So how did this new cell elude scientists and doctors for so long? In a sense, it didn’t. Prix and his graduate students scoured centuries of scientific literature looking for traces of missing fatty cartilage. They found a clue in an 1854 German book written by Franz Leydig, a contemporary of Charles Darwin. “He did anything he could stick under the microscope,” Pryx says. Leydig’s book describes fat-like cells found in cartilage samples taken from rat ears. However, realizing that 19th-century tools could not extend beyond that observation and that a more accurate census of skeletal tissue could be valuable to medicine, Prix set out to unravel the incident. I have decided.
His team began their investigation by examining the cartilage sandwiched between thin layers of skin in mouse ears. A green dye, which preferentially stains fat molecules, revealed a network of squishy clumps. They isolated these lipid-filled cells and analyzed their contents. All cells contain the same gene library, but those genes are not always active. What genes did these cells express? What proteins were slicked inside? This data reveals that lipochondrocytes actually look molecularly very different from adipocytes.
They then asked how lipochondrocytes behave. Fat cells have the undeniable function of storing energy in the body. When your body stores energy, it increases the amount of lipid stores in your cells. When your body burns fat, your cells shrink. It turns out that adipose chondrocytes do no such thing. The researchers studied the ears of mice fed a high-fat diet and a calorie-restricted diet. Despite rapid weight gain and loss, ear fat chondrocytes remained unchanged.
“That immediately suggested that they must have a completely different role that has nothing to do with metabolism,” Plix says. “It has to be structural.”
Fatty cartilage cells are like balloons filled with vegetable oil. Although it is soft and amorphous, it resists compression. This contributes significantly to the structural properties of cartilage. Based on rodent data, comparing cartilage tissue with and without adipose chondrocytes shows a 77-360 percent increase in cartilage tensile strength, elasticity, and stiffness; It suggests being more flexible.
And its structural gifts appear to benefit species of all kinds. For example, in the outer ear of Pallas’s long-tongued bat, fatty cartilage lies beneath a series of frills, which scientists believe is tuned to the precise wavelength of sound.
The research team also discovered lipochondrocytes in human fetal cartilage. And Dr. Lee says this finding seems to finally explain what reconstructive surgeons are often observing. “Cartilage is always a little slippery,” she says, especially in young children. “You can feel it, and you can see it. It’s very obvious.”
New findings suggest that lipochondrocytes fine-tune the biomechanics of parts of our cartilage. The rigid, lipid-free cartilage protein scaffold is highly durable and is used to build weight-bearing joints in the neck, back, and ribs, one of the traditional sources of cartilage for implants. “But when it comes to things that are more complex, like ears, the tip of the nose, the larynx, where you really need flexibility and bounciness, fatty cartilage shines,” Plix says.
For procedures that involve modifying these parts of the body, Prix envisions one day growing fat cartilage organoids in dishes and 3D printing them into arbitrary shapes. However, Professor Lee cautions, “Despite 30 or 40 years of research, we are not very good at creating complex tissues.”
Although such a procedure is still a long way off, this study suggests that it is possible to grow lipochondrocytes from embryonic stem cells and safely isolate them for transplantation. . Professor Lee believes regulators will not give the go-ahead for using embryonic cells to grow tissue for non-life-threatening conditions, but he believes researchers could transplant them from adult cells derived from patients. He said he would be more optimistic if he could grow more tissue. (Prix said the new patent application he filed covers the use of stem cells from adult tissue.)
Fat chondrocytes update our understanding of what cartilage should look and feel like and why. “If you’re trying to make a nose, for example, you can sometimes use[lipid-filled cells]as a bit of filler,” Lee says. Fatty cartilage may one day be able to fill that void as a growable, transplantable tissue. Or it could lead to better biomimetic materials. “It could be both,” she says. “It’s fun to think about. Maybe that’s one of the things we’ve been missing.”
(Tag translation) Science
