The state of clinical development for tissue engineering of less complex parts of the body is far advanced beyond organ engineering. Organs like hearts, livers, and lungs are far more structurally diverse than, say, a trachea, and thus an acceptable biological substitute trachea is easier to build - well within the capabilities of today's laboratories. That translates into faster progress towards broader availability in the clinic:
Since 2008, eight patients have been given a new chance at life when surgeons replaced their badly damaged tracheas with man-made versions. This highly experimental technology is now moving from research labs to a manufacturing facility as a Boston-area company prepares to produce the scaffolds for growing the synthetic organs on a large scale.
Harvard Apparatus Regenerative Technology, or HART, is testing its synthetic trachea system in Russia and has plans for similar tests in the European Union this year. The company is working with the U.S. Food and Drug Administration to set up a trial in the United States as well. The synthetic windpipes are made by growing a patient's own stem cells on a lab-made scaffold. In the future, this technique could be adapted to create other organs, such as a replacement esophagus, heart valve, or kidney.
HART creates the scaffolds by spinning fibers about a hundredth of the width of a human hair into a tube that is made to fit each patient. Stem cells taken from a patient's bone marrow are then "rained down over the top of the scaffold, much like a chicken in a rotisserie." The cells grow on the scaffolds in a specialized rotating incubator for about two days before they are transplanted. About five days after the transplant, new cell types appear on the organ, including important cells that line the inner surface and help move mucous from the lungs by coughing. Eventually, blood vessels grow into the synthetic organ.