US scientists reported important progress towards building new human lungs by successfully implanting lab-cultivated cells into a rat's lungs, and by creating an artificial device on a microchip that mimics the human lung.
Yale University researchers managed to create lungs that worked from 45 to 120 minutes by using laboratory-cultivated cells and implanted them into rats, a scientific first.
Separately, researchers with the Wyss Institute at Harvard University, Harvard Medical School and Children's Hospital Boston created a device that acts like a human lung using blood vessel cells. It is about the size of a rubber eraser.
The artificial lung can be used to test the effects of new medicine and toxins on human lungs, said Wyss Institute director Donald Ingber and the study's main author.
The mini lung-on-a-chip "merges a number of technologies in an innovative way," said MIT Institute Prof. Robert Langer.
"I think it should be useful in testing the safety of different substances on the lung and I can also imagine other related applications, such as in research into how the lung functions," he added.
Both research studies appear in the June 25 edition of the journal Science.
For the first study, researchers took adult rat lungs and removed their existing cellular components.
They preserved the matrix and branching structures of the airways and vascular system, which they later used to grow new lung cells.
"When implanted into rats for short intervals of time (45-120 minutes), the engineered lungs exchanged oxygen and carbon dioxide similarly to natural lungs," the researchers said.
"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 Laura Niklason from Yale University.
"This is an early step in the regeneration of entire lungs for larger animals and, eventually, for humans," she said.
Ms Niklason however, warned that it will take years of research with adult stem cells to see if lungs can be regenerated in vitro, successfully implanted into patients, and made sure they function properly.
The Yale team found that the engineered lungs were similar to those of native tissues, and properly exchanged oxygen and carbon dioxide when implanted.
Some 400,000 people die annually in the United States of lung diseases.
Lung tissue is especially difficult to regenerate because it rarely repairs beyond the microscopic level, researchers said.
"The only current way to replace damaged adult lung tissue is to perform lung transplantation, which is highly susceptible to organ rejection and infection and achieves only 10 per cent to 20 per cent survival at 10 years," the Yale researchers said.