Stem cell successes

In the past week we have heard of two stem cell successes. In one a man was transplanted with a new trachea (windpipe). A 36-year-old man whose own cancerous trachea had to be removed was treated with the procedure on 9 June at the Karolinska University Hospital in Stockholm, Sweden, by Paolo Macchiarini.

No donor was needed for the new procedure. Instead the tissue was custom-built to fit the patient, then coated inside and out with his own stem cells. The treatment began after Alexander Seifalian of University College London received detailed scans of the patient's diseased trachea. Using these, Seifalian constructed a bespoke replacement from a novel polymeric material that he has developed and patented.

Two days before the operation, the team took 200 ml of bone marrow from the patient and from this extracted 40 ml of mesenchymal stem cells. By pouring these on top of the synthetic organ in a bioreactor developed by Harvard Bioscience of Holliston, Massachusetts, the trachea was successfully coated inside and out with the patient's own cells.

During surgery, Macchiarini's final touch was to add patches of the patient's nose lining to the inner surface of the trachea. These later grew into a layer of epithelial cells matching those lining the inner surfaces of the respiratory tract.

"The big conceptual breakthrough is that we can move from transplanting organs to manufacturing them,” says David Green, the president of Harvard Bioscience – although he adds that the concept would work best for simple structures such as tracheas, ureters and blood vessels.

In another stem cell development, a company called FCB-Pharmicell based in Seongnam, South Korea, became the first in the world to receive official approval for a stem-cell-based procedure to treat people who have survived heart attacks. In the newly approved procedure, stem cells are extracted from the patient's bone marrow, multiplied in the lab then injected directly into the heart through the coronary artery.

Little clinical data is publicly available to prove that the procedure benefits patients, but according to press reports last week, the company says that in trials, patients showed 6 per cent improvements in heart function six months after the procedure, compared with untreated patients.

It is important to recognize that these reports do not derive from embryonic stem cells which have to be produced from spare embryos manufactured by IVF, but from mesenchymal stem cells which come from the patient's own tissue (often bone marrow) that carries neither ethical not rejection risk.