Scientists at Northwestern University say they've invented a goo — yes, a goo — that could open the door to regenerating human knee cartilage, a finding that could eventually lead to new clinical ways to rebuild knee joints and avoid invasive and expensive knee replacement surgeries.
Cartilage is the connective tissue that wraps around joints and bones, working to absorb shock, aid mobility, and protect against painful bone-on-bone friction. These are all tough — and important! — jobs, and yet cartilage doesn't naturally regenerate on its own. As a result, those with worn-down or damaged cartilage often wind up turning to knee replacement surgery. While effective, that road can be expensive and generally requires a lengthy recovery period.
That's where the goo might come in.
As the Northwestern researchers detail in their new study, published this week in the journal PNAS, they've invented a rubbery biomaterial that mimics the chemical structure of cartilage. When the biochemical goo was applied to human-like knee joints in sheep, the results were extraordinary: within six months, the study says, the scientists observed new cartilage growth in the animal subjects.
"Cartilage is a critical component in our joints," said Samuel Stupp, Northwestern professor of chemistry and study leader, in a statement. "When cartilage becomes damaged or breaks down over time, it can have a great impact on people's overall health and mobility."
"The problem is that, in adult humans, cartilage does not have an inherent ability to heal," Stupp added. "Our new therapy can induce repair in a tissue that does not naturally regenerate."
According to the study, the goo comprises cellular elements like peptides, proteins, and polysaccharides, which together form an injectable "scaffolding." This scaffolding binds to a protein called transforming growth factor beta-1 (TGFb-1), which assists in cellular regrowth and wound healing, and also works to lubricate joints with a version of hyaluronic acid, the common skincare ingredient.
The idea behind creating a scaffold for cells, rather than a straight-up cartilage replacement, is that the scaffolding offers a way for the body to rebuild itself from the inside out. The researchers' approach "should be more resistant to wear and tear," Stupp's statement continues, which ideally fixes "the problem of poor mobility and joint pain for the long term while also avoiding the need for joint reconstruction with large pieces of hardware."
The scientists specifically tested the substance in sheep — which, like humans, don't naturally regenerate cartilage — with cartilage issues in their stifle joints, which are similar in structure to human knees. Excitingly, the researchers didn't just observe regrowth in the animals' cartilage. They also found that the new cartilage was "consistently higher quality compared to the control," according to a press release.
Of course, because humans aren't sheep, it's still unclear how human knees might react. But the results clearly have the scientists excited, and applications go beyond later-life knee replacement surgeries: athletes who experience ACL tears could benefit, as could folks who suffer from degenerative diseases like arthritis.
In other words? Sheep knees might only be the beginning.
"We think our treatment could help address a serious, unmet clinical need," said Stupp.
More on health studies: Study Finds That You Should Drink Specific Amounts of Specific Types of Alcohol for Maximum Health
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