Stimulation of cell growth at implant surfaces

• US 20060129216A1
• Filed: 12/14/2004
• Published: 06/15/2006
• Est. Priority Date: 12/14/2004
• Status: Active Grant

• Current Assignee: Boston Scientific Scimed (Boston Scientific Corporation)
• Original Assignee: Boston Scientific Scimed (Boston Scientific Corporation)
• Inventors: Drasler, William J., Jenson, Mark Lynn, Hastings, Roger N.
• Granted Patent: US 7,410,497 B2
• Time in Patent Office: Days
• US Class Current: 607/115
• CPC Class Codes: A61B 2560/0219 of externally powered implanted units
• CPC Class Codes: A61B 2562/02 Details of sensors specially adapted for in-vivo measurements
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: A61B 5/076 Permanent implantations telemetry using implanted circuitry A61B5/0031; implanted stimulators for therapy A61N1/3605, A61N1/362, A61N1/372
• CPC Class Codes: A61B 5/283 Invasive
• CPC Class Codes: A61B 5/445 Evaluating skin irritation or skin trauma, e.g. rash, eczema, wound, bed sore
• CPC Class Codes: A61F 2/06 Blood vessels
• CPC Class Codes: A61F 2/86 Stents in a form characterised by the wire-like elements; Stents in the form 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: A61L 27/34 Macromolecular materials
• CPC Class Codes: A61L 27/50 Materials characterised by their function or physical properties , e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
• CPC Class Codes: A61N 1/02 Details
• CPC Class Codes: A61N 1/326 for promoting growth of cells, e.g. bone cells
• CPC Class Codes: A61N 1/3629 in combination with non-electric therapy
• CPC Class Codes: A61N 1/37512 Pacemakers

Abstract

The present invention is directed to medical devices that contain at least one tissue contacting surface that is configured to undergo a variation in surface charge in response to a time-dependent signal. Such a variation in surface charge is provided, for example, to enhance or inhibit cellular growth adjacent to, on, or within the at least one tissue contacting surface.

Claims

1. A medical device comprising a first medical device portion comprising a first tissue contacting surface that is configured to undergo a time-dependent variation in surface charge at a site of contact with a host, in response to a time-dependent signal.

2. The medical device of claim 1, wherein said variation in surface charge mimics surface charge variations that lead to enhanced or inhibited cellular growth in the natural environment with which the device is configured to make contact.

3. The medical device of claim 1, wherein said time-dependent variation in surface charge is produced based on a time-dependent signal that is provided by the host.

4. The medical device of claim 2, wherein said time-dependent signal comprises a signal that varies periodically with a heartbeat.

5. The medical device of claim 2, wherein said time-dependent signal comprises a blood pressure signal.

6. The medical device of claim 2, wherein said time-dependent signal comprises an electrocardial signal or a blood flow signal.

7. The medical device of claim 4, wherein said first tissue contacting surface is a blood contacting region that has a negative surface charge during a first portion of said signal and a less negative or non-negative surface charge during a second portion of said signal.

8. The medical device of claim 7, wherein said first tissue contacting surface has a non-negative surface charge during said second portion of said signal.

9. The medical device of claim 8, wherein said non-negative surface charge is a neutral surface charge.

10. The medical device of claim 8, wherein non-negative surface charge is a positive surface charge.

11. The medical device of claim 7, wherein the first portion of the signal is synchronized with a period of increased blood pressure and the second portion of the signal is synchronized with a period of decreased blood pressure.

12. The medical device of claim 1, further comprising an electrical stimulator that generates said variation in surface charge, said stimulator comprising a power source.

13. The medical device of claim 12, wherein said stimulator is implanted in said host.

14. The medical device of claim 13, wherein said stimulator is capacitively or inductively rechargeable.

15. The medical device of claim 12, wherein said stimulator is external to said host.

16. The medical device of claim 15, wherein said stimulator is conductively, capacitively or inductively coupled to said medical device.

17. The medical device of claim 12, wherein said first medical device portion comprises a first electrode disposed at or beneath said first tissue contacting surface, which provides said time-dependent variation in surface charge, said time-dependent variation in surface charge being effective to enhance or inhibit cellular growth adjacent to, on, or within said first tissue contacting surface.

18. The medical device of claim 17, wherein said first medical device portion further comprises a second tissue contacting surface which is configured to undergo a time-dependent variation in surface charge at a site of contact with said host, said second time-dependent variation in surface charge being effective to enhance or inhibit cellular growth adjacent to, on, or within said second tissue contacting surface, and a second electrode disposed at or beneath said second tissue contacting surface, which provides said time-dependent variation in surface charge at said second tissue contacting surface.

19. The medical device of claim 17, wherein said first medical device portion further comprises a second electrode that is disposed within said first medical device portion and is substantially electrically isolated from said host.

20. The medical device of claim 17, wherein said medical device comprises a second medical device portion, which comprises a second tissue contacting surface which is configured to undergo a time-dependent variation in surface charge at a site of contact with said host, and a second electrode disposed at or beneath said second tissue contacting surface, which provides said time-dependent variation in surface charge at said second tissue contacting surface.

21. The medical device of claim 17, wherein said first electrode is arranged in a manner that mimics an arrangement of native cells in the natural environment with which the device is con-figured to make contact.

22. The medical device of claim 19, wherein said device further comprises:

a polymer film having a first surface which contacts said host and a second surface opposite said first surface which does not contact said host, and wherein said first electrode is buried within said film proximate said first surface; and

said second electrode is buried within said film proximate said second surface.

23. The medical device of claim 17, wherein said first electrode comprises one or more conductive filaments.

24. The medical device of claim 18, wherein said first and second electrodes each comprise one or more conductive filaments.

25. The medical device of claim 17, wherein said first electrode comprises a patterned conductive film.

26. The medical device of claim 18, wherein said first and second electrodes each comprise a patterned conductive film.

27. The medical device of claim 12, wherein said stimulator further comprises a processor.

28. The medical device of claim 27, wherein said processor generates said time-dependent variation in surface charge.

29. The medical device of claim 12, further comprising a sensor that senses said signal from said host, wherein said stimulator provides said variation in surface charge in synchronization with said signal from said host.

30. The medical device of claim 29, wherein said sensor is implanted within said host.

31. The medical device of claim 29, wherein said sensor is external to said host.

32. The medical device of claim 1, wherein said first tissue contacting surface undergoes said time-dependent variation in surface charge using energy provided by said host.

33. The medical device of claim 32, wherein said first tissue contacting surface is configured to experience a phasic variation in strain when in contact with said host and wherein said first tissue contacting surface comprises a material that produces a surface charge in response to mechanical deformation due to said phasic variation in strain.

34. The medical device of claim 33, where said material is a piezoelectric or electrostrictive material.

35. The medical device of claim 34, wherein said device comprises a piezoelectric or electrostrictive film having a blood contacting surface.

36. The medical device of claim 35, wherein the polarity of said film is such that said blood contacting surface becomes negatively charged in response to increasing pressure.

37. The medical device of claim 35, wherein said film is provided in a predetermined pattern.

38. The medical device of claim 37, wherein said predetermined pattern mimics an arrangement of native cells in the natural environment with which the device is configured to make contact.

39. The medical device of claim 37, wherein the medical device comprises a lumen through which blood flows, and wherein the predetermined pattern comprises elongated segments that are oriented circumferentially with respect to said lumen, or both axially and circumferentially with respect to said lumen.

40. The medical device of claim 37, wherein the medical device comprises a lumen through which blood flows, and wherein the pattern mimics the arrangement of smooth muscle cells in native blood carrying lumens.

41. The medical device of claim 37, wherein said predetermined pattern comprises multiple elongated segments having lengths of 100 to 1000 microns and widths of 2 to 20 microns.

42. The medical device of claim 35, wherein said piezoelectric or electrostrictive film generates a surface charge variation with a variation in blood pressure that mimics surface charge variations that occur on native cell membranes.

43. The medical device of claim 35, wherein said piezoelectric or electrostrictive film includes an internal resistance that provides a high-pass filter time constant of between approximately two seconds and approximately one hundred seconds.

44. The medical device of claim 35, wherein said film is a piezoelectric polymer film.

45. The medical device of claim 35, wherein said film is a piezoelectric polyvinylidene fluoride (PVDF) copolymer film.

46. The medical device of claim 45, wherein said film has a thickness between approximately 0.1 microns and approximately 10 microns.

47. The medical device of claim 33, wherein said phasic variation in strain is due to a phasic variation in blood pressure.

48. The medical device of claim 32, wherein said first tissue contacting surface is exposed to an ion containing bodily fluid that undergoes a phasic variation in flow velocity, and wherein said implant provides a magnetic field that is perpendicular to the direction of said flow.

49. The medical device of claim 1, wherein said first tissue contacting surface is provided with a d.c. bias potential.

50. The medical device of claim 49, wherein said d.c. bias potential is provided by including molecular species at said first tissue contacting surface that exhibit a charge when said first tissue contacting surface is contacted with said host.

51. The medical device of claim 49, wherein said first medical device portion comprises a first electrode disposed at or beneath said first tissue contacting surface which provides said time-dependent variation in surface charge, and wherein said d.c. bias potential is provided by imposing a d.c. bias voltage on said first electrode.

52. The medical device of claim 1, wherein said device is selected from a vascular graft, a blood pump comprising a blood contacting chamber, an implantable drug infusion pump, a heart valve, a venous valve, a vascular stent, a blood filter, a pacemaker, a pacemaker lead, a wound bandage, an indwelling catheter, a vascular healing device, an occlusion device, a myocardial patch, and a blood access device.

53. The medical device of claim 1, wherein said first medical device portion of said medical device is adapted for implantation in a body lumen.

54. The medical device of claim 53, wherein said medical device comprises luminal and abluminal surfaces that undergo time-dependent variations in surface charge that differ from one another in polarity, amplitude, phase, or a combination thereof.

55. The medical device of claim 1, wherein said variation in surface charge is provided by generating an electrical potential between said first tissue contacting surface and an interior region of said first medical device portion that is substantially electrically isolated from said host.

56. The medical device of claim 1, wherein said variation in surface charge is provided by generating an electrical potential between said first tissue contacting surface and a second tissue contacting surface of said first medical device portion.

57. The medical device of claim 56, wherein said first and second tissue contacting surfaces are on opposite sides of said device.

58. The medical device of claim 1, wherein said variation in surface charge is provided by generating an electrical potential between said first tissue contacting surface and a location within the body of the host.

59. The medical device of claim 1, wherein said device further comprises a therapeutic agent that is released in said host.

60. The medical device of claim 59, wherein said therapeutic agent assists said surface charge in enhancing or inhibiting cellular growth.

61. The medical device of claim 59, wherein said device is adapted to electrically modulate release of said therapeutic agent.

62. The medical device of claim 20, wherein said first medical device portion is a vascular implant and said second medical device portion is adapted to make contact with solid tissue proximate said implant or with blood proximate said implant.

63. The medical device of claim 1, wherein said tissue contacting region is a porous region.

64. A method of treatment comprising implanting the medical device of claim 1 into a host.

65. A method for manufacturing the medical device of claim 35, comprising:

providing a medical device; and

applying a piezoelectric or electrostrictive polymer film on a blood-contacting surface of the medical device.

66. The method of claim 65, further comprising etching the film in a predetermined pattern.