Credit: © 2009 Wiley

Our lungs and the inside of the chest cavity are lined by thin membranes called pleura, and the space between the inner and outer pleura, which contains fluid, allows the lungs to expand without friction. It is common for the inner pleura to be injured after a lung operation and this is often repaired using fibrin adhesives. However, complications can occur because the adhesives cause the pleura to stick to each other. Researchers in Japan have now shown that nanosheets made from alternating layers of common wound-dressing materials can repair the inner pleura of wounded dogs without this complication.

Using the layer-by-layer method, Shinji Takeoka and colleagues1 made ultrathin (∼75 nm) sheets composed of alternating layers of chitosan and sodium alginate. The nanosheet — which is released from its support and transferred to the injured tissue by adding water — is transparent and can withstand the normal pressures in the lung. When deposited on a hole in the lungs of beagle dogs, the nanosheet followed the shape of the defect, and within five minutes blood clots typical of a wound healing process formed. Cells replaced the clots after three days and new blood vessels formed after seven days. The defect was indistinguishable after 30 days and, importantly, the inner and outer pleura did not stick.

This method of wound repair differs from using fibrin adhesives because the nanosheets provide a scaffold for healing. As their mechanical properties can be easily tuned, the nanosheets are also expected to be able to repair other organs.