The world's first synthetic trachea. The pink coloration is due to stem cells that have differentiated to tracheal tissue.

Regenerative medicine history was made on June 9th at Stockholm’s Karolinska University Hospital when doctors successfully gave Andemariam Beyene a synthetic trachea. The 36-year old African native, who is working towards a PhD in geology in Iceland, was diagnosed in 2008 with tracheal cancer. Despite treating it aggressively with radiation and chemotherapy the tumor continued to grow. When the tumor had grown to the size of a golfball and began to occlude Beyene’s breathing. It became clear that different measures needed to be taken or he would die. Trachea replacement was the treatment of choice but they didn’t have a donor and time was running out.

So the doctors decided to make a new trachea from scratch.

The surgery brought together experts from three continents. Dr. Paolo Macchiarini at Karolinska University Hospital, who led the surgery, collaborated with scientists in the UK to engineer a nanocomposite trachea scaffold. With measurements acquired through 3D scans the scaffold was molded to the exact dimensions of Beyene’s trachea. Like a real trachea it was a kind of flexible tube segmented with stiff rings. After being shipped to Sweden, the scaffold was placed in a bioreactor provided by Harvard Bioscience, along with stem cells extracted from Beyene’s bone marrow. Chemicals inside the bioreactor induced the stem cells to differentiate into trachea tissue and they grew into the nanocomposite mold which was porous like a sponge. Amazingly, the synthetic trachea was ready to implant in just two days. “Stem cells from the own patient were growing inside and outside,” Macchiarini told CNN. “The structure was becoming a living structure.” The operation lasted 12 hours, during which Dr. Macchiarini removed the tumor and the diseased section of the trachea and replaced it with its living duplicate.

Harvard Bioscience's "InBreath" bioreactor needed only two days to turn a nanoparticle composite into a trachea.

A major risk with trachea transplants–or, for that matter, transplants of any organ–is that the donor organ will be rejected by the recipient’s immune system. Up until now trachea scaffolds have been provided by organ donors. They’re cut to size and the outer layers of cells are washed off. To prevent rejection from the host the scaffolds are coated with stem cells from the recipient. The advantages of a purely synthetic trachea are two-fold: you don’t need to wait for a donor and the implant is a perfect fit. And the fact that it takes only two days before it’s ready for implantation means more patients can be treated earlier and thus have a greater chance to be cured. Karolinska University Hospital also acknowledged that the treatment could greatly benefit children for whom donor tracheas are much less available compared to adults.

Bioengineered trachea transplants have come a long way in a short period of time. It was only 2008 when Dr. Macchiarini himself became the first to implant a trachea covered with the recipient’s own stem cells. This past January he led a heroic surgery to restore the voice box of a woman from California who’d been incapable of speaking for more than a decade. Beyene’s transplant is only the surgeon’s 11th trachea transplant overall.

This is the fourth time in a year and a half that we’ve reported on Dr. Macchiarini’s remarkable work. It’s indicative of a field and its pioneer moving rapidly forward. It’s also a superb example of multi-disciplinary collaboration. In comments to BBC, Dr. Macchiarini referred to nanotechnology as a “new branch of regenerative medicine.” He went on to suggest that the same approach could be used to repair or replace other organs.

In fact, the entire field of regenerative medicine seems to be moving rapidly. Last year a “magic powder” was used to grow back fingertips. Just months ago the same substance was used to grow back a Marine’s thigh muscle. And it seems like every time we turn around there’s another breakthrough in stem cell research. It’s one of the most exciting pursuits in science today.

It’s been over a month now since Beyene received his new trachea. He’s still in the hospital and he’s still pretty weak. But he’s looking forward to finishing his studies and rejoining his family back in Eritrea. “I was very scared, very scared about the operation,” he told BBC. “But it was live or die.”

An exciting pursuit indeed, made even more so by the people it helps.

[image credits: Harvard Bioscience]
image1: Trachea
image2: Bioreactor

Peter Murray was born in Boston in 1973. He earned a PhD in neuroscience at the University of Maryland, Baltimore studying gene expression in the neocortex. Following his dissertation work he spent three years as a post-doctoral fellow at the same university studying brain mechanisms of pain and motor control. He completed a collection of short stories in 2010 and has been writing for Singularity Hub since March 2011.