A Yale University team has successfully implanted laboratory-made lung tissue into rats - which were then able to use it to breathe.
The Yale researchers took adult rat lungs and removed their existing cellular innards, while keeping the external cell structure and
vascular system to use later as scaffolds for the growth of new lung cells.
They then cultured various lung-specific cells on this scaffold, using a new bioreactor designed to mimic some aspects of the fetal lung environment.
They found that the cells repopulated the framework with functional lung cells. And, when implanted into rats, the engineered lungs exchanged oxygen and carbon dioxide similarly to natural lungs for up to three hours.
"We succeeded in engineering an implantable lung in our rat model that could efficiently exchange oxygen and carbon dioxide, and could oxygenate hemoglobin in the blood," said lead author Professor Laura Niklason.
"This is an early step in the regeneration of entire lungs for larger animals and, eventually, for humans."
Lung disease accounts for around 400,000 deaths each year in the US. The Yale team says a great deal more research must be done to see if fully functional lungs can be regenerated in vitro, implanted and kept functioning long-term.
Niklason says that to produce fully-functioning human lungs, years of research with adult stem cells will be needed.
In another new development, a team at Harvard has developed what it calls a 'lung-on'a-chip', made using human lung and blood vessel cells. It's intended to be used for testing the effects of environmental toxins, absorption of aerosolized therapeutics and the safety and efficacy of new drugs.