A Baltimore man became only the second patient to receive a completely synthetic trachea, to replace one ravaged by cancer.
Swedish surgeons, led by Dr. Paolo Macchiarini, director of the Advanced Center for Translational Regenerative Medicine at the Karolinska Institute, performed the transplant after removing Christopher Lyles’ trachea, which connects the nose and mouth to the lungs. Macchiarini then fashioned a new trachea from microfibers of plastic shaped into a windpipe scaffold, which was slowly saturated in a bioreactor in a solution of stem cells from Lyles’ own bone marrow. The stem cells, which can grow into the proper type of cells that make up the trachea when placed in the right environment, populated the matrix to create a functioning trachea. Because the cells growing the new trachea were Lyles’ own, Macchiarini is hoping that there will be less chance Lyles will reject the transplant.
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Lyles follows an Eritrean man who received the first such transplant in July 2011 after his trachea was also damaged by cancer.
Macchiarini has been perfecting the process of using stem cells to seed bioengineered scaffolds for organs like the trachea since 2008; in his first such procedure, he used a donor trachea to replace that of a Spanish woman, stripping the organ of its cells and coating it with the woman’s own stem cells. But using a completely synthetic, bioengineered matrix such as the one transplanted in Lyles, he says, makes the transplant safer for the patient, potentially sparing him the complications that can arise if he can’t accept the new organ.
Researchers have used similar stem cell seeding techniques to create other organs. Dr. Anthony Atala at Wake Forest University generated bladders and a urethra using scaffolds and patients’ stem cells.
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While the trachea transplant represents an important step toward using stem cell, or regenerative techniques instead of organ transplants to treat diseases like cancer, experts say there are still many unanswered questions about how the body reacts to such newly introduced tissues. Dr. Alan Trounson, president of the California Institute for Regenerative Medicine, which funds cutting edge stem cell research, said to the New York Times “It looks very functional at this stage, but there’s going to be a reaction of some kind.” Understanding any reaction that may occur, however, is part of the long but exciting process that may eventually make such transplants more routine.