HOUSTON -- (July 19, 2010) -- Bioengineers from Rice University's BioScience Research Collaborative have won a $1.7 million grant from the National Institutes of Health to develop an injectable mix of polymers and adult stem cells that can spur the growth of new cartilage in injured knees and other joints.
"Millions of people live with pain, limited mobility and arthritis that often result from cartilage injuries, particularly those to the knee," said Rice researcher Kurt Kasper, a principal investigator on the new five-year grant. "By combining just enough of a patient's own stem cells with the proper mix of growth factors and polymers, we hope to allow the body to do something it cannot normally do -- fill in small gaps with healthy, new bone-protecting cartilage."
The research lies at the cutting-edge of basic science and engineering, and Kasper said a human treatment, if it proves feasible, would still be at least a decade away.
In joints like the knee, elbow and shoulder, a thin layer of cartilage covers and protects the bones at the point where they meet and rotate against one another. This "articular" cartilage is one of many types of cartilage found in the body, and it has wondrous material properties. For example, it's so impact-resistant and resilient that no currently available synthetic materials can stand up to the punishment it endures.
Because no synthetics can suitably replace articular cartilage, and because the body has almost no natural ability to repair it, Kasper and other researchers are looking for ways to reinforce and expand upon the healing abilities the body already has.
Rice's research team on the new project includes Kasper, a faculty fellow in the Department of Bioengineering, and Antonios Mikos, the Louis Calder Professor of Bioengineering, professor in chemical and biomolecular engineering and director of Rice's Center for Excellence in Tissue Engineering.
The team will use mesenchymal stem cells (MSCs), a type of stem cell that the body uses naturally to repair broken bones, injured skin and other tissues. Researchers have long known that MSCs can be coaxed into becoming cartilage-generating cells with the right combination of growth factors.
"We aim to find the optimal formulation of MSCs and growth factors for regenerating articular cartilage," Mikos said. "We will deliver that mix in a nontoxic, biodegradable polymer system that can be injected as a liquid and that gels quickly to form a temporary support matrix to guide the growth of the new cartilage."
Kasper said a unique aspect of the study is its focus on developing techniques that will allow the newly formed cartilage to attach naturally to the underlying bone in the joint. To do this, the team hopes to develop a two-layered system where the upper layer of articular cartilage is grown atop a segment of newly formed bone. A different formulation of growth factors and MSCs will be needed in each layer, and tests in animals will be used to determine the optimal mix that might be needed for future clinical translation to humans.