Two year old Hannah Warren has recently become the youngest person ever to benefit from stem cell research, when doctors recently performed an experimental procedure to give her a new windpipe.

Hannah Warren Photo

Hannah was born with a very rare congenital defect, caused by the overlapping effect of various lack of development in her neck and resulted in her being born without a windpipe or trachea.

Sadly, as you might expect from such a severe mutation, the survivability rate is very low, less than 1%. For all of her short life, Hannah had been hooked up to respiratory equipment in a hospital in Seoul, South Korea, with doctors not expecting her to live past the age of six. However, her father managed to track down Dr Paolo Macchiarini, an expert in regenerative medicine, and arrange for her to be transferred to Children’s Hospital, Illinois, for the surgery.

Using cell culturing techniques, the surgeons were able to perform an experimental procedure to generate a new windpipe for Hannah. It involved obtaining a sample of the young girls’ stem cells from her bone marrow, and growing them in culture in a bioreactor, which maintains the correct internal conditions to allow the cells to multiply without them clumping together. Constructing an underlying structure out of plastic nanofibres, the cells adhered to the scaffold and multiplied. The entire construct was then cut to shape for the operation.

Drs Macchiarini and Mark Holterman undertook a gruelling nine-hour operation to transplant the artificial throat into the toddler. These tracheal transplants are rarely performed, and the effects of grown organs are still not fully understood. Luckily though, three weeks later it appears to have been successful. Due to the cells in the new tissue having originally come from Hannah herself, there is no chance of her body rejecting them, eliminating the need for immunosuppressant drugs, and increasing her chances of a normal life.

While it was successful, operations of this type are still experimental, and with good reason. Permission for operating on such a young child in this way was only obtained due to the lack of options and her slim chances of survival without it. Research is still on-going into better techniques for growing more complex cell patterns and finding more suitable growing scaffolds. In spite of the transplanted windpipe being made deliberately oversized, Hannah will need successive alterations over time, and long assessment before it is known if she will be able to eat and speak without aid. But for now at least, both her, and her parents, can at last breathe easily.