An international research team has made an exciting discovery in the field of skeletal tissue, which could significantly enhance regenerative medicine and tissue engineering.
An international research team led by the University of California, Irvine has uncovered a new type of skeletal tissue that holds enormous promise for the fields of regenerative medicine and tissue engineering.
Typically, cartilage gets its strength from an external extracellular matrix, but “lipocartilage,” located in the ears, nose, and throat of mammals, is distinct because it’s filled with fat-containing cells known as “lipochondrocytes.” These cells provide robust internal support, allowing the tissue to remain soft and elastic, much like bubble wrap.
The findings, which have been published online in the journal Science, reveal that lipocartilage cells can create and maintain their own reservoirs of lipids, keeping their size stable. Unlike regular fat cells, known as adipocytes, lipochondrocytes do not change in size based on food intake; they neither shrink nor expand.
“The durability and flexibility of lipocartilage make it ideal for adaptable body parts like earlobes or the tip of the nose, which opens up exciting opportunities in regenerative medicine and tissue engineering, especially for facial injuries or defects,” stated Maksim Plikus, a professor of developmental and cell biology at UC Irvine and the corresponding author of the study. “Typically, reconstructing cartilage necessitates taking tissue from the patient’s rib, which is both painful and invasive. In the future, it may be possible to derive patient-specific lipochondrocytes from stem cells, refine them, and use them to create living cartilage that meets individual needs. Techniques like 3D printing could enable these engineered tissues to be shaped specifically, providing innovative solutions for treating congenital defects, injuries, and various cartilage disorders.”
The existence of lipochondrocytes was first noted by Dr. Franz Leydig in 1854, who observed fat droplets in the cartilage of rat ears; however, this discovery had been largely overlooked until now. Thanks to modern biochemical techniques and advanced imaging, researchers at UC Irvine have thoroughly studied the molecular biology, metabolism, and structural significance of lipocartilage in skeletal tissues.
The team also identified the genetic mechanisms that hinder the enzymes responsible for breaking down fats and help limit the absorption of new fat molecules, effectively securing the lipids stored in lipochondrocytes. When the lipids are removed, lipocartilage becomes stiff and brittle, which emphasizes the critical role of these fat-containing cells in maintaining the tissue’s durability and flexibility. Furthermore, they discovered that in certain mammals, like bats, lipochondrocytes can form complex structures, such as parallel ridges in large ears, potentially improving their hearing by influencing sound wave modulation.
“The discovery of the unique lipid characteristics of lipocartilage challenges long-standing biomechanical beliefs and opens the door to numerous research possibilities,” remarked Raul Ramos, the study’s lead author and postdoctoral researcher in the Plikus lab specializing in developmental and regenerative biology. “Future studies will focus on understanding how lipochondrocytes maintain their stability over time and delve into the molecular processes that dictate their structure and function, as well as investigate cellular aging mechanisms. Our research highlights the diverse functions of lipids beyond mere energy storage and suggests innovative applications of their properties in tissue engineering and medicine.”
The research team comprised health care experts and academics from the U.S., Australia, Belarus, Denmark, Germany, Japan, South Korea, and Singapore, alongside members from the Serrano Animal & Bird Hospital in Lake Forest and the Santa Ana Zoo.
This research was supported by various prestigious institutions, including the W.M. Keck Foundation, the Chan Zuckerberg Initiative, and numerous grants from the National Institutes of Health and the National Science Foundation, among others.
