Bioengineered organs, still largely the stuff of sci-fi, may have just moved a step closer to reality with reports that scientists have successfully implanted lab-made lung tissue into living rats.
The fully functional tissue can exchange oxygen and carbon dioxide, the key role of the lungs.
The scientists--led by a team at Yale University--used a chemical treatment to remove all existing cells from adult rat lungs, keeping the structure of the airways and vascular system intact to later serve as a sort of "scaffold" for the growth of new lung cells.
They then cultured a combination of lung cells using a bioreactor designed to mimic the fetal lung environment and repopulated the "decellularized" rat lung with the engineered cells. When implanted into rats for short intervals of 45 to 120 minutes, the new tissue exchanged gas in a manner similar to that of natural lungs.
The scientists, who detail their work in a Thursday issue of the journal Science, acknowledge that it may be some time before scientists can generate fully functional lungs in vitro, but they nonetheless are touting their research as a promising development in the quest to regenerate lung tissue.
"This is an early step in the regeneration of entire lungs for larger animals and, eventually, for humans," said Laura Niklason, a Yale professor and vice chair of the Departments of Anesthesiology and Biomedical Engineering and lead author of the study, which was funded by Yale and the National Institutes of Health. (Decellularization has also been used in experiments to rebuild a human heart).
Adult lung tissue, for its part, has limited regeneration capacity, so the primary therapy for severely damaged lungs is transplantation. That procedure is highly susceptible to organ rejection and infection and achieves only 10 percent to 20 percent survival at 10 years, according to some statistics.
Lung disease, including lung cancer, emphysema, and cystic fibrosis, accounts for about 400,000 deaths each year in the United States, according to figures provided by Yale. Lung cancer is still the most common cause of cancer death, according to the American Lung Association.
Meanwhile, in other promising artificial-lung-related news, a separate group of scientists has created a coin-size "lung on a chip" that mimics real lungs and could be used to test drugs and toxins.
The researchers, Don Ingber and his team at Harvard University, detail their dual-chambered microdevice in the same issue of Science, saying it could provide a low-cost alternative to animal and clinical studies for drug screening and toxicology applications.