These bubble-wrap cartilage cells have been stained green for easy visualization
Plikus Laboratory/University of California/Irvine
Not to mention the long bony tissue found in the nose and ears resembles bubble wrap, and harnessing it could facilitate facial surgery, such as nose reshaping.
Maxim Plikus He and his colleagues at the University of California, Irvine, first saw the unusual tissue a few years ago while analyzing fat cells taken from mouse ears. “It was just a scientific accident,” he says.
The noses and ears of both mice and humans have a strong but flexible tissue called cartilage, which is also found in our joints. Conventional wisdom says that cartilage is structured the same no matter where it is in the body. Its cells do not contain much fat and are surrounded by a thick, protein-rich matrix that provides strength.
But when the researchers examined mouse nose and ear samples under a microscope, they found a structure made up of fat-filled cells, also known as lipids, held together only by a thin network of proteins, which the team named lipocartilage. “It looks like bubble wrap,” Plikus says.
This unusual cartilage had been noticed before, the team found, but only in a brief account of the discovery in the 1850s and a few brief reports since then. To investigate further, the researchers stretched and compressed samples of lipocartilage from mouse ears, and did the same with standard cartilage from mice’s knees and ribs.
They found that lipocartilage is softer and more stretchy, probably due to its high fat content, Plikus says. This suggests that lipocartilage has unique roles in the body compared to standard cartilage, although identifying these requires further study, he says.
The team also found lipocartilage in human ear and nose samples from medically aborted fetuses, suggesting that the resulting tissue can be grown in the lab for use in reconstructive or cosmetic surgery. Nasal alterations, for example, sometimes involve taking a piece of cartilage from a person’s rib.
Growing them from stem cells could prevent this, but attempts to make standard cartilage have been hampered by difficulties in screening the remaining stem cells, Plikus says, which, if transplanted, can turn into tumors. The researchers found that they could successfully grow lipocartilage from embryonic-derived human stem cells, and that it was much easier to detect the remaining stem cells using a dye that attaches to tissue fat.
It’s too early to know how it will work in practice until the findings are replicated and the approach is tested in animals and humans, he says. Mark Grimes at the University of Montana, who was not involved in the study.
Plikus’ team is already testing facial implants with stem cell-derived lipocartilage in mice and hopes to test them in humans soon. “If we’re optimistic, within five years,” he says.
Topics:
