 
Biomaterials Research Shines Light on Cartilage Growth and Bone Repair
Fortunately, advances in biomaterials research hold promise for engineering replacement cartilage tissue that could restore a knee or other joint to its pre-injured state. Kristi Anseth, Patten associate professor of chemical engineering, is leading graduate students in creating customized photopolymers - chains of complex molecules formed using ultraviolet light - to be used in the medical treatment of joint and bone injuries. Elastic polymers or gels containing cartilage-forming cells, called chondrocytes, can be introduced to the body, providing interim strength and restoring function to the joint. The polymer is injected into an injured joint and biodegrades over time as the chondrocytes form new natural cartilage. "From a structural standpoint, cartilage is easier to engineer than organs and other tissues. Our method makes an elastic 'hydrogel' that allows cartilage to form, then subsequently degrades," says Anseth, who this year received the Dow Outstanding New Faculty Award for the American Society for Engineering Education's Rocky Mountain Section. The engineered cartilage is still not as strong as natural cartilage in the human body, however. Anseth and graduate student Brian Hutchison are collaborating with molecular biologists, orthopedic surgeons, and others to design the best possible material to meet the challenge. Anseth already has patented a new bone-healing process, which creates a similar polymer "scaffold" to aid in the repair of severe bone fractures. A customized polymer is placed inside a fracture or in the cavity where a bone tumor has been removed. The polymer maintains strength as it degrades and accelerates new bone growth through the introduction of vitamins or amino acids to the injured area. Another graduate student, Jason Burdick, is now working with Anseth to create a different sponge-like polymer that could be seeded with bone-forming cells, or osteoblasts, to accelerate healing even further. When compared with the alternative of multiple surgeries to insert and then remove stainless steel fasteners to support a fractured bone so it can heal, the benefits of photopolymers are clear. The ability to customize the polymer for a specific job is especially useful. "We now have the ability to rationally design materials to behave as we intended for the chosen application," Anseth says.  Engineering Home |
Anyone who has ever torn some cartilage knows what an important tissue this is, providing the smooth, cushioning surface for knees and other articulating joints. Unlike a bone that is broken, however, cartilage doesn't have the capacity to heal itself.