A team at University College London has designed and fabricated the polymer scaffold that was recently used in the first fully engineered trachea transplant.
The trachea — which is made up of around 70 per cent of UCL’s novel polymer and 30 per cent of stem cells from the patient’s own bone marrow — has been completely accepted by the patient’s immune system.
‘They put a camera inside after six days and the cells had grown really nicely — you wouldn’t see a difference between a native trachea and ours,’ said Prof Alex Seifalian of UCL, who worked alongside transplant surgeons at the Karolinska University Hospital in Stockholm.
Previous attempts at trachea transplants have shown limited success. In those procedures, a donated trachea was used and the cells stripped away to leave the underlying collagen scaffold. The scaffold was then seeded with the recipient’s own stem cells and transplanted.
‘Mechanically, it’s simply not strong enough. Some of them just collapse and get holes through them, so you get patients coming back for repeat procedures,’ Seifalian said.
The team began experimenting in around 2004 with artificial nanocomposite scaffolds. ‘We work with more than 100 nanocomposites and, through a combination of chance and a little expertise, we developed this one,’ Seifalian added.
The team’s method involves a CT scan of the patient’s diseased trachea, which is used to make an exact glass-mould replica. The mould is then bathed in a chemical polymer mixture.
The key step in the fabrication process involves introducing salt into the mixture then extruding it to create nanopores and tiny surface structures.
This allows the stem cells to attach more easily when they are seeded in a special bioreactor for around three days prior to transplantation.
Seifalian said that six patients were now on the waiting list for the procedure — which does not require any immunosuppressive drugs.