Researchers in Japan say they have confirmed blood flow in bioengineered lungs transplanted into mice. They say the lungs were made using human cells.

Assistant Professor Suzuki Takaya at the Institute of Development, Aging and Cancer of Tohoku University, and other researchers, say they removed all cells from mouse lungs. Collagen fibers and basement membrane, however, were maintained.

The group says they then injected human cells into these scaffolds to create lungs, including blood vessels, and transplanted the bioengineered organs into other mice.

The researchers say engineering complex organs, such as lungs, remains a major challenge. They say the mouse-scale lung bioengineering platform developed in their study could facilitate a scale-up to larger, human-scale organ bioengineering in the future.

Suzuki says the architecture of mammalian lungs is basically consistent across species, including mice, swine and humans. He believes the new platform is an important step toward conducting research using swine and other large animals to transplant bioengineered lungs into humans.