Penn researchers use composite nanofibers to create biomaterials

Researchers at the University of Pennsylvania have developed a composite nanofiber that acts as a tissue scaffolding to guide regrowth of damaged tendons, ligaments and meniscus tissues.

The University of Pennsylvania ("Penn," Philadelphia, Pa., USA) reported on Aug. 7 that researchers at the school have developed and validated a technology that uses composite nanofibers as a type of tissue scaffolding to guide regrowth of tendons, ligaments and meniscus tissues in patients who have suffered injuries to knees, rotator cuffs, Achilles tendons and other joints. 

The new technology provides a loose enough structure for cells to colonize without impediment, but still can instruct cells how to lay down new tissue. The findings appear online this week in the Proceedings of the National Academy of Sciences.

Robert L. Mauck, PhD, professor of Orthopaedic Surgery and Bioengineering, and Brendon M. Baker, PhD, previously a graduate student in the Mauck lab at the Perelman School of Medicine, University of Pennsylvania, conducted the research. "These are tiny fibers with a huge potential that can be unlocked by including a temporary, space­holding element," says Mauck. The fibers are on the order of nanometers in diameter.

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 that 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 sorts —­­ into damaged tissue for neighboring cells to colonize.

Increasing the proportion of the dissolving fibers enhanced the ability of host cells to colonize the nanofiber mesh and eventually migrate to achieve a uniform distribution and form a truly three­ dimensional tissue. Despite the removal of more than 50 percent of the initial fibers, the remaining scaffold was a sufficient architecture to align cells and direct the formation of a highly organized extracellular matrix by collagen­-producing cells. This, in turn, led to a biologic material with tensile properties nearly matching human meniscus tissue, in lab tests of tissue mechanics.

"This approach transforms what was once an interesting biomaterials phenomenon —­­ cells on the surface of nanofibrous mats —­­ into a method by which functional, three­-dimensional tissues can be formed," says Mauck.

Mauck and his team are currently testing these novel materials in a large-animal model of meniscus repair and for other orthopaedic applications.

Click Penn report for the original press release.