Synthetic Scafold to Repair Damaged Knees

When Dr. A.W. Mayo Robson performed the first ACL repair back in 1895, I doubt he ever imagined that in the future doctors would use synthetic 3-D polymers to replace torn ligaments.

Now, researchers at the University of Virginia have bioengineered a new ACL replacement using a 3-D polymeric fiber braiding process. It’s the first synthetic scaffold design to demonstrate exceptional tissue regeneration and healing, and it could lead to a promising ligament-replacement technology.
“Our goal was to regenerate the ACL using classic design principles from engineering and material that has mechanical properties that mimic the natural ACL,” says Cato Laurencin, the team leader and chairman of the University of Virginia Department of Orthopedic Surgery. His team found that it could utilize its newly developed synthetic polymer system with ACL cells to reconstruct the ligament and produce neoligament tissue. “Any solution that can be devised to speed up the healing and long-term function is hugely important to patients,” says Laurencin.
Several groups have explored ligament-like scaffolds using collagen fibers, silk, and composites, but with limited success. “There just hasn’t been very much successful work done on tissue-engineering ligaments,” says Robert Langer, a professor of chemical and biological engineering at MIT. “This [Laurencin’s team’s work] is a very significant discovery. I haven’t seen anybody do what they are doing with ligaments before.”
The ACL replacement developed by Laurencin’s team uses a clinically proven, FDA-approved biocompatible polymer, polyL-lactide (PLLA), which is frequently used in drug delivery systems, biomedical devices, bone plates, and sutures. Laurencin’s team uses the polymer to stabilize the knee while the scaffold promotes the regeneration of new ligament tissue. The polymer is an absorbable material: its mechanical properties and mass diminish with time and in a manner that permits a favorable biological response.
The design of the synthetic scaffold enables the gradual dissolution of the synthetic material and promotes optimal ligament cell growth for formation of a neoligament, explains Laurencin. Using a process that he refers to as 3-D polymeric fiber braiding, the team of researchers fabricated a 3-D scaffold by braiding the fibers of the PLLA polymer. This method enables cells to efficiently maneuver around the synthetic material and produce collagen fibers and fresh blood vessels much faster than current methods do. Braiding the ligament also gives the structure strength.
“This is the first tissue-engineered matrix for ACL to demonstrate such substantial neoligament formation, in terms of both vascularity and collagen formation,” says Laurencin. “This provides hope for being able to regenerate the ACL in humans and will hopefully pave the way for new treatment paradigms of patients.”

Read more at the Technology Review . . .