Knee Ligaments Generated from Adult Stem Cells

Originally Published MDDI March 2002

R&D DIGEST

Rupture of the anterior cruciate ligaments (ACLs) is among the most common forms of knee injury, particularly among individuals who engage in sports. For athletes, treatment has typically entailed having surgery followed by using crutches for several weeks, jogging after waiting several months, and a return to full athletic activity after about six months. An estimated 15% of individuals treated for ACL injury, however, never attain full preinjury levels of activity.

Now, a tissue engineering strategy developed by researchers at Tufts University (Boston) may allow treatment of ACL injuries by mechanically and biologically engineering new ligament tissues from adult stem cells.

Greg Altman, a Tufts doctoral candidate, has conducted the research on the ligament engineering strategy over the past four years, working under the guidance of David Kaplan, director of Tufts bioengineering center and John Richmond, MD, professor of orthopedic surgery at Tufts medical school. The patented ACL product being developed can be custom engineered from a patient's or donor's adult stem cells obtained from bone marrow.

To create the custom-made ligaments, the harvested cells are cultured in vitro in a specially designed bioreactor with a collagen or other suitable biodegradable matrix. The cells are then stimulated to develop into living tissue by using multidimensional, mechanical forces to mimic ligament movement in the body. The bioengineered ligaments can be stored in a facility until needed by the patient or donor and then implanted immediately following knee joint trauma. For example, the engineered ligaments could be grown and "banked" for athletes prior to knee trauma so they will be readily available at the time of reconstruction.

Says Altman, "The technology for this tissue repair and ligament growth could fundamentally change the way we treat this very common injury." He also suggests that the engineered tissue could reduce the recovery time to weeks instead of months, compared with current surgical techniques.

Altman's drive to develop an alternative treatment for ACL injuries stems in part from his own experience as an athlete. Altman was a preseason All-American football player at Tufts in the fall of 1996 when he had his season-ending ACL injury. He later served as an assistant coach for the Tufts football team. Long-term trials of the ACL implants in goats are expected to begin later this year.

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