At thirty years old, Claudia Castillo had such a bad case of tuberculosis that the single mother had difficulty taking care of her two children. "I was coughing all the time," she said. "I couldn't walk very far and I couldn't say more than a few words at a time before becoming breathless." The part of her windpipe (trachea) that attaches to her lung so was badly damaged by the disease that the only conventional option was to have her left lung removed, which carries significant risks and a high mortality rate.
Fortunately for her, she was offered a new and experimental procedure, which she accepted. The plan was to grow a new windpipe in the lab with her own stem cells and then transplant it back into her body. She agreed, and doctors proceeded to take stem cells from her bone marrow as well as cells from her lungs. They then "seeded" those cells into a donated windpipe that had previously been stripped of all of the donor's cells so that all that was left was the scaffolding, which scientists call "extracellular matrix" (ECM). Finally, the organ was incubated in the lab for three days, after which the team of doctors transplanted the new windpipe with Claudia's own cells into her body.
Ten days after the procedure, Claudia was released from the hospital. Two months later, her lung function tests were at the better end of the normal range for a young woman and she reported that she had gone dancing and swimming in the Spanish resort destination of Ibiza. Months later she was still doing fine and doctors confirmed that, because her own cells were used, there was no danger of her body rejecting the transplant. Clearly, Claudia's operation was a huge success. Her disease, which would have been fatal or severely disabling just years ago, has now been completely cured owing to advances in an exciting field called "tissue engineering."
And growing part of a windpipe is only the beginning. Dr. Doris Taylor's cardiovascular team at the University of Minnesota managed to grow a rat heart in their lab. "When we saw the first heart beats, we were speechless," said a member of the team. As the other doctors had done with Claudia Castillo's windpipe, Taylor's lab stripped a rat heart of its cells so that all that was left was the scaffold, or the structure of the original organ. Researchers then repopulated the scaffold with cells from newborn rat hearts and coaxed the organ to beat on its own. It doesn't take a lot of imagination to predict where this research will go next. Dr. Taylor is currently repeating the experiment on pigs, not only because their hearts are closer in size to human hearts, but also because pig hearts are already used for replacement parts for some human heart patients.