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More hope for lab-grown lungs

Lung tissue grown in culture functioned for six hours when transplanted into living rats, reports a study in Nature Medicine today.

Last month, researchers from Yale University performed the first ever transplant of bioengineered lung tissue into a living organism. In their experiment, the tissue performed its gas-exchange functions for two hours when transplanted into rats. (Science advance online publication, DOI: 10.1126/science.1189345).

The present study, led by Harald Ott at Harvard University Medical School in Boston, Massachusetts, took a very similar tack. Like the Yale team and two other previous studies, Ott and his colleagues used the lungs’ own extracellular structure, carefully stripped of cells, as a matrix on which to grow their bioengineered lung tissue.

The teams’ success means suggests that “this approach of lung decellularization is definitely one whose time has come,” bioengineer Laura Niklason, who led the Yale team’s work, wrote in an email.

This is not the first organ that Ott’s team has used this technique to build a new organ. Two years ago, Ott, then at the University of Minnesota, created functioning bioengineered rat hearts by taking a dead heart, removing all its cells, and then seeding it with living cardiac cells (Nat. Med. 14:213-21, 2008).

In the current study, after adding human lung cells back to this matrix, Ott’s team, like Niklason’s, grew up the tissue in a specially made bioreactor. Upon confirming that the tissue could conduct gas exchange in a Petri dish, the Boston researchers transplanted the tissue into rats in which the left lungs had been removed. Anatomical measurements and oxygen flow studies showed that the new lungs were functioning.

The scientists note that the animals were briefly able to breathe through the transplanted lung, several elements of the procedure need to be improved – for example, the transplanted tissue did not fully regenerate.

Still, writes Niklason, “The fact that two laboratories independently developed similar approaches and got similar results means that this is a robust technique that will progress in the future.”

Image: A recellularized rat lung in a bioreactor / Harald C. Ott.


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