Feb. 16, 2001

Biomaterials research leading to implants that will promote body's 'normal healing'


"At the start of the 21st century, biology is where the excitement is. It was physics in the first half of the 20th century, but biology is where we’re now seeing the big breakthroughs," said Buddy Ratner of the University of Washington.

Ratner’s reasons for this observation were the subject of his Director’s Distniguished Lecturer Series presentation, made last week before a packed auditorium. His talk, "Biomaterials That Heal," focused on the continuing collaborative work of biologists and materials scientists use to overcome the body’s natural response to foreign material.

Ratner is director of the Engineered Biomaterials Program at the University of Washington, where he and his team have devised sophisticated processes for coating artificial materials so that their surfaces can attract and bind specific proteins, which promote normal healing.

"Today we implant a large range of artificial body parts: eye lenses, hips, knees, veins, heart valves and more," Ratner said. Other items are placed in the body on a temporary basis, such as catheters.

While these devices save or improve the lives of millions of people, they sometimes offer only temporary fixes. The body’s natural response to foreign material is to wall it off with scar-like tissue, which frequently disrupts the implant’s performance and necessitates further medical intervention.

"(Artificial) biomaterials, in fact, heal much like a splinter or a bullet, which becomes permanently embedded in the body," explained Ratner. "They become coated in a layer of proteins I call ‘the enemy.’

"In fact, the oldest account we know of as an example of this process is the 9,000-year-old Kennewick man, found in Washington, who had a spearhead embedded in his hip that had healed there while he remained perfectly functional."

Ratner’s research program centers on the creation of new biomaterials, understanding their surfaces and their interactions with biological systems. Among these breakthroughs is a process in which artificial materials are coated so that their surfaces can attract and bind specific proteins, thus promoting normal healing.

"We’ve achieved, using relatively ordinary synthetic materials, the highly specific ‘lock-and-key’ fit we see in natural healing," said Ratner. "By reading the code of molecules present in the natural wound-healing process, we get the process for our engineering."

Ratner’s goal is a "stealth material that looks natural" to the biorecognition process, which triggers natural healing. "The next step is to see if an implant coated using our process actually ‘turns on’ healing in the body.

"The goal of our research is total integrated healing for biomaterials in the future," he concluded, "but it’s still a work in progress." To achieve this will require a precision surface engineering — every molecule controlled and placed in a defined position. The nanofabrication skills to do this are rapidly being developed.

For more information on Ratner’s work, see his program’s Website at http://www.uweb. engr.washington.edu/