Bioengineered Tissue Repairs Damaged Knee Cartilages

A new study by scientists at the University of Bristol, UK has found that knee cartilage injuries can be effectively repaired by tissue engineering, and that osteoarthritis does not stop the regeneration process. Tissue engineering uses a mixture of biology, chemistry and materials science to grow tissues in the lab just like those in the body. The new study is the first to look in detail at what happens to tissues after they have been implanted in patients. The tissue engineering method used in this study involved isolating cells from healthy cartilage removed during surgery from 23 patients with an average of 36 years. Cartilage cells donated by patients were grown in culture for 14 days. After that, the researchers seeded them onto scaffolds made of esterified hyaluronic acid-a compound that occurs naturally in cartilage and grew them for another 14 days on the scaffolds. The cells and scaffold were then inserted to fix tears of up to 11 square centimeters in the knee cartilage of the patients. More than a year later analysis showed the cartilage had matured successfully, even in patients with osteoarthritis. Osteoarthritis, or degenerative arthritis, is a condition most common in the elderly, where cartilage slowly disappears from joints. "In these patients it seems to mature even better, suggesting it might be possible to treat patients with that condition, not just accident patients," said Anthony Hollander, ARC professor of rheumatology and tissue engineering at Bristol University who led the study. An average of 16 months later the researchers examined the health of the engineered tissue. Hollander's team used two methods to study the maturation of the cartilage. The first involved injecting antibodies attached to a fluorescent dye into the cartilage. An imaging device was then used to count the number of proteins in the cartilage to which the antibodies bound. The researchers also used an "amino acid analysis" technique to extract the joined amino acids that link cartilage proteins. These were separated to determine if they were the type found in mature or immature cartilage. In both tests, in just under half the patients, the team found all the hallmarks of natural mature cartilage, showing the engineered tissue was thriving in these patients. "We're the first to formally show cartilage implanted into damaged patients matures," says Hollander. (Ref : Times of India dated July 10, 2006)