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← Your body vs. Implants - Kaitlyn Sadtler

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Showing Revision 3 created 06/12/2019 by lauren mcalpine .

  1. Insulin pumps improve the lives
  2. of many of the 415 million people
    with diabetes around the world
  3. by monitoring blood sugar, delivering
    insulin,
  4. and preventing the need for constant
    finger-pricking and blood testing.
  5. These small machines include a pump and
    a needle, which can sense glucose levels,
  6. feed back to the pump,
  7. and then calculate how much insulin
    to deliver through the needle.
  8. But they have a catch: they’re temporary.
  9. Within a few days, glucose sensors have to
    be moved and replaced.
  10. And it’s not just glucose monitors and
    insulin pumps that have this problem,
  11. but all bodily implants,
    at different time scales.
  12. Plastic prosthetic knees have to be
    replaced after about 20 years.
  13. Other implants, such as those used for
    cosmetic reasons,
  14. can meet the same fate in about 10.
  15. That isn’t just a nuisance: it
    can be expensive and risky.
  16. This inconvenience happens because of
    our bodies’ immune systems.

  17. Honed by several hundred million
    years of evolution,
  18. these defensive fronts
  19. have become exceptionally good
    at identifying foreign objects.
  20. Our immune systems boast
  21. an impressive arsenal of tools to tackle,
    intercept, and destroy
  22. anything they believe shouldn’t be there.
  23. But the consequence of this constant
    surveillance
  24. is that our bodies treat helpful
    implants, like insulin pumps,
  25. with the same suspicion as they would
    a harmful virus or bacteria.
  26. As soon as the insulin pump has been
    implanted in the skin,

  27. its presence triggers what’s known as a
    “foreign body response.”
  28. This starts with free-floating proteins
  29. that stick themselves to the surface
    of the implant.
  30. Those proteins include antibodies,
  31. which attempt to neutralize the new object
  32. and send out a signal that calls other
    immune cells to the site
  33. to strengthen the attack.
  34. Early-responding inflammatory cells,

  35. like neutrophils and macrophages,
  36. respond to the emergency call.
  37. Neutrophils release little granules filled
    with enzymes
  38. that try to break down the surface
    of the insulin pump’s needle.
  39. Macrophages secrete enzymes too,
  40. together with nitric oxide radicals,
  41. which create a chemical reaction that
    degrades the object over time.
  42. If the macrophages are unable to dispatch
    the foreign body rapidly,
  43. they fuse together, forming a mass of
    cells called a “giant cell.”
  44. At the same time, cells called fibroblasts
  45. travel to the site and begin to deposit
    layers of dense connective tissue.
  46. Those enclose the needle that the pump
    uses to deliver insulin
  47. and test for glucose levels.
  48. Over time this scaffolding builds up,
  49. forming a scar around the implant.
  50. The scar functions as an almost
    impenetrable wall

  51. that might start to block vital
    interactions
  52. between the body and the implant.
  53. For example, scarring around pacemakers
    can interrupt
  54. the electrical transmission that’s
    crucial for their functioning.
  55. Synthetic knee joints may give off
    particles as they’re worn down,
  56. causing immune cells to inflame
    around these fragments.
  57. Tragically, the immune system’s attack
    can even be life-threatening.
  58. However, researchers are finding ways
    to trick the immune system

  59. into accepting the new devices we
    introduce into our bodily tissues.
  60. We’ve discovered that coating implants
    with certain chemicals and drugs
  61. can dampen the immune response.
  62. Those basically make the implants
    invisible to the immune system.
  63. We’re also making more implants
    out of natural materials
  64. and in forms that directly mimic tissues,
  65. so that the body launches a weaker attack
  66. than it would if it came across a
    completely artificial implant.
  67. Some medical treatments involve implants
  68. designed to regenerate lost
    or damaged tissues.
  69. In those cases, we can design the implants
    to contain ingredients
  70. that will release specific signals,
  71. and carefully tailor our bodies’
    immune reactions.
  72. In the future, this way of working
    alongside the immune system

  73. could help us develop completely
    artificial organs,
  74. totally integrative prostheses,
  75. and self-healing wound therapies.
  76. These treatments might one day
    revolutionize medicine–
  77. and transform, forever,
    the bodies we live in.