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Tissue Engineering
Using Growth Factors to Enhance Cartilage Repair
Target Condition: Joint pain due to damaged or diseased cartilage
Traditional Approach: Sugery, over-the-counter pharmaceuticals
New Approach: Stimulation of damaged tissue to repair itself via tissue engineering
Progress: Several promising growth factors are under investigation
Investigator Dr. Sally Frenkel
Joint pain is a major cause of disability not just in middle-aged and older people, but also among those who suffer sports injuries and other forms of trauma. The pain is usually caused by the injury itself and subsequent degeneration of the cartilage at the joint surface.
The effectiveness of widely advertised over-the-counter pharmaceuticals (most notably glucosamine and chondroitin sulfate) are unproven in scientific studies. One common surgical treatment involves scraping away damaged areas of cartilage; this is a stopgap measure to relieve pain, not a cure, and it may lead to further deterioration. Another approach involves transplanted chondrocytes (cartilage cells); this is still an experimental procedure that requires two operations. As a last resort, joint replacement is recommended.
A long-time goal of Dr. Frenkel’s research has been to find new ways of repairing lesions in cartilage so as to prevent the future onset of arthritis and obviate joint replacement. For the last 15 years, she has focused on designing a device to stimulate cartilage to heal itself, something it is not normally capable of doing.
How growth factors can help repair cartilage Microphotographs of the cartilage surface of rabbit knee implanted with carrier device containing cartilage cells, or growth factor, or untreated device: (top) Device alone results in uneven surface, and little normal cartilage matrix (the tissues are stained red); (center) device with cells induces formation of a smooth, regular surface, but little matrix stain is seen; (bottom) device containing growth factor results in smooth surface with healthy matrix staining.
A variety of implant systems have been developed by orthopaedic researchers. The majority involve materials designed to deliver replacement cells to the damaged area in order stimulate new cartilage growth as replacement for cells lost to injury or normal wear and tear over time. While these materials are compatible with cell survival and are eventually incorporated into the joint surface, this approach requires that healthy cells be surgically collected from the patient, then grown to large numbers in the laboratory, followed by a second surgery for implantation.
Ideally, if a device could be designed to stimulate the cells already present in the joint to repair the injury, surgery to collect the cells could be bypassed, reducing both patient pain and costs. An initiative recently instituted in our laboratories employs natural substances called growth factors in implants in lieu of cells. We anticipate that these factors will attract cells to the site of injury and stimulate them to produce a repair cartilage that will regenerate the damaged joint surface and permanently relieve pain. A regenerated surface would also prevent further deterioration of the joint to arthritic conditions. Early results of our short-term studies indicate that growth-factor-treated-implants induce a repair as good as those using cell-seeded devices. Long-term studies in large animals, now in the planning stage, will gauge the success of this approach in producing a permanent solution to this currently debilitating problem.
Using Growth Factors to Enhance Cartilage Repair
Target Condition: Joint pain due to damaged or diseased cartilage
Traditional Approach: Sugery, over-the-counter pharmaceuticals
New Approach: Stimulation of damaged tissue to repair itself via tissue engineering
Progress: Several promising growth factors are under investigation
Investigator Dr. Sally Frenkel
Joint pain is a major cause of disability not just in middle-aged and older people, but also among those who suffer sports injuries and other forms of trauma. The pain is usually caused by the injury itself and subsequent degeneration of the cartilage at the joint surface.
The effectiveness of widely advertised over-the-counter pharmaceuticals (most notably glucosamine and chondroitin sulfate) are unproven in scientific studies. One common surgical treatment involves scraping away damaged areas of cartilage; this is a stopgap measure to relieve pain, not a cure, and it may lead to further deterioration. Another approach involves transplanted chondrocytes (cartilage cells); this is still an experimental procedure that requires two operations. As a last resort, joint replacement is recommended.
A long-time goal of Dr. Frenkel’s research has been to find new ways of repairing lesions in cartilage so as to prevent the future onset of arthritis and obviate joint replacement. For the last 15 years, she has focused on designing a device to stimulate cartilage to heal itself, something it is not normally capable of doing.
How growth factors can help repair cartilage Microphotographs of the cartilage surface of rabbit knee implanted with carrier device containing cartilage cells, or growth factor, or untreated device: (top) Device alone results in uneven surface, and little normal cartilage matrix (the tissues are stained red); (center) device with cells induces formation of a smooth, regular surface, but little matrix stain is seen; (bottom) device containing growth factor results in smooth surface with healthy matrix staining.
A variety of implant systems have been developed by orthopaedic researchers. The majority involve materials designed to deliver replacement cells to the damaged area in order stimulate new cartilage growth as replacement for cells lost to injury or normal wear and tear over time. While these materials are compatible with cell survival and are eventually incorporated into the joint surface, this approach requires that healthy cells be surgically collected from the patient, then grown to large numbers in the laboratory, followed by a second surgery for implantation.
Ideally, if a device could be designed to stimulate the cells already present in the joint to repair the injury, surgery to collect the cells could be bypassed, reducing both patient pain and costs. An initiative recently instituted in our laboratories employs natural substances called growth factors in implants in lieu of cells. We anticipate that these factors will attract cells to the site of injury and stimulate them to produce a repair cartilage that will regenerate the damaged joint surface and permanently relieve pain. A regenerated surface would also prevent further deterioration of the joint to arthritic conditions. Early results of our short-term studies indicate that growth-factor-treated-implants induce a repair as good as those using cell-seeded devices. Long-term studies in large animals, now in the planning stage, will gauge the success of this approach in producing a permanent solution to this currently debilitating problem.