According to a report by Reference News on September 5, as reported by Popular Mechanics on August 20, when most people think of “skin,” what comes to mind is actually the epidermis—the outermost layer of skin that renews approximately every month. However, the main functional activities of the skin occur in the dermis (the middle layer located between the epidermis and subcutaneous tissue), where adipose tissue acts as a shock absorber and connects to the underlying bones and muscles. This complex three-dimensional structure of the skin (the largest organ in the human body) contains nerve endings, hair follicles, glands, and blood vessels.
Severe wounds and burns can be repaired through epidermal grafting, but scientists have yet to find a method to replicate the dermis for more ideal wound healing techniques. Why is that? Because the structure of the dermis is too complex. However, two studies published in the journal Advanced Materials have made promising progress. The research, led by scientists from Linköping University in Sweden, was conducted on mice. The study created “skin in a syringe”—an injectable 3D printed skin implant containing live cells that can be used to treat severe wounds.
The lead author of the studies, John Yunker from Linköping University, stated in a media release: “The structure of the dermis is extremely complex, and we cannot cultivate the dermis in the lab. We do not even fully understand all of its components. This is why we and many other researchers believe that perhaps we can transplant the basic components of the dermis and then let the body generate the dermis itself.”
The researchers started with fibroblasts, a type of connective tissue cell that is relatively easy to extract from the human body and cultivate in the lab. They built a scaffold using gelatin microspheres for the cells to grow on. The real breakthrough was the development of a gel made from hyaluronic acid, a naturally occurring substance that hydrates the skin and lubricates joints. When the scientists mixed the gelatin microspheres with this gel, they found that the mixture would turn into a liquid when subjected to slight pressure. This is a practical feature for creating skin grafts that can be injected through a syringe. Once injected into the body, it returns to a gel-like structure.
Yunker stated in the release: “We observed that these cells could survive, and it was clear that they would produce various substances necessary for generating new dermis. Additionally, blood vessels would form within the graft, which is crucial for the survival of the tissue in the human body.”
Blood vessels are key for delivering oxygen and nutrients to cells. In the second paper, the research team detailed how they cultivated blood vessels using a hydrogel composed of 98% water. This hydrogel serves as the basis for artificial blood vessels, helping to maintain the viability of cells within these high-tech skin grafts.
Co-author Daniel Ali from Linköping University stated in the release: “These hydrogel fibers have excellent elasticity, and we can even tie them into knots. They can form micro-tubes that can transport liquids and allow blood vessel cells to grow inside them.”
This is good news for developing the next generation of skin grafts, and the successful cultivation of artificial blood vessels will also aid in the development of advanced organoids. Organoids are clusters of cells that resemble miniature organs. Due to the lack of sufficient oxygen and nutrients for the cells at the center of organoids, they gradually die, which overall limits the growth of organoids. These artificial blood vessels are expected to help scientists break through the current size threshold for organoid growth.
The dermis layer is a key layer for maintaining skin health. Mastering effective methods for repairing the dermis layer will save countless lives in the future. (Source: Reference News, copyright belongs to the original author, please contact for removal in case of infringement)
