Polymers Construct Injured Tendons, Meniscus

Scientists from the University of Pennsylvania have developed a technology that uses polymers to construct a composite nanofibrous scaffold on which cells can colonize to repair torn tendons and ligaments.

Many laboratories have developed treatments for ligament tears in knees, Torn meniscusrotator cuff injuries, and Achilles tendon ruptures using scaffolds from nano-size fibers. However, the fibers’ widespread use in orthopedics has been slowed because cells do not colonize on the scafforlds if the fibers are packed too tightly, reports PhysOrg.

The method the Penn scientists use, however, creates space between the fibers. “These are tiny fibers with a huge potential that can be unlocked by including a temporary, space-holding element,” says Robert Mauck, a professor of orthpaedic surgery and bioengineering, at the university. His research has been published in the Proceedings of the National Academy of Sciences.

The space between the fibers is on the order of nanometers in diameter. The method is described in the following way:

Using a method that has been around since the 1930s called electrospinning, the team made composites containing two distinct fiber types: a slow-degrading polymer and a water-soluble polymer that can be selectively removed to increase or decrease the spacing between fibers. The fibers are made by electrically charging solutions of dissolved polymers, causing the solution to erupt as a fine spray of fibers which fall like snow onto a rotating drum and collect as a stretchable fabric. This textile can then be shaped for medical applications and cells can be added, or it can be implanted directly — as a patch of sort — into damaged tissue for neighboring cells to colonize.

The more dissolving fibers that were used, the better the ability of the host cells had to colonize on the nanofiber mesh, and migrate to achieve a uniform distribution and form a three-dimensional tissue. Although more than 50% of the initial fibers are removed, the remaining scaffold has enough architecture present to align cells and direct the formation of an extracellular matrix by collagen-producing cells. In turn, this process leads to a material with a tensile strength rivaling human meniscus tissue, the scientists say.

“This approach transforms what was once an interesting biomaterials phenomenon — cells on a surface of nanofibrous mats — into a method by which functional, three-dimensional tissues can be formed,” Mauck says. He believes that the technique will eventually find widespread applications in regenerative medicine.

Source: “New composite nanofibers next chapter in orthopaedic biomaterials,” PhysOrg, 8/7/12
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