Novel and Emerging Therapies
Tanezumab is an antibody that targets nerve growth factor (NGF), which plays a significant role in pain transmission (Cattaneo 2010). Among patients with osteoarthritis (OA) of the knee, tanezumab was associated with a significant reduction in pain intensity (Felson 2011). However, in June 2010, the FDA put all trials of tanezumab on hold because a significant number of patients taking this drug experienced an unusually rapid progression of joint bone necrosis (Lane 2010). Some researchers claim this bone necrosis occurred because of overuse of the joint (due to the potent analgesic effect of tanezumab). However, the FDA is waiting for more information on the exact cause of this adverse effect before allowing trials to continue (Wood 2010; Lane2010).
Autologous stem cell transplantation, which utilizes stem cells extracted from one’s own body, as opposed to an embryo, might reverse painful joint deterioration caused by osteoarthritis (OA). It involves using undifferentiated cells that can develop into almost any tissue—new cartilage, tendons, ligaments, even bone—to replace damaged, arthritic joints (Centeno 2008).
Unlike embryonic stem cells, mesenchymal stem cells (MSCs) have already differentiated to some extent, “committing” to develop into tissues such as bone, muscle, tendon, ligament, and cartilage. They can be found in abundance in bone marrow. Under the proper conditions, MSCs can be induced to differentiate into each of their potential specific tissue types, making them ideal for implanting into damaged joints and bones (Jorgensen 2004).
By using MSCs from your own body (autologous), there is no risk of transplant rejection. There is even evidence that transplanted MSCs exert anti-inflammatory, immune-modulating influences within the joint (Ringe 2009; Chen 2008). This means they can theoretically outperform more traditional transplants, which run the risk of destruction by inflammation.
Two seminal reports presented the results of an early human case-report – an individual with a long history of chronic knee pain that proved unresponsive to surgery (Centeno 2008a; Centeno 2008b).
The patient underwent successful harvest, expansion (through platelet-derived tissue factors), and transplant of his own MSCs into his damaged knee joint. The results were compelling—just one month after the injection the patient’s cartilage surface had expanded by approximately 20%, a gain that was maintained at three months. The meniscus (cartilaginous tissue that provides structural support) was nearly 29% larger in volume at 3 months, indicating vigorous growth and remodeling of previously damaged tissue. The patient’s pain level decreased as well.
Apitherapy, the use of bee venom for medicinal purposes, including relieving joint pain, can be dated back to at least the 5th century BC (Alqutub 2011). More recently, there have been numerous anecdotal reports of bee stings dramatically improving symptoms of OA (Mayo Clinic 2009b). Bee venom, when combined with acupuncture for the treatment of OA of the knee, was associated with a substantial analgesic effect compared to traditional (needle-only) acupuncture (Kwon 2001). Researchers believe that the anti-inflammatory characteristics of bee venom can be attributed to mellitinin, a component of bee venom that is one hundred times stronger than the inflammation-reducing hormone cortisone (Alqutub 2011).