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Fortified Hydrogel Cartilage Regeneration Technique Devised

Knee brace (


Researchers at École polytechnique fédérale de Lausanne (EPFL) in Switzerland developed a method for delivering regenerative drugs at the right place and time to repair damaged cartilage tissue. The team from EPFL’s biomechanical orthopedics and polymers labs published advance results this week of their proof-of-concept tests in the journal Biomaterials (paid subscription required).

Because cartilage has no blood vessels, cells that produce cartilage in knees and other joints can respond to treatments only if they are stimulated at the same time by movement. When joints are moving, cartilage cells known as chondrocytes activate receptors that respond to the body’s growth factors, and thus can respond to treatments that help regenerate damaged cartilage.

Dominique Pioletti, director of EPFL’s biomechanical orthopedics lab and one of the senior authors of the paper, notes in a university statement that the receptors are active for only a limted amount of time, after about 5 to 20 minutes of repetitive movement. Thus, the solution had to meet this timetable.

The solution also takes advantage of the heat generated from movement of the joint. Pioletti, with polymer lab director Harm-Anton Klok and other EPFL colleagues, created a viscous matrix from hydrogel, fortified with tiny nanoscale bubble particles — 1 nanometer equals 1 billionth of a meter — plus transforming growth factor-beta (TGF-beta), a therapeutic agent.

In lab tests, the EPFL team found the joint generates enough heat to reduce the size of the nanoparticles about one-third, after a series of repetitive movements of a simulated joint for 5 to 8 minutes. The smaller nanoparticles open up gaps in the hydrogel matrix. These gaps make it possible for a colored dye, simulating the therapeutic TGF-beta, to flow in and fill the newly-opened gaps.

The researchers envision implanting the fortified hydrogel matrix with minimally-invasive arthroscopic surgery in joints with cartilage damage, followed by physical therapy to mobilize the joint and activate the hydrogel. While the EPFL team proved the concept in the lab, they still need to perform animal tests and human trials to bring the technique to market. EPFL is seeking partners to develop the process further.

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