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Growing living-tissue heart valves a reality in 3-5 years

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  • Michael Korns
    Growing living-tissue heart valves a reality in 3-5 years Surgeons will soon be able to literally mend a broken heart using live tissue grown from a patient s
    Message 1 of 1 , Sep 4, 2007
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      Growing living-tissue heart valves a reality in 3-5 years

      Surgeons will soon be able to literally mend a broken heart using
      live tissue grown from a patient's very own stem cells, top
      cardiologists said Monday.

      The whole procedure -- harvesting cells from bone marrow, growing
      tissue, and surgically implanting the heart muscle or valve -- could
      take as little as six weeks and could become routine within three-to-
      five years, they reported.

      Their findings were published in a special issue of the Philosophical
      Transactions of The Royal Society B in Britain.

      One reason heart attacks are so debilitating, even when they are not
      fatal, is because the human heart -- a massive muscle surrounding
      four valves controlling the body's blood flow -- does not regenerate.
      Damaged tissue stays damaged.

      Most problems occur with age, when the old ticker simply begins to
      wear out.

      "But the highest medical need for tissue-engineered heart valves is
      in the treatment of congenital heart malformation," which affects
      nearly one percent of all newborns, Simon Hoeurstrup, lead author of
      one of the studies, told AFP.

      Artificial heart valves currently available must be periodically
      replaced as

      children grow, leading to great suffering and higher death rates than
      in adults.

      Bio-engineered heart muscle that could be grafted onto a patient's
      living tissue without fear of rejection by the immune system has long
      been a holy grail of cardiovascular medicine.

      Artificial replacements "do the job and save people's lives," said
      celebrated heart surgeon Magdi Yacoub, who coordinated the 20-odd

      "But they cannot match the elegant, sophisticated functions of living

      While durable, mechanical hardware increases the risk of bacterial
      infection in the heart's inner lining, as well as abnormalities in
      blood flow. Recipients must also take medication to prevent blood
      clots, boosting the chances of internal bleeding and embolisms.

      Cardiovascular disease, the number one killer worldwide, claimed some
      17.5 million lives in 2005, according to the World Health
      Organisation. Many of these deaths might have been avoided by timely
      surgery to implant replacement valves and heart muscle.

      There are currently two broad techniques for making bio-prosthetic
      heart valves, and both have serious drawbacks.

      Animal grafts, especially from pigs, are readily available, but
      differ in structure and tend to wear out. Human valves from donors
      work much better, but are in chronically short supply and can easily
      provoke immune reactions.

      In the tissue engineering approach favored by Yacoub and Hoerstrup,
      the patient's own stem cells -- taken from bone marrow -- are
      isolated and expanded in the laboratory using standard cell culture

      They are then "seeded" onto a special matrix in the shape of a heart
      valve that is positioned in a device called a "bioreactor" that
      tricks the cells into growing in the right shape.

      Once mature, the living-tissue heart valves can be implanted in the
      patient. The whole process unfolds in a matter of weeks.

      This procedure has already been extensively tested in sheep, but
      several years of follow up are required before it can be deemed
      effective and safe, said Hoerstrup.

      Another hurdle, he said, is that the capacity of some patients to
      yield suitable stem cells may be compromised by diseases such as

      © 2007 AFP
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