‘Dancing Molecules’ Could Be the Key to Cartilage Regeneration
By Irene Yeh
September 10, 2024 | Osteoarthritis affects more than 528 million people around the world. Cartilage in joints wears down, and bones rub against each other, causing pain, stiffness, and mobility issues. Current treatments slow down cartilage degeneration, though patients inevitably need expensive joint replacement surgery. However, researchers at Northwestern University discovered “dancing molecules” that might be the key to the first cartilage regenerative therapy.
Led by Samuel I. Stupp, Board of Trustees professor of material science, chemistry, medicine, and biomedical engineering, the Northwestern research team applied dynamic molecules to damaged human cartilage cells and found that they were able to produce protein components needed for cartilage regeneration in only three days.
How ‘Dancing Molecules’ Work
The dancing molecules were developed as a component of the Stupp laboratory’s bioactive supramolecular materials, which are designed to signal cells to carry out certain instructions. Due to being softer than conventional polymers, these supramolecular polymers can be used as liquids, hydrogels, and so on. But perhaps their most notable trait is the ability of the molecules within the materials to change positions and move, hence their moniker. This is distinctly different from the building blocks of ordinary polymers, which have very limited ability to change positions.
The dynamic nature of dancing molecules is “extremely effective” at signaling living cells, according to Stupp. By attaching signals onto the dancing molecules, the receptors that crowd the outer membrane of cells can effectively receive these signals. The team learned to control the movements of these molecules—whether they move a lot or move a little—and discovered that the more they moved, the more they “talked” to the cells to begin producing the proteins for cartilage regeneration.
“We have discovered something that’s pretty universal,” says Stupp. “When materials are designed to be bioactive, meaning that they are signaling cells to do certain things—for example, instructions to regenerate… a very useful thing is to develop dynamic materials where molecules have a lot of movement, and those movements help them signal the receptors of cells more efficiently and more robustly.”
Discovering the Regeneration Potential
The team discovered how the dancing molecules help with regeneration back in 2021. They conducted an experiment where they applied the dancing molecules to the spinal cords of paralyzed animals. The results showed that the molecules contained the right signals needed to repair the spinal cord, and the animals regained the ability to walk after just four weeks (Science, DOI: 10.1126/science.abh3602)
“Then we said, ‘We should really be looking more broadly and see if this phenomenon applies to the regeneration of other tissues,’” recalls Stupp. The human body has some tissues that do not regenerate, such as the spinal cord, brain, and cartilage. The team decided that cartilage was the next tissue they should test. The result was that the dancing molecules were effective in the regeneration of cartilage.
Stupp also mentions that the dancing molecules can be used to help with bone regeneration. While bones do naturally repair themselves, some areas are more difficult, for example when severe fractures occur. In addition, elderly patients and patients with osteoporosis, a disease where bone mass and density decreases, have a harder time healing from serious bone injuries. But the movement of the molecules combined with the signals attached to them may trigger the bone cells to regenerate and grow denser bone mass more efficiently.
“You still need technology to be able to regenerate bone effectively,” explains Stupp. “If you have spinal fusion surgery, for example… because your disc is degenerating or something like that, you have to grow bone in the spine, and that’s difficult to do because the bone is not naturally there.”
Stupp confirms that the team is now testing the molecules on bone regeneration. A study is expected to be published in the near future.
Bringing Bioactive Materials to the Clinic
Ultimately, the team’s expectation is to introduce its platform of supramolecular therapies into products that the FDA can approve for clinical trials, which will eventually make their way into clinics and to patients. The FDA considers the ‘dancing molecules’ therapies as drugs or as drug-device combinations, which means they require further scrutiny, experiments, and preclinical tests relative to devices.
Stupp also encourages clinicians and physicians to pay attention to the development of highly bioactive materials. “Bioactive materials are a new thing, and we’ve been pioneers in that area.”
Stupp’s company, Amphix Bio, has the option to license this technology from Northwestern and plans to continue developing the science behind these dancing molecules to further improve the efficacy of bioactive supramolecular materials.