These bubble-shell chondrocytes are stained green to make them easily visible
Plekus Laboratory/University of California/Irvine
Long-ignored structural tissue found in the nose and ears has been shown to resemble bubble wrap, and harnessing it could make facial surgery, such as nose reshaping, easier.
Maxim Plekus He and his colleagues at the University of California, Irvine, first discovered the unusual texture a few years ago while studying fat cells collected from the ears of mice. “It was just a scientific accident,” he says.
The nose and ears of mice and humans contain a strong, elastic tissue called cartilage, which is also found in our joints. Conventional wisdom says that cartilage is structured similarly, no matter where it is located in the body. The cells in it do not contain much fat and are surrounded by a thick, protein-rich matrix that provides strength.
But when the researchers examined samples from the mice’s nose and ears under a microscope, they found a structure made up of cells filled with fat, also known as lipids, connected only by a thin network of protein, leading the team to call it adipose cartilage. “It looks like bubble wrap,” Plekus says.
The team found that this unusual cartilage had been observed before, but only in a brief description of its discovery in the 1850s and in a few short reports since then. To investigate further, the researchers stretched and compressed samples of fatty cartilage from the mice’s ears, and did the same for standard cartilage from the mice’s knees and ribs.
They found that adipose cartilage was softer and more stretchy, perhaps due to its higher fat content, Plekus says. This suggests that adipose cartilage has unique roles in the body compared to standard cartilage, although determining these roles requires further study, he says.
The team also found adipose cartilage in human ear and nose samples collected from medically aborted fetuses, leading them to ask whether the tissue could be grown in the laboratory for use in reconstructive or plastic surgery. Nose changes, for example, sometimes involve taking a piece of cartilage from a person’s rib.
Alternatively, transplanting stem cells could get around this, but attempts to do this for standard cartilage have been hampered by the difficulty of screening for any remaining stem cells, Plekus says, which, if transplanted, could develop into tumors. The researchers found that they were able to successfully grow adipose cartilage from human stem cells derived from embryos, and that it was much easier to detect the remaining stem cells using a dye that binds to fat in the tissue.
He says it’s too early to know how well this will work in practice until the results are replicated and the approach tested in animals and humans. Mark Grimes at the University of Montana, who was not involved in the study.
Plekus’ team is already testing face transplants using stem cell-derived adipose cartilage in mice and hopes to try it in humans soon. “If we’re optimistic, within five years,” he says.
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