Imagine your body as a bustling city, where each neighborhood has its own unique roads and buildings. In this city, white adipose tissue (WAT), commonly known as body fat, is more than just a storage space for extra energy. It’s a complex community, with blood vessels acting as highways that deliver nutrients and messages to keep everything running smoothly.
But what happens when the city grows too fast, like during obesity? Scientists wanted to find out, so they studied how obesity affects the blood vessels in different types of fat in male mice. They focused on two main “neighborhoods”: subcutaneous WAT (sWAT), which sits under the skin, and visceral WAT (vWAT), which wraps around the organs deep inside the belly.
First, the researchers noticed that not all fat is created equal. People with more fat in their bellies (vWAT) tend to have worse health problems like diabetes and heart disease than those who carry fat under their skin (sWAT). This hinted that the blood vessels in these two types of fat might behave differently.
To explore this, the scientists fed some mice a high-fat diet to make them obese, while others ate a normal diet. They then looked closely at the blood vessels in both sWAT and vWAT. What they found was striking: obese mice had fewer blood vessels in both types of fat, but the loss was more pronounced in the fat around the organs. Even in healthy mice, sWAT had more blood vessels than vWAT, suggesting it’s better equipped to handle extra fat.
Digging deeper, the team used advanced techniques to study individual cells from these blood vessels. They discovered a variety of endothelial cells – the cells that line blood vessels with different jobs. Some helped with nutrient transport, others with building new vessels, and a special group called fenestrated endothelial cells acted like tiny filters, allowing important substances to move in and out of the fat tissue.
Here’s the twist: these fenestrated cells were found only in sWAT and disappeared in obese mice. The researchers learned that a molecule called VEGFA was crucial for keeping these cells healthy. When VEGFA was blocked, the fenestrated cells vanished, making it harder for sWAT to function properly.
The story doesn’t end with mice. When the scientists checked human fat tissue, they found the same pattern: people with obesity had fewer of these special filtering cells in their subcutaneous fat.
This research reveals that obesity doesn’t just increase fat, it changes the very structure and function of blood vessels in different fat depots. Understanding these changes could help scientists find new ways to treat or prevent the health problems linked to obesity, by protecting the “highways” that keep our fat tissue healthy.
