Andemariam Beyene, an African cancer patient from Eritrea had made his peace with his life, and talked about his impending death. Doctors found a golf ball-sized tumor growing in his windpipe, and despite several treatments with radiation and surgery to remove it, it kept growing. He was in pain, and out of options.
As a last resort, he went to the Karolinska Instute in Stockholm, Sweden to visit Dr. Paolo Macchiarini, who wanted to make a new windpipe for Mr Beyene from his own cells and spun plastic. This seemed like the medical equivalent of a “Hail Mary” pass in football, but it seemed worth a shot.
There is a precedent for such a procedure, since between 2008 and 2011, Dr. Macchiarini fitted nine people with new tracheas. These tracheas were built from the patient’s own stem cells that were grown on scaffolds made from tracheas that had been completely stripped of all their cells. These “decellularized” scaffolds work well, but they have one large drawback: .they required the existence of a pre-existing trachea from a human or an animal. Therefore, for Mr. Beyene, Dr. Macchiarini used a different procedure that built the scaffold from scratch out of plastic.
For this procedure, a mold of Mr. Beyene’s trachea was made from porous, fibrous plastic. This mold was then seeded with bone marrow stem cells and grown in a bioreactor. The bioreactor contained culture medium that turned much like a rotisserie. After one day and a half of growth in the bioreactor, the trachea was implanted into Mr. Beyene’s body.
Even though this procedure had been successful performed in pigs, it had never been tried on a human. Mr. Beyene was convinced by Dr. Macchiarini to give it a try. Now, the 39-year old African who lives in Iceland is back with his wife and children, getting to know people he thought he would never know. His strength is improving every day and can even run a little.
The synthetic scaffold used for Mr. Beyene’s windpipe was made by scientists at University College London. This mold was made to exact specifications so that it would perfectly fit inside Mr. Beyene’s chest. Then stem cells from his bone marrow were cultured in the laboratory and dripped with a pipette over the scaffold, in the same way that you baste a turkey. Then this whole thing is grown in a bioreactor that circulated fresh culture medium at regular intervals while spinning the scaffold and the cells. Macchiarini is quite sure that the original cells that are seeded onto the scaffold are dead. He suspects that the dying stem cells leave a host of chemicals in their stead that summon other stem cells from the bone marrow to come and seed the scaffold.
The windpipe is lined with several different types of cells. Some of them secrete mucus, which serves as a kind of adhesive tape for dust particles and microorganisms that are inhaled. The mucus is then moved to the top of the throat by a host of cells with hair-like extensions that move back and forth like oars on a Viking boat. At the top of the throat, the mucus is swallowed and destroyed in the stomach. Also, the windpipe is well endowed with blood vessels to feed the tissues oxygen and nutrients from the bloodstream.
Mr. Beyene’s windpipe was found to contain some mucus-producing cells at fives months after the surgery. At follow-up, it was also clear that his windpipe bled when nicked. Mr. Beyene hopes to return to Eritrea some day, but for now he will stay in Iceland, since he is close to Stockholm for his regular check-ups. He had some scar tissue from the implant that was impeding his breathing, but that has been removed. He still needs regular check-ups, but he is doing well.
Five months after implanting Mr Beyene with his engineered windpipe, Dr. Macchiarini implanted an American patient named Christopher Lyles with a tissue engineered windpipe made from a plastic scaffold and his own stem cells. Mr. Lyles’ windpipe was made with an improved type of scaffold fabricated from smaller plastic fibers. Mr. Lyles returned home to Maryland, by died in March of 2012. While the cause of death has not been released, Dr. Macchiarini has been told that his implant was not the cause of his death and that up until the time of his death, it had been functioning normally. Dr. Macchiarini has also implanted engineered windpipes into two Russian patients who have been discharged fro the hospital and are doing well.
While these procedures are remarkable feats of stem cell biology, tissue engineering and medical intervention, we must admit that these techniques are still experimental and are hugely expensive (half a million dollars per procedure). Dr. Macchiarini’s dream it to some day design drugs that induce the stem cells to build a new trachea within the patient from the inside out. This way, no surgery is required and the patient would have a rebuilt windpipe.