14 December 2010
Artificial lung technology could reduce the death rate for patients awaiting a lung transplant, say US scientists.
Advanced lung disease is characterised by an inability to remove carbon dioxide from the blood and reduced oxygen uptake efficiency. A shortage of donors can mean long delays and high mortality rates for those awaiting a transplant. The only technology available to aid sufferers during this time is based in intensive care units, hindering quality of life.
Now, Joseph Vacanti and coworkers at Massachusetts General Hospital, Boston, have developed a device that achieves the CO2/O2 gas exchange that, when implanted in the body, could allow patients more freedom when awaiting a transplant. Their design is a microfluidic branched vascular network through which blood flows, separated from a gas-filled chamber by a silicone membrane less than 10um thick. The network is formed by casting polydimethylsiloxane, a biocompatible polymer, on a micro machined mould.
A device that achieves carbon dioxide/oxygen gas exchange could allow patients more freedom when awaiting a lung transplant
A major challenge faced by Vacanti's team was achieving a blood pressure within the device's channels similar to that in veins and arteries. They applied computational fluid dynamics to optimise the vascular network's structure to avoid clotting induced by excessive blood pressure. 'Fulfilment of these design criteria necessitated creating channels that had variable depth throughout the network and also had precise curvature,' says Vacanti's coworker, David Hoganson.
Vacanti's device could be scaled up for implantation. According to Hoganson, an implant-sized device could be fabricated by 'stacking the functional layers of the device to achieve the necessary surface area for gas exchange'.
Jaisree Moorthy, who specialises in using microfluidics in tissue engineering at the University of Pennsylvania, says that Vacanti's device provides a very elegant solution. Compared to existing devices, Moorthy comments that it 'is more efficient due to a thinner membrane, and mimics the biological CO2/O2 transfer rate'.
In the future, Vacanti hopes to develop the device further to incorporate engineered lung tissue.