Feb 08, 2002
By Emma Hitt, PhD
NEW YORK, Reuters Health
New synthetic implant materials that only a few years ago might have seemed "unimaginable" are providing new hope for the treatment of diseases that destroy bone, cartilage, blood vessels and other tissues, according to researchers.
The newest generation of synthetic implant materials, also called biomaterials, help prompt tissues to repair themselves and may even have applications towards treatment of diseases such as Parkinson's, arthritis and the bone-thinning disease osteoporosis, the researchers suggest.
In a review article in the February 8th issue of Science, Drs. Larry L. Hench and Julia M. Polak, from the University of London, UK, describe the possible applications of the third and latest generation of biomaterials.
This generation is an advance on previous ones because the newest biomaterials stimulate the growth of new tissue. Once they have served as a scaffold they dissolve, allowing room for growth of new tissue, the authors report.
According to Hench and Polak, 30 years ago, even the concept that a material could be transplanted and not rejected by a person's immune system "seemed unimaginable."
The first generation of biomaterials, developed in the 1960s, were inert substances used in transplant operations and were mainly designed not to provoke a rejection by the body's immune system, the report indicates.
With the second generation, "the field of biomaterials began to shift in emphasis," so that materials were designed to elicit "a controlled action and reaction in the physiological environment."
An example of this type of biomaterial is the biodegradable suture, or dissolvable stitches, which were routinely used by 1984, the authors note.
The newest generation of biomaterials is being designed to "stimulate specific cellular responses at the molecular level," Hench and Polak explain. The aim is to design glass- and foam-like materials that can serve as a scaffold and at the same time stimulate the regeneration of living tissue.
One application of these materials is to engineer the growth of tissue outside the body so that it can then be transplanted, the authors point out.
"These tissue-engineered constructs are then implanted into the patients to replace diseased or damaged tissues...and should provide long-lasting repair," they note.
"Clinical applications include repair of...cartilage, skin, and the vascular system, although stability of the repaired tissues needs improvement," the researchers add.
Another use, according to the investigators, is to implant the materials in the form of powders and solutions to stimulate tissue repair at the site of implant. These new biomaterials may even be useful in brain disorders such as Parkinson's disease and could provide the correct "microenvironment" to allow for the growth of new brain cells.
According to Hench, their most recent research suggests that seven families of genes in bone cells are upregulated by one of the materials they tested. "This, as far as we know, is the first indication that we may be able to design materials for enhancement of repair using a genetic basis for the design," he said.
"Our greatest hope," Hench told Reuters Health, "is that we can use this understanding to learn how to prevent the deterioration of bone." Even though bone might seem like an inactive substance, it is in a constant state of breakdown and repair, and biomaterials could stimulate new growth, thus preventing the loss of bone and diseases such as arthritis and osteoporosis.
"We don't know how to prevent tissue deterioration yet," he said, suggesting that such a solution may be at least 5 years off, "but at least we know how to approach the problem."
SOURCE: Science 2002;295:1014-1017.
Copyright © 2002 Reuters Limited