherein said wound filament has a cross-section selected from the group consisting of a circular cross section, an ellipsoid cross section a polygonal cross section and an irregular pattern cross section.

120. The method of claim 113, wherein said at least one intermediate layer includes a plurality of adhesion sublayers, alternately interposed between said first layer and said coiled pattern, between said coiled pattern and said second layer, and between two congruent coiled patterns.

121. The method of claim 120, wherein said adhesion sublayers are impervious adhesion sublayers.

122. The method of claim 120, wherein said adhesion sublayers are formed from electrospun polymer fibers.

123. The method of claim 112, wherein said at least one intermediate layer has a predetermined porosity.

124. The method of claim 123, wherein said at least one intermediate layer is made of third electrospun polymer fibers.

125. The method of claim 107, wherein said first and said second electrospun polymer fibers are biocompatible.

126. The method of claim 124, wherein said first, said second and said third electrospun polymer fibers are each independently biocompatible.

127. The method of claim 124, wherein each of said first, said second and said third electrospun polymer fibers are independently selected from the group consisting of polyethylene terephtalat fibers and polyurethane fibers.

128. The method of claim 107, wherein said first and said second electrospun polymer fibers are selected from the group consisting of polyethylene terephtalat fibers and polyurethane fibers.

129. The method of claim 107, wherein each of said first layer and said second layer independently includes at least one drug incorporated therein, for delivery of said at least one drug into a body vasculature during or after implantation of the vascular prosthesis within said body vasculature.

130. The method of claim 129, wherein said first polymer fibers are a combination of a biodegradable polymer and a biostable polymer.

131. The method of claim 124, wherein said at least one intermediate layer includes at least one drug incorporated therein for delivery of said at least one drug into a body vasculature during or after implantation of the vascular prosthesis within said body vasculature.

132. The method of claim 129, wherein said second polymer fibers are a combination of a biodegradable polymer and a biostable polymer.

133. The vascular prosthesis of claim 125, having at least one characteristic selected from the group consisting of:

(a) having an inner diameter expandable by at least 10% under a pulsatile pressure characterizing a mammalian blood system;

(b) capable of maintaining said inner diameter while bent at a bent diameter of twice said inner diameter;

(c) having a porosity of at least 60%;

(d) preventing leakage of blood passing therethrough;

(e) characterized by tissue ingrowth and cell endothelization over at least 90% of the vascular prosthesis within at least 10 days from implantation in a mammal; and

(f) having a self-sealing properties so as to minimize blood leakage following piercing.

134. The method of claim 133, wherein at least a portion of said first, said second and said third electrospun polymer fibers is a combination of a biodegradable polymer and a biostable polymer.

135. A method of connecting a pair of blood vessels, comprising:

providing a vascular prosthesis which comprises a first layer having a predetermined first porosity and a second layer having a predetermined second porosity, wherein said first layer and said second layer are each made of first electrospun polymer fibers;

forming a pair of holes in the pair of blood vessels; and

connecting said vascular prosthesis to said pair of holes so as to allow blood flow through said vascular prosthesis, thereby connecting the pair of blood vessels.

137. The method of claim 135, wherein said vascular prosthesis comprises a first layer having a predetermined first porosity and a second layer having a predetermined second porosity, wherein said first layer and said second layer are each made of first electrospun polymer fibers.

138. The method of claim 137, wherein said first and second electrospun polymer fibers are made from the same polymer.

139. The method of claim 137, wherein said first and second electrospun polymer fibers are made from different polymers.

140. The method of claim 137, wherein said first layer is an inner layer and said second layer is an outer layer.

141. The method of claim 137, wherein each of said first layer and said second layer is independently of a tubular structure.

142. The method of claim 137, further comprising at least one intermediate layer interposed between said first layer and said second layer.

143. The method of claim 142, wherein said at least one intermediate layer comprises at least one coiled pattern.

144. The method of claim 143, wherein said coiled pattern is formed from a wound filament.

145. The method of claim 143, wherein said coiled pattern is embodied within said first layer.

146. The method of claim 143, wherein said coiled pattern is embodied within said second layer.

147. The method of claim 143, wherein said wound filament is selected from the group consisting of a wound polypropylene filament and a wound polyurethane filament.

148. The method of claim 143, wherein said wound filament is coated by a polyurethane solution.

149. The method of claim 144, wherein said wound filament has a cross-section selected from the group consisting of a circular cross section, an ellipsoid cross section a polygonal cross section and an irregular pattern cross section.

150. The method of claim 143, wherein said at least one intermediate layer includes a plurality of adhesion sublayers, alternately interposed between said first layer and said coiled pattern, between said coiled pattern and said second layer, and between two congruent coiled patterns.

151. The method of claim 150, wherein said adhesion sublayers are impervious adhesion sublayers.

152. The method of claim 150, wherein said adhesion sublayers are formed from electrospun polymer fibers.

153. The method of claim 142, wherein said at least one intermediate layer has a predetermined porosity.

154. The method of claim 153, wherein said at least one intermediate layer is made of third electrospun polymer fibers.

155. The method of claim 137, wherein said first and said second electrospun polymer fibers are biocompatible.

156. The method of claim 154, wherein said first, said second and said third electrospun polymer fibers are each independently biocompatible.

157. The method of claim 154, wherein each of said first, said second and said third electrospun polymer fibers are independently selected from the group consisting of polyethylene terephtalat fibers and polyurethane fibers.

158. The method of claim 137, wherein said first and said second electrospun polymer fibers are selected from the group consisting of polyethylene terephtalat fibers and polyurethane fibers.

159. The method of claim 137, wherein each of said first layer and said second layer independently includes at least one drug incorporated therein, for delivery of said at least one drug into a body vasculature during or after implantation of the vascular prosthesis within said body vasculature.

160. The method of claim 159, wherein said first polymer fibers are a combination of a biodegradable polymer and a biostable polymer.

161. The method of claim 154, wherein said at least one intermediate layer includes at least one drug incorporated therein for delivery of said at least one drug into a body vasculature during or after implantation of the vascular prosthesis within said body vasculature.

162. The method of claim 159, wherein said second polymer fibers are a combination of a biodegradable polymer and a biostable polymer.

163. The vascular prosthesis of claim 155, having at least one characteristic selected from the group consisting of:

(a) having an inner diameter expandable by at least 10% under a pulsatile pressure characterizing a mammalian blood system;

(b) capable of maintaining said inner diameter while bent at a bent diameter of twice said inner diameter;

(c) having a porosity of at least 60%;

(d) preventing leakage of blood passing therethrough;

(e) characterized by tissue ingrowth and cell endothelization over at least 90% of the vascular prosthesis within at least 10 days from implantation in a mammal; and

(f) having a self-sealing properties so as to minimize blood leakage following piercing.

164. The method of claim 163, wherein at least a portion of said first, said second and said third electrospun polymer fibers is a combination of a biodegradable polymer and a biostable polymer.