Ioannis V. Yannas, professor of polymer science and engineering in the MIT Department of Mechanical Engineering, was recognized as one of the highest achievers in his field last week when the National Inventors Hall of Fame announced it would be inducting him at their 2015 ceremony this May. With this honor, which recognizes his invention of what has become known as "artificial skin," Yannas joins a small group of approximately 500 renowned Hall-of-Fame inventors.
Until just a few decades ago, human and pig skin were often used in burn treatments, but were commonly rejected by the body’s immune system. Immune suppressants also left patients vulnerable to infection. What's more, replacement skin often suffered from dehydration; at the time, no one had yet found a way of rebuilding skin that could maintain a normal moisture level.
In 1969, Yannas was studying the physics of collagen and the theory of viscoelasticity in polymers at MIT when he approached surgeon John F. Burke to collaborate on the problem. As chief of staff at Shriner's Burns Institute in Boston, Burke had already made significant strides in burn treatment, but was still missing a piece of the puzzle.
“He wanted something to keep the bacteria out and keep the moisture in,” says Yannas. “So I started to work on synthesizing a dressing for wounds that would speed up their closure, minimizing patients’ risk of infection and dehydration.”
Regenerating a new organ
As it turned out, Yannas’ artificial skin did more than just block infection and retain moisture — it actually helped to regenerate the skin.
At first, however, Yannas and Burke thought they had failed miserably. After several unsuccessful attempts to develop a dressing that would speed up the healing process, one of their membranes finally had an impact on the timeframe of healing — by significantly delaying it rather than speeding it up as expected. Yannas was crushed by this development.
“At that point,” he says, “I began to think that our project to help burn victims was over. Nevertheless, I could not stop myself from trying to understand what had gone wrong. I mounted an effort to understand why the collagen membrane had delayed closure. I spent two nights studying tissue samples from the various experiments. Epiphany occurred when I noticed that the dressing that had delayed closure had not produced a scar.”
In its place, says Yannas, was a strange kind of tissue he had never seen inside these wounds. It was dermis, the layer of normal skin underneath the epidermis.
The trick, he discovered, had been adding a synthetic layer of silicone on top of a layer of tissue-like “scaffolding” — a combination of molecular material from cow tendons and shark cartilage that imitated the matrix in tissues. The synthetic layer on top protects the skin from bacteria and infection and keeps the moisture in, while the organic layer below acts as a template on which new healthy skin cells and matrix can grow. This was remarkable because it is well known that, once injured, the dermis never grows back by itself in adults; instead wounds fill up with scar.
“For years, we did not understand the impact that this discovery would have,” Yannas says. “We simply thought it was a new treatment for burn victims. Eventually, it became clear that we were regenerating a new organ.”
Groundbreaking model
Harvard Medical School Professor Myron Spector, a close collaborator of Yannas’s for more than 20 years and an expert in biomaterials and tissue engineering, says, “In addition to resulting in a highly successful treatment for a broad spectrum of skin injuries and diseases, which alone would have been a life’s achievement, the research that Professor Yannas has conducted over the past three decades in developing a collagen-based regeneration template has led to many significant advancements. He has proved the validity of certain principles guiding regeneration and has provided a groundbreaking model for medical-device development and what is now termed ‘translational research.’"
Yannas’ regeneration principles and the collagen scaffolding he invented have generated at least three start-ups founded by prior students, postdoctoral fellows, and residents, with products to treat defects in skin, peripheral nerves, the meniscus of the knee, and articular cartilage.
Yannas is a member of the National Academy of Sciences (Institute of Medicine) and the American Association for the Advancement of Science; a founding fellow of the American Institute of Medical and Biological Engineering; and a charter member of the Biomedical Engineering Society, among others. He has previously won numerous awards, including the Doolittle Award of the American Chemical Society and the Clemson Award for Applied Science and Engineering from the Society of Biomaterials.
Yannas will be inducted along with 13 others, including John Burke and fellow MIT graduate Edith Clarke, at the 2015 National Inventors Hall of Fame induction ceremony in May. For more information, visit invent.org.
