Medicated polymer-coated stent assembly

• US 20040030377A1
• Filed: 06/18/2003
• Published: 02/12/2004
• Est. Priority Date: 10/19/2001
• Status: Abandoned Application

• Current Assignee: Nicast Ltd.
• Original Assignee: Nicast Ltd.
• Inventors: Bar, Eli, Dubson, Alexander
• Application Number:
  US10/433,620
• Publication Number:
  US 20040030377A1
• Time in Patent Office: Days
• US Class Current: 623/1.13
• CPC Class Codes: A61F 2/07 Stent-grafts
• CPC Class Codes: A61F 2/90 characterised by a net-like or mesh-like structure
• 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 2002/075 the stent being loosely attached to the graft material, e.g. by stitching
• CPC Class Codes: A61F 2250/0067 Means for introducing or releasing pharmaceutical products into the body
• CPC Class Codes: A61L 27/56 Porous materials, e.g. foams or sponges
• CPC Class Codes: D01D 5/0084 Coating by electro-spinning, i.e. the electro-spun fibres are not removed from the collecting device but remain integral with it, e.g. coating of prostheses
• CPC Class Codes: D01F 1/10 Other agents for modifying properties
• 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

Abstract

A stent assembly comprising an expensible tubular supporting element and at least one coat of electrospun polymer fibers, each of the at least one coat having a predetermined porosity, the at least one coat including at least one pharmaceutical agent incorporated therein for delivery of the at least one pharmaceutical agent into a body vasculature during or after implantation of the stent assembly within the body vasculature.

Claims

1. A stent assembly comprising an expensible tubular supporting element and at least one coat of electrospun polymer fibers, each of said at least one coat having a predetermined porosity, said at least one coat including at least one pharmaceutical agent incorporated therein for delivery of said at least one pharmaceutical agent into a body vasculature during or after implantation of the stent assembly within said body vasculature.

2. The stent assembly of claim 1, wherein said expensible tubular supporting element is designed and constructed for dilating a constricted blood vessel in said body vasculature.

3. The stent assembly of claim 1, wherein each of said at least one coat is independently a tubular structure.

4. The stent assembly of claim 2, wherein said at least one pharmaceutical agent serves for treating at least one disorder in said blood vessel.

5. The stent assembly of claim 4, wherein said at least one disorder comprises an injury inflicted on tissues of said blood vessel upon implantation of the stent assembly therein.

6. The stent assembly of claim 4, wherein said at least one disorder is selected from the group consisting of restenosis and in-stent stenosis.

7. The stent assembly of claim 4, wherein said at least one disorder is hyper cell proliferation.

8. The stent assembly of claim 1, wherein said at least one coat and said at least one pharmaceutical agent are configured and designed so as to provide a predetermined sustained release rate for effecting said delivery.

9. The stent assembly of claim 1, wherein said at least one coat and said at least one pharmaceutical agent are configured and designed so as to provide a predetermined duration of said delivery.

10. The stent assembly of claim 1, wherein said delivery is by diffusion.

11. The stent assembly of claim 10, wherein said delivery is initiated by a radial stretch of said at least one coat, said radial stretch is caused by an expansion of said expensible tubular supporting element.

12. The stent assembly of claim 1, wherein said expensible tubular supporting element comprises a deformable mesh of metal wires.

13. The stent assembly of claim 1, wherein said expensible tubular supporting element comprises a deformable mesh of stainless steel wires.

14. The stent assembly of claim 1, wherein said at least one coat comprises an inner coat and an outer coat.

15. The stent assembly of claim 14, wherein said inner coat comprises a layer lining an inner surface of said expensible tubular supporting element.

16. The stent assembly of claim 14, wherein said outer coat comprises a layer covering an outer surface of said expansible tubular supporting element.

17. The stent assembly of claim 1, wherein said electrospun polymer fibers are made of a biocompatible polymer.

18. The stent assembly of claim 1, wherein at least a portion of said electrospun polymer fibers is made of a biodegradable polymer.

19. The stent assembly of claim 1, wherein at least a portion of said electrospun polymer fibers is made of a biostable polymer.

20. The stent assembly of claim 1, wherein at least a portion of said electrospun polymer fibers is made of a combination of a biodegradable polymer and a biostable polymer.

21. The stent assembly of claim 1, wherein said electrospun polymer fibers are manufactured from a liquefied polymer.

22. The stent assembly of claim 21, wherein said at least one pharmaceutical agent is dissolved in said liquefied polymer.

23. The stent assembly of claim 21, wherein said at least one pharmaceutical agent is suspended in said liquefied polymer.

24. The stent assembly of claim 1, wherein said at least one pharmaceutical agent is constituted by compact objects distributed between said electrospun polymer fibers of said at least one coat.

25. The stent assembly of claim 24, wherein said compact objects are capsules.

26. The stent assembly of claim 1, wherein said at least one pharmaceutical agent is constituted by particles embedded in said electrospun polymer fibers.

27. The stent assembly of claim 1, wherein said at least one coat includes an adhesion layer.

28. The stent assembly of claim 27, wherein said adhesion layer is impervious adhesion layer.

29. The stent assembly of claim 27, wherein said adhesion layer is formed from electrospun polymer fibers.

30. The stent assembly of claim 1, wherein said electrospun polymer fibers are selected from the group consisting of polyethylene-terephtalat fibers and polyurethane fibers.

31. The stent assembly of claim 1, wherein said at least one pharmaceutical agent comprises heparin or heparin derivative.

32. The stent assembly of claim 1, wherein said at least one pharmaceutical agent comprises a radioactive compound.

33. The stent assembly of claim 1, wherein said at least one pharmaceutical agent comprises silver sulfadiazine.

34. The stent assembly of claim 1, wherein said at least one pharmaceutical agent comprises an antiproliferative drug.

35. The stent assembly of claim 1, wherein said at least one pharmaceutical agent comprises an anticoagulant drug.

36. The stent assembly of claim 12, wherein said at least one coat exposes gaps between said metal wires and exclusively covers said metal wires.

37. The stent assembly of claim 12, wherein said at least one coat substantially covers both gaps between said metal wires and said metal wires.

38. A method of producing a stent assembly, the method comprising:

(a) electrospinning a first liquefied polymer onto an expensible tubular supporting element, thereby coating said tubular supporting element with a first coat having a predetermined porosity; and

(b) incorporating at least one pharmaceutical agent into said first coat.

39. The method of claim 38, wherein said at least one pharmaceutical agent is mixed with said liquefied polymer prior to said step of electrospinning, hence said step of incorporating said at least one pharmaceutical agent into said first coat is concomitant with said electrospinning.

40. The method of claim 39, wherein said at least one pharmaceutical agent is dissolved in said in said liquefied polymer.

41. The method of claim 39, wherein said at least one pharmaceutical agent is suspended in said liquefied polymer.

42. The method of claim 39, wherein said at least one pharmaceutical agent is constituted by particles embedded in polymer fibers produced during said step of electrospinning.

43. The method of claim 38, wherein said step of incorporating at least one pharmaceutical agent into said first coat comprises constituting said at least one pharmaceutical agent into compact objects, and distributing said compact objects between polymer fibers produced during said step of electrospinning.

44. The method of claim 43, wherein said compact objects are capsules.

45. The method of claim 43, wherein said compact objects are in a powder form.

46. The method of claim 43, wherein said distributing of said compact objects is by spraying.

47. The method of claim 38, wherein said expensible tubular supporting element comprises a deformable mesh of metal wires.

48. The method of claim 38, wherein said expensible tubular supporting element comprises a deformable mesh of stainless steel wires.

49. The method of claim 38, wherein said coat is of a tubular structure.

50. The method of claim 38, further comprising mounting said tubular supporting element onto a rotating mandrel, prior to said step (a).

51. The method of claim 50, further comprising electrospinning a second liquefied polymer onto said mandrel, prior to said step (a), hence providing an inner coat.

52. The method of claim 38, further comprising electrospinning at least one additional liquefied polymer onto said first coat, hence providing at least one additional coat.

53. The method of claim 38, further comprising providing at least one adhesion layer onto said tubular supporting element.

54. The method of claim 51, further comprising providing at least one adhesion layer onto at least one coat.

55. The method of claim 53, wherein said adhesion layer is an impervious adhesion layer.

56. The method of claim 54, wherein said adhesion layer is an impervious adhesion layer.

57. The method of claim 53, wherein said providing at least one adhesion layer is by electrospinning.

58. The method of claim 54, wherein said providing at least one adhesion layer is by electrospinning.

59. The method of claim 50, wherein said electrospinning step comprises:

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

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

(iii) dispensing said charged liquefied polymers within said first electric field in a direction of said mandrel.

60. The method of claim 59, wherein said mandrel is of a conductive material.

61. The method of claim 60, wherein said first electric field is defined between said mandrel and a dispensing electrode being at a first potential relative to said mandrel.

62. The method of claim 60, further comprising providing a second electric field defined by a subsidiary electrode being at a second potential relative to said mandrel, said second electric field being for modifying said first electric field.

63. The method of claim 62, wherein said subsidiary electrode serves for reducing non-uniformities in said first electric field.

64. The method of claim 62, wherein said subsidiary electrode serves for controlling fiber orientation of each of said coats.

65. The method of claim 59, wherein said mandrel is of a dielectric material.

66. The method of claim 59, wherein said tubular supporting element serves as a mandrel.

67. The method of claim 65, wherein said first electric field is defined between said tubular supporting element and a dispensing electrode being at a first potential relative to said tubular supporting element.

68. The method of claim 65, further comprising providing a second electric field defined by a subsidiary electrode being at a second potential relative to said tubular supporting element, said second electric field being for modifying said first electric field.

69. The method of claim 68, wherein said subsidiary electrode serves for reducing non-uniformities in said first electric field.

70. The method of claim 68, wherein said subsidiary electrode serves for controlling fiber orientation of each of said coats.

71. The method of claim 38, wherein said first liquefied polymer is a biocompatible liquefied polymer.

72. The method of claim 38, wherein said first liquefied polymer is a biodegradable liquefied polymer.

73. The method of claim 38, wherein said first liquefied polymer is a biostable liquefied polymer.

74. The method of claim 38, wherein first liquefied polymer is a combination of a biodegradable liquefied polymer and a biostable liquefied polymer.

75. The method of claim 51, wherein said second liquefied polymer is a biocompatible liquefied polymer.

76. The method of claim 51, wherein said second liquefied polymer is a biodegradable liquefied polymer.

77. The method of claim 51, wherein said second liquefied polymer is a biostable liquefied polymer.

78. The method of claim 51, wherein said second liquefied polymer is a combination of a biodegradable liquefied polymer and a biostable liquefied polymer.

79. The method of claim 52, wherein each of said at least one additional liquefied polymer is independently a biocompatible liquefied polymer.

80. The method of claim 52, wherein each of said at least one additional liquefied polymer is independently biodegradable liquefied polymer.

81. The method of claim 52, wherein each of said at least one additional liquefied polymer is independently a biostable liquefied polymer.

82. The method of claim 52, wherein each of said at least one additional liquefied polymer is independently a combination of a biodegradable liquefied polymer and a biostable liquefied polymer.

83. The method of claim 38, wherein said at least one pharmaceutical agent is heparin.

84. The method of claim 38, wherein said at least one pharmaceutical agent is a radioactive compound.

85. The method of claim 38, wherein said at least one pharmaceutical agent is silver sulfadiazine.

86. The method of claim 50, further comprising heating said mandrel prior to, during or subsequent to said step of electrospinning.

87. The method of claim 86, wherein said heating of said mandrel is selected from the group consisting of external heating and internal heating.

88. The method of claim 87, wherein said external heating is by at least one infrared radiator.

89. The method of claim 88, wherein said at least one infrared radiator is an infrared lamp.

90. The method of claim 87, wherein said internal heating is by a built-in heater.

91. The method of claim 90, wherein said built-in heater is an Ohmic built-in heater.

92. The method of claim 50, further comprising removing the stent assembly from said mandrel.

93. The method of claim 92, further comprising dipping the stent assembly in a vapor.

94. The method of claim 93, further comprising heating said vapor.

95. The method of claim 92, wherein said vapor is saturated a DMF vapor.

96. The method of claim 38, further comprising exposing the stent assembly to a partial vacuum processing.

97. A method of treating a constricted blood vessel, the method comprising placing a stent assembly in the constricted blood vessel, said stent assembly comprises an expensible tubular supporting element and at least one coat of electrospun polymer fibers, each of said at least one coat having a predetermined porosity, said at least one coat including at least one pharmaceutical agent incorporated therein for delivery of said at least one pharmaceutical agent into a body vasculature during or after implantation of the stent assembly within said body vasculature.

98. The method of claim 97, wherein said expensible tubular supporting element is designed and constructed for dilating a constricted blood vessel in said body vasculature.

99. The method of claim 97, wherein each of said at least one coat is independently a tubular structure.

100. The method of claim 98, wherein said at least one pharmaceutical agent serves for treating at least one disorder in said blood vessel.

101. The method of claim 100, wherein said at least one disorder comprises an injury inflicted on tissues of said blood vessel upon implantation of the stent assembly therein.

102. The method of claim 100, wherein said at least one disorder is selected from the group consisting of restenosis and in-stent stenosis.

103. The method of claim 100, wherein said at least one disorder is hyper cell proliferation.

104. The method of claim 97, wherein said at least one coat and said at least one pharmaceutical agent are configured and designed so as to provide a predetermined sustained release rate for effecting said delivery.

105. The method of claim 97, wherein said at least one coat and said at least one pharmaceutical agent are configured and designed so as to provide a predetermined duration of said delivery.

106. The method of claim 97, wherein said delivery is by diffusion.

107. The method of claim 106, wherein said delivery is initiated by a radial stretch of said at least one coat, said radial stretch is caused by an expansion of said expensible tubular supporting element.

108. The method of claim 97, wherein said expensible tubular supporting element comprises a deformable mesh of metal wires.

109. The method of claim 97, wherein said expensible tubular supporting element comprises a deformable mesh of stainless steel wires.

110. The method of claim 97, wherein said at least one coat comprises an inner coat and an outer coat.

111. The method of claim 110, wherein said inner coat comprises a layer lining an inner surface of said expansible tubular supporting element.

112. The method of claim 110, wherein said outer coat comprises a layer covering an outer surface of said expensible tubular supporting element.

113. The method of claim 97, wherein said electrospun polymer fibers are made of a biocompatible polymer.

114. The method of claim 97, wherein at least a portion of said electrospun polymer fibers is made of a biodegradable polymer.

115. The method of claim 97, wherein at least a portion of said electrospun polymer fibers is made of a biostable polymer.

116. The method of claim 97, wherein at least a portion of said electrospun polymer fibers is made of a combination of a biodegradable polymer and a biostable polymer.

117. The method of claim 97, wherein said electrospun polymer fibers are manufactured from a liquefied polymer.

118. The method of claim 117, wherein said at least one pharmaceutical agent is dissolved in said liquefied polymer.

119. The method of claim 117, wherein said at least one pharmaceutical agent is suspended in said liquefied polymer.

120. The method of claim 97, wherein said at least one pharmaceutical agent is constituted by compact objects distributed between said electrospun polymer fibers of said at least one coat.

121. The method of claim 120, wherein said compact objects are capsules.

122. The method of claim 97, wherein said at least one pharmaceutical agent is constituted by particles embedded in said electrospun polymer fibers.

123. The method of claim 97, wherein said at least one coat includes an adhesion layer.

124. The method of claim 123, wherein said adhesion layer is impervious adhesion layer.

125. The method of claim 123, wherein said adhesion layer is formed from electrospun polymer fibers.

126. The method of claim 97, wherein said electrospun polymer fibers are selected from the group consisting of polyethylene-terephtalat fibers and polyurethane fibers.

127. The method of claim 97, wherein said at least one pharmaceutical agent comprises heparin or heparin derivative.

128. The method of claim 97, wherein said at least one pharmaceutical agent comprises a radioactive compound.

129. The method of claim 97, wherein said at least one pharmaceutical agent comprises silver sulfadiazine.

130. The method of claim 97, wherein said at least one pharmaceutical agent comprises an antiproliferative drug.

131. The method of claim 97, wherein said at least one pharmaceutical agent comprises an anticoagulant drug.

132. The method of claim 108, wherein said at least one coat exposes gaps between said metal wires and exclusively covers said metal wires.

133. The method of claim 108, wherein said at least one coat substantially covers both gaps between said metal wires and said metal wires.

134. A method of dilating a constricted blood vessel, the method comprising:

(a) providing a stent assembly comprises an expensible tubular supporting element and at least one coat of electrospun polymer fibers, each of said at least one coat having a predetermined porosity, said at least one coat including at least one pharmaceutical agent incorporated therein;

(b) placing said stent assembly to a constricted region in the constricted blood vessel; and

(c) radially expanding said stent assembly within the blood vessel so as to dilate said constricted region and to allow blood flow through the blood vessel.

135. The method of claim 134, wherein said expensible tubular supporting element is designed and constructed for dilating a constricted blood vessel in said body vasculature.

136. The method of claim 134, wherein each of said at least one coat is independently a tubular structure.

137. The method of claim 135, wherein said at least one pharmaceutical agent serves for treating at least one disorder in said blood vessel.

138. The method of claim 137, wherein said at least one disorder comprises an injury inflicted on tissues of said blood vessel upon implantation of the stent assembly therein.

139. The method of claim 137, wherein said at least one disorder is selected from the group consisting of restenosis and in-stent stenosis.

140. The method of claim 137, wherein said at least one disorder is hyper cell proliferation.

141. The method of claim 134, wherein said at least one coat and said at least one pharmaceutical agent are configured and designed so as to provide a predetermined sustained release rate for effecting said delivery.

142. The method of claim 134, wherein said at least one coat and said at least one pharmaceutical agent are configured and designed so as to provide a predetermined duration of said delivery.

143. The method of claim 134, wherein said delivery is by diffusion.

144. The method of claim 143, wherein said delivery is initiated by a radial stretch of said at least one coat, said radial stretch is caused by an expansion of said expensible tubular supporting element.

145. The method of claim 134, wherein said expansible tubular supporting element comprises a deformable mesh of metal wires.

146. The method of claim 134, wherein said expensible tubular supporting element comprises a deformable mesh of stainless steel wires.

147. The method of claim 134, wherein said at least one coat comprises an inner coat and an outer coat.

148. The method of claim 147, wherein said inner coat comprises a layer lining an inner surface of said expansible tubular supporting element.

149. The method of claim 147, wherein said outer coat comprises a layer covering an outer surface of said expensible tubular supporting element.

150. The method of claim 134, wherein said electrospun polymer fibers are made of a biocompatible polymer.

151. The method of claim 134, wherein at least a portion of said electrospun polymer fibers is made of a biodegradable polymer.

152. The method of claim 134, wherein at least a portion of said electrospun polymer fibers is made of a biostable polymer.

153. The method of claim 134, wherein at least a portion of said electrospun polymer fibers is made of a combination of a biodegradable polymer and a biostable polymer.

154. The method of claim 134, wherein said electrospun polymer fibers are manufactured from a liquefied polymer.

155. The method of claim 154, wherein said at least one pharmaceutical agent is dissolved in said liquefied polymer.

156. The method of claim 154, wherein said at least one pharmaceutical agent is suspended in said liquefied polymer.

157. The method of claim 134, wherein said at least one pharmaceutical agent is constituted by compact objects distributed between said electrospun polymer fibers of said at least one coat.

158. The method of claim 157, wherein said compact objects are capsules.

159. The method of claim 134, wherein said at least one pharmaceutical agent is constituted by particles embedded in said electrospun polymer fibers.

160. The method of claim 134, wherein said at least one coat includes an adhesion layer.

161. The method of claim 160, wherein said adhesion layer is impervious adhesion layer.

162. The method of claim 160, wherein said adhesion layer is formed from electrospun polymer fibers.

163. The method of claim 134, wherein said electrospun polymer fibers are selected from the group consisting of polyethylene-terephtalat fibers and polyurethane fibers.

164. The method of claim 134, wherein said at least one pharmaceutical agent comprises heparin or heparin derivative.

165. The method of claim 134, wherein said at least one pharmaceutical agent comprises a radioactive compound.

166. The method of claim 134, wherein said at least one pharmaceutical agent comprises silver sulfadiazine.

167. The method of claim 134, wherein said at least one pharmaceutical agent comprises an antiproliferative drug.

168. The method of claim 134, wherein said at least one pharmaceutical agent comprises an anticoagulant drug.

169. The method of claim 145, wherein said at least one coat exposes gaps between said metal wires and exclusively covers said metal wires.

170. The method of claim 145, wherein said at least one coat substantially covers both gaps between said metal wires and said metal wires.

171. A method of coating a medical implant, implantable in a body, and loading the medical implant with a pharmaceutical agent, the method comprising:

(a) electrospinning a first liquefied polymer onto the medical implant, thereby coating the medical implant with a first coat having a predetermined porosity; and

(b) incorporating at least one pharmaceutical agent into said first coat;

thereby providing a coated medical implant loaded with the at least one pharmaceutical agent.

172. The method of claim 171, wherein the medical implant is selected from the group consisting of a graft, a patch and a valve.

173. The method of claim 171, wherein said at least one pharmaceutical agent is mixed with a liquefied polymer prior to said step of electrospinning, hence said step of incorporating said at least one pharmaceutical agent into said first coat is concomitant with said electrospinning.

174. The method of claim 173, wherein said at least one pharmaceutical agent is dissolved in said in said first liquefied polymer.

175. The method of claim 173, wherein said at least one pharmaceutical agent is suspended in said first liquefied polymer.

176. The method of claim 173, wherein said at least one pharmaceutical agent is constituted by particles embedded in polymer fibers produced during said step of electrospinning.

177. The method of claim 171, wherein said step of incorporating at least one pharmaceutical agent into said first coat comprises constituting said at least one pharmaceutical agent into compact objects, and distributing said compact objects between polymer fibers produced during said step of electrospinning.

178. The method of claim 177, wherein said compact objects are capsules.

179. The method of claim 177, wherein said compact objects are in a powder form.

180. The method of claim 177, wherein said distributing of said compact objects is by spraying.

181. The method of claim 171, wherein said coat is of a tubular structure.

182. The method of claim 171, further comprising rotating the medical implant during said step (a).

183. The method of claim 182, wherein said rotating comprises connecting the medical implant to a rotating mandrel.

184. The method of claim 183, further comprising electrospinning a second liquefied polymer onto said mandrel, prior to said step (a), hence providing an inner coat.

185. The method of claim 171, further comprising electrospinning at least one additional liquefied polymer onto said first coat, hence providing at least one additional coat.

186. The method of claim 171, further comprising providing at least one adhesion layer onto the medical implant.

187. The method of claim 184, further comprising providing at least one adhesion layer onto at least one coat.

188. The method of claim 186, wherein said adhesion layer is an impervious adhesion layer.

189. The method of claim 187, wherein said adhesion layer is an impervious adhesion layer.

190. The method of claim 186, wherein said providing at least one adhesion layer is by electrospinning.

191. The method of claim 187, wherein said providing at least one adhesion layer is by electrospinning.

192. The method of claim 183, wherein said electrospinning step comprises:

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

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

(iii) dispensing said charged liquefied polymers within said first electric field in a direction of said mandrel.

193. The method of claim 192, wherein said mandrel is of a conductive material.

194. The method of claim 193, wherein said first electric field is defined between said mandrel and a dispensing electrode being at a first potential relative to said mandrel.

195. The method of claim 193, further comprising providing a second electric field defined by a subsidiary electrode being at a second potential relative to said mandrel, said second electric field being for modifying said first electric field.

196. The method of claim 195, wherein said subsidiary electrode serves for reducing non-uniformities in said first electric field.

197. The method of claim 195, wherein said subsidiary electrode serves for controlling fiber orientation of each of said coats generated upon the medical implant.

198. The method of claim 192, wherein said mandrel is of a dielectric material.

199. The method of claim 192, wherein the medical implant serves as a mandrel.

200. The method of claim 198, wherein said first electric field is defined between the medical implant and a dispensing electrode being at a first potential relative to the medical implant.

201. The method of claim 198, further comprising providing a second electric field defined by a subsidiary electrode being at a second potential relative to the medical implant, said second electric field being for modifying said first electric field.

202. The method of claim 201, wherein said subsidiary electrode serves for reducing non-uniformities in said first electric field.

203. The method of claim 201, wherein said subsidiary electrode serves for controlling fiber orientation of each of said coats generated upon the medical implant.

204. The method of claim 171, wherein said first liquefied polymer is a biocompatible liquefied polymer.

205. The method of claim 171, wherein said first liquefied polymer is a biodegradable liquefied polymer.

206. The method of claim 171, wherein said first liquefied polymer is a biostable liquefied polymer.

207. The method of claim 171, wherein first liquefied polymer is a combination of a biodegradable liquefied polymer and a biostable liquefied polymer.

208. The method of claim 184, wherein said second liquefied polymer is a biocompatible liquefied polymer.

209. The method of claim 184, wherein said second liquefied polymer is a biodegradable liquefied polymer.

210. The method of claim 184, wherein said second liquefied polymer is a biostable liquefied polymer.

211. The method of claim 184, wherein said second liquefied polymer is a combination of a biodegradable liquefied polymer and a biostable liquefied polymer.

212. The method of claim 185, wherein each of said at least one additional liquefied polymer is independently a biocompatible liquefied polymer.

213. The method of claim 185, wherein each of said at least one additional liquefied polymer is independently a biodegradable liquefied polymer.

214. The method of claim 185, wherein each of said at least one additional liquefied polymer is independently a biostable liquefied polymer.

215. The method of claim 185, wherein each of said at least one additional liquefied polymer is independently a combination of a biodegradable liquefied polymer and a biostable liquefied polymer.

216. The method of claim 171, wherein said at least one pharmaceutical agent is Heparin.

217. The method of claim 171, wherein said at least one pharmaceutical agent is a radioactive compound.

218. The method of claim 171, wherein said at least one pharmaceutical agent is silver sulfadiazine.

219. The method of claim 183, further comprising heating said mandrel prior to, during or subsequent to said step of electrospinning.

220. The method of claim 219, wherein said heating of said mandrel is selected from the group consisting of external heating and internal heating.

221. The method of claim 220, wherein said external heating is by at least one infrared radiator.

222. The method of claim 221, wherein said at least one infrared radiator is an infrared lamp.

223. The method of claim 220, wherein said internal heating is by a built-in heater.

224. The method of claim 223, wherein said built-in heater is an Ohmic built-in heater.

225. The method of claim 183, further comprising removing the coated medical implant from said mandrel.

226. The method of claim 225, further comprising dipping the coated medical implant in a vapor.

227. The method of claim 226, further comprising heating said vapor.

228. The method of claim 225, wherein said vapor is saturated a DMF vapor.

229. The method of claim 171, further comprising exposing the coated medical implant to a partial vacuum processing.