A study published in the January 15, 2014 issue of the Journal of Bone and Joint Surgery found that knee surgery patients who received an injection of stems cells into the meniscus roughly a week after surgery experienced less osteoarthritis pain and did not have complications. The researchers also found that the stem cells may help facilitate regeneration.
Knee arthroscopy is a common procedure, but has a failure rate of 20 to 24%. Patients also face an increased risk of developing osteoarthritis following the surgery. Currently, restorative procedures are limited; this is a major reason why success with stem cells could be a major step forward for patients.
Mesenchymal stem cells (MSCs) are one of the most-studied types of stem cells, and in animal studies the have been found to stimulate regeneration of the meniscus. MSC cells divide into new cells that differentiate as connective tissues, repairing and replacing lost tissue in the knee.
The research team, based at the University of Southern California, developed the study to investigate the use of MSCs to alleviate pain and regenerate cartilage following a menisectomy. In the study, 55 patients who had a partial medial meniscectomy received a single injection into the knee 7 to 10 days after their procedures. A first group received an injection of 50 million MSCs, a second group got 150 million MSCs, and the control group was injected with sodium hyaluronate (this is what the MSCs were suspended in in the other injections).
Afterward, the researchers followed up with study participants after 6 weeks, 6 months, one year, and two years after the surgery. They looked at the patients’ MRIs, and also took patients’ self reports of pain and knee function.
The research team found that treatment with MSCs was safe, and that there was a small amount of regeneration in those treated with the stem cells. The more dramatic results were in pain relief: Patients with osteoarthritis who had received stem cells reported greater pain relief than patients in the control group who had the same condition. Prior to the treatment, both groups had reported similar amounts of pain from osteoarthritis. Patients who did not have osteoarthritis who were treated with MSCs also reported decreased pain over time.
Though this study only looked at a very small number of patients, it does provide evidence that this type of regenerative medicine is safe and effective at treating joint pain. Additionally, the study provides Level 1 evidence, which is the highest level of evidence in medical research. Continuing research into stem cell therapies will hopefully lead to better understanding of how they can be used to alleviate chronic pain and regenerate tissue.