In a remarkable scientific development, researchers have discovered a subtle detail in the structure of human skin that could radically change our understanding of skin aging and scar repair.
This discovery, which at first glance may seem like just a small anatomical detail, holds enormous potential for developing revolutionary cosmetic and medical treatments.
The secret lies in microscopic structures resembling tiny ripples, found in the area between the outer (epidermis) and inner (dermis) layers of the skin.
These structures are scientifically known as reticular ridges. For many years, scientists believed that these ridges formed during the early stages of fetal development in the womb, before birth. However, a research team from the Washington State University College of Veterinary Medicine has overturned this understanding. According to findings published in the journal Nature, the researchers demonstrated that these reticular ridges do not appear before birth, but rather shortly afterward.
What are dermal papillae and what is their function?
Lead researcher Ryan Driskell, an associate professor at the university, likens them to biological Velcro. These ripples firmly hold the epidermis to the dermis beneath, giving the skin its strength and elasticity. When skin is young, these papillae are deep and tightly interwoven, making the skin appear firm and plump.
As we age, these papillae gradually fade. This process leads to the appearance of signs of aging: the skin becomes thinner, loses elasticity, and begins to sag and wrinkle. Therefore, understanding how these papillae form is key to maintaining youthful skin.
It took scientists so long to discover this because of a systematic flaw in the organisms used as research models. For decades, research relied on mice and monkeys as models closely resembling humans.
"When you look at these animals, we see differences in the fur," says Shawn Thompson, PhD student and lead author of the study. "But beneath the surface, we discovered that only animals with thick skin, such as pigs, bears, and dolphins, have skin papillae similar to humans. Mice and monkeys have thin, furry skin and completely lack these papillae."
The brush bear provided compelling evolutionary evidence: the presence of these papillae led researchers to hypothesize that body size and skin density were crucial factors in the development of this structure. However, studying its evolution on a daily basis in bears is challenging, so the team turned to pigs as a more suitable model.
Pigs have thick skin similar to human skin, and its development can be precisely tracked. In collaboration with local farmers, the team collected skin samples from pigs at different ages, and analysis proved that the papillae form after birth, not before.
Driscle says, "We expected these structures to have formed before birth, so seeing them afterward was a surprise. This timing changes the way we think about skin building and the possibility of influencing it later in life."
Using advanced genetic mapping techniques, the team identified the biological pathway responsible for building these papillae: "BMP signaling protein." This protein acts as a molecular instruction set that directs skin cells to organize themselves into this complex tissue.
This discovery has enormous therapeutic importance. Since papillae atrophy with age, reactivating the BMP pathway could be the key to restoring youthful skin structure.
“This discovery is exciting because it has tremendous application potential,” says Maxime Plexus, a professor at the University of California and a co-author of the research. “BMP proteins are already FDA-approved for orthodontic applications, which paves the way for their use in treating skin aging and scars.”
In short, what seemed like a minor detail in the skin's structure has become a new window into understanding the mechanisms of aging and repair. This research not only explains skin aging but also provides a blueprint for restoring its youth in ways previously impossible. It's a reminder that the greatest scientific discoveries are often hidden in the smallest details.
