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ST04 stops cartilage degradation and regenerates cartilage.



Osteoarthritis (OA) is the most common chronic condition of the joints, affecting approximately 27 million Americans.

Globally as of 2010, approximately 250 million people had osteoarthritis of the knee (3.6% of the population). One in two adults will develop symptoms of knee OA during their lives and the disease population is growing faster than the general population.


There is no cure, but treatments are available to manage symptoms.


In OA, the cartilage breaks down, causing pain, swelling and problems moving the joint. As OA worsens over time, bones may break down and develop growths called spurs. Bits of bone or cartilage may chip off and float around in the joint. In the body, an inflammatory process occurs and cytokines (proteins) and enzymes develop that further damage the cartilage. In the final stages of OA, the cartilage wears away and bone rubs against bone leading to joint damage and more pain.



Without the protective effects of proteoglycan the degeneration of cartilage begins.


While osteoarthritis is a degenerative joint disease that may cause gross cartilage loss and morphological damage to other joint tissues, more subtle biochemical changes occur in the earliest stages of osteoarthritis progression. The water content of healthy cartilage is finely balanced by compressive force driving water out and hydrostatic and osmotic pressure drawing water in. Collagen fibres exert the compressive force, whereas the Gibbs–Donnan effect and cartilage proteoglycans create osmotic pressure which tends to draw water in.


However, during onset of osteoarthritis, the collagen matrix becomes more disorganized and there is a decrease in proteoglycan content within cartilage. The breakdown of collagen fibers results in a net increase in water content. This increase occurs because whilst there is an overall loss of proteoglycans (and thus a decreased osmotic pull), it is outweighed by a loss of collagen. Without the protective effects of the proteoglycans, the collagen fibers of the cartilage can become susceptible to degradation and thus exacerbate the degeneration. Inflammation of the synovium (joint cavity lining) and the surrounding joint capsule can also occur, though often mild (compared to the synovial inflammation that occurs in rheumatoid arthritis). This can happen as breakdown products from the cartilage are released into the synovial space, and the cells lining the joint attempt to remove them.



Unique, dual mode of action stops cartilage degradation and regenerates cartilage 


ST04 works anti-catabolic and pro-anabolic.


ST04 is based on the protein CD-RAP, a cartilage specific gate keeper and rescue protein. 

The binding of CD-RAP to different targets is the molecular basis for its multimodal functionality in cartilage. This multimodal functionality of CD-RAP allows a unique approach to stop the cartilage degradation and to regenerate damaged cartilage in osteoarthritis.    

  • Anti-catabolic effect by protecting cartilage proteoglycan from cleavage by proteases.

  • Pro-anabolic effect by inducing anabolic cascade in osteoarthritis cartilage explants

    • Regulators of chondrogenesis

    • Cartilage matrix proteins: Col2

    • Chondrocyte maturation genes

CD-RAP inhibits release of pro-inflammatory cytokines and thus reduces inflammation.
CD-RAP allows less activation of nociceptive neurons and reduces pain.
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