First Bioengineered Blood Vessel Successfully Implanted
A bioengineered tissue is used in a vein graft at Duke University Hospital on Wednesday, June 5, 2013.
CREDIT: Shawn Rocco, Duke Medicine
A patient with late-stage kidney disease just became the first person to receive a bioengineered blood vessel implant.
The operation, performed on Wednesday, June 5 at Duke University Hospital, was the bioengineered blood vessel's first clinical trial.
Researchers at Duke and a spin-off company called Humacyte have been working on bioengineered blood vessels for almost fifteen years.
One of the major challenges in bioengineering human tissue for medical purposes is that the human body tends to reject implanted organs; the immune system will often attack these foreign cells as if they were harmful invaders.
The tissue of this artificially grown blood vessel is made from donated human cells. These cells are placed in a solution of amino acids, vitamins and nutrients, and grown around a tube-shaped mesh structure, causing the cells to form into the shape of a blood vessel.
The mesh structure is biodegradable and eventually dissolves as the cells grow around it into the desired shape. Scientists then seed the cell structure with muscle cells to strengthen it.
The researchers also discovered that pumping nutrients through the tube as it grows, in a rhythm that mimics the pulsing of a heart, helps to strengthen the vessel.
All in all, the growth process takes several months. Scientists are able to use a patient's own cells to make a personalized blood vessel, but doing so isn't cost-effective, and it often takes too long to actually be helpful to the patient. So as a last step, the cell tissue is bathed in a special solution that turns the cell structure into a structure of collagen, a type of protein group found in mammals' connective tissue.
The implant's transformation from living cells into collagen helps ensure that the patient's body won't reject it.
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In the recent operation, the bioengineered blood vessel was implanted as part of a hemodialysis, the process of flushing toxins out of the body when the kidneys are unable to do so.
During hemodialysis, doctors often try to speed up a patient's blood flow by connecting an artery to a vein. Current methods for doing this involve grafting the blood vessels with a synthetic tube, which often leads to clotting, or surgically extracting blood vessels from elsewhere in the patient's body to form the connection, which opens up the risk of infection.
In pre-clinical trials, Duke University's bioengineered blood vessel performed much better than either of these options, and it seems to be continuing to do so judging from the success of this operation.
Jeffrey Lawson, a vascular biologist at Duke University who helped develop the bioengineered vessel and also assisted in performing the surgical procedure, is confident that this breakthrough will help pave the way for bioengineering more complex organs.
"We hope this sets the groundwork for how [organs] can be grown, how they can incorporate into the host and how they can avoid being rejected immunologically," Lawson said in a statement.
"We start with [a blood vessel], and one day we may be able to engineer a liver or a kidney or an eye."