Scientists at Washington State University have discovered that tiny structures in human skin may hold the secret to youthful appearance and better scar healing. Remarkably, humans, pigs, and grizzly bears possess these structures, known as rete ridges, while monkeys do not.
Rete ridges are microscopic ridges and valleys under the skin that anchor the outer layer, the epidermis, to the inner layer, called the dermis. This connection gives skin strength, elasticity, and flexibility. As people age, these ridges gradually flatten, which makes the skin thinner, weaker, and more prone to sagging and damage.
For decades, scientists believed rete ridges formed before birth. They thought this happened during fetal development. However, the WSU research team discovered something new. They found that these structures actually form shortly after birth. Using pig skin as a model, the researchers tracked the ridges. They tracked how the ridges formed, day by day. They found a key molecular signal called BMP (bone morphogenetic protein). This signal directs skin cells to arrange into these complex patterns.
“This discovery changes how we understand skin development,” said Ryan Driskell, associate professor at WSU’s College of Veterinary Medicine and senior author of the study, which was published in the journal Nature. “Knowing how these structures form gives us a roadmap for restoring them later in life, which could slow skin aging and improve healing after injuries or surgeries.” Many common laboratory animals, such as mice and monkeys, lack rete ridges, making their study challenging. “People often look at animals and notice differences in fur, but rete ridges are beneath the skin surface,” explained Sean Thompson, a doctoral student at WSU and first author of the study. “Animals with thicker skin, like pigs, dolphins, and grizzly bears, have rete ridges similar to humans, which improves them models for this research.”
While studying grizzly bears helped researchers understand how body size affects skin structure, it was pigs that allowed for precise monitoring of ridge formation. By collaborating with local farmers, the team collected pigskin samples from birth through early development.
This careful sampling showed exactly when and how rete ridges form, which was a major surprise because the structures were expected to exist before birth.
The research also highlighted BMP signaling, a pathway already approved by the FDA for certain medical uses, including bone and dental treatments. Activating this pathway in older skin may restore lost ridges, improve scar repair, and help treat skin conditions such as psoriasis.
“This is very exciting because it has real-world applications,” said Maksim Plikus, a professor at the University of California, Irvine, and co-author of the study. “We may be able to use BMP proteins to rejuvenate aging skin or reduce scar formation, building on treatments that are already approved for humans in other areas.” Beyond human health, this discovery could improve livestock care. Understanding how rete ridges form may allow breeders to develop pigs and other animals with skin that is better suited to different climates, making them healthier and more resilient.
Driskell and his team have filed a provisional patent for their findings. The study involved WSU’s Bear Research, Education and Conservation Center, local farmers, the University of Washington Birth Defects Research Laboratory, and clinical partners at Spokane Dermatology.
The National Institutes of Health and the USDA Agricultural Research Service supported this research through the Resilient Livestock Initiative. It reveals how rete ridges form and identifies the molecular signals that guide them. These findings open new opportunities to maintain strong, resilient skin. They may also help slow visible signs of aging and improve wound healing. In the future, sagging skin, wrinkles, and stubborn scars might no longer be unavoidable challenges.
