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Stem Cell Therapy for Knee Osteoarthritis

Scientists investigate the safety and effectiveness of a potential stem cell treatment for knee osteoarthritis.

Arthritis is a broad term used to describe stiffness and pain in the joints. There are two main types of arthritis, osteoarthritis and rheumatoid arthritis. Rheumatoid arthritis is an autoimmune disease, this is where the immune system attacks the tissues in the joints. Osteoarthritis is the most common type of arthritis and is a degenerative disease of the connective tissue. Chondrocytes are the cells that are responsible for producing cartilage, the spongy tissue between the bones. If these cells die the body is no longer able to produce or repair damaged cartilage. When the cartilage is worn away by normal mechanical stress the bones rub together. This causes chronic pain and discomfort which leads to disability and limited mobility. Until recently, it was thought that the immune system didn’t play a major role in osteoarthritis but it is now thought that inflammation can contribute to the degradation of cartilage.

Current treatment for osteoarthritis

There is no cure for osteoarthritis and the current treatments only help manage the symptoms and delay the progression of the disease. Low-impact exercise such as swimming, improved diet to encourage healthy weight preventing stress on the joints, and physiotherapy are all prescribed to help patients. Non-steroidal anti-inflammatory medications are sometimes used to help with the pain. In some instances, opioids are prescribed for pain management despite the fact they are highly addictive. In the most severe cases, major reconstructive joint surgery is used to replace the damaged joint.

What are stem cells and how can they help?

What if it were possible to stop the degradation of the cartilage and replace the chondrocytes? This is what stem cell therapy hopes to achieve. Adult stem cells are a special type of cell that is scattered throughout the body. These cells are responsible for helping regenerate our tissues. A good example of this regeneration is red blood cells. We make 200 billion new red blood cells every day and the adult stem cells that are responsible for giving rise to red blood cells are found in the bone marrow. If stem cells naturally replenish our tissues can they be used to replenish the chondrocytes in patients with osteoarthritis?

Could stem cell therapy help cure osteoarthritis?

Scientists have been investigating the use of mesenchymal stromal cells to treat osteoarthritis. These adult stem cells give rise to bone, cartilage, connective and fat tissues and are also found in the bone. The mesenchymal stromal cells are thought to help treat osteoarthritis in a number of different ways. The first is that these cells may mature into functional chondrocytes that are capable of replenishing cartilage and replacing the damaged tissues. Mesenchymal stem cells are capable of stopping inflammation and tamping down the immune response. Researchers think this is important in helping to combat osteoarthritis because it prevents the chondrocytes that are already in the joint from dying.

Scientists use bone marrow transplants to help treat arthritis

In a recent Canadian study published in Stem Cells Translational Medicine, scientists wanted to know if it would be safe to use mesenchymal stromal cells to treat patients with osteoarthritis. This was the first clinical trial of its kind to take place in Canada. This clinical trial was a phase I/II trial which means the main goal of the study was to determine whether or not stem cell treatment was safe. The group enrolled 12 patients (seven men and five women) in the trial. They were aged 40-65 and had osteoarthritis in the knee. The scientists then extracted bone marrow from the hip of each patient. They then isolated the mesenchymal stromal cells and grew these cells on a petri dish until there were enough cells to transplant back into the patient. Each patient received their own cells via an injection into the knee. The patients were split into four groups with each receiving a different number of cells. The patients were monitored for up to two years after injection.

Stem cell therapy is safe for knee osteoarthritis

The scientists found that the stem cell injections were safe, there were no serious side effects and only four of the patients suffered pain or swelling at the injection site which cleared without intervention. The scientist asked the patients to report on their perceived pain and they were able to show a significant improvement after treatment. This study does not account for the placebo effect, however, as the scientist did not include a cell-free control group. This makes it difficult to determine whether the improvement in pain management was genuine.

The researchers also used magnetic resonance images (MRI) of the knee and found no improvements to the cartilage after 12 months. The researchers then screened blood and urine to detect molecules associated with chondrocyte degradation. The level of these molecules remained constant over one year indicating that the stem cells may have a protective effect on the chondrocytes. The scientists also found a decrease in pro-inflammatory markers present in the knee. This suggests that the stem cells may suppress the immune responses in this tissue. Although the data presented in this study are intriguing, only twelve patients were observed. This small sample size makes it difficult to draw relevant conclusions about the broader population.

The important findings of this work are that the use of mesenchymal stromal cells is safe and tolerable treatment for knee osteoarthritis in patients. “This sets the stage for the future of cell-based therapy and trials in Canada,” said Dr. Chahal, the lead author of this study. This work paves the way for larger clinical trials that will produce stronger evidence for their current findings.


  1. Wolfstadt JI, Cole BJ, Ogilvie-Harris DJ, Viswanathan S, Chahal J. Current concepts: the role of mesenchymal stem cells in the management of knee osteoarthritis. Sports Health. 2015;7(1):38-44. doi:10.1177/1941738114529727

2. Uth K, Trifonov D. Stem cell application for osteoarthritis in the knee joint: A mini review. World J Stem Cells. 2014;6(5):629-636. doi:10.4252/wjsc.v6.i5.629

3. Ruiz M, Cosenza S, Maumus M, Jorgensen C, Noël D. Therapeutic application of mesenchymal stem cells in osteoarthritis. Expert Opin Biol Ther. 2016;16(1):33-42. doi:10.1517/14712598.2016.1093108

4. Pers YM, Ruiz M, Noël D, Jorgensen C. Mesenchymal stem cells for the management of inflammation in osteoarthritis: state of the art and perspectives. Osteoarthritis Cartilage. 2015;23(11):2027-2035. doi:10.1016/j.joca.2015.07.004

5. Britannica, T. Editors of Encyclopaedia. 2022, November 18. Blood cell formation. Encyclopedia Britannica.

6. Chahal J, Gómez-Aristizábal A, Shestopaloff K, et al. Bone Marrow Mesenchymal Stromal Cell Treatment in Patients with Osteoarthritis Results in Overall Improvement in Pain and Symptoms and Reduces Synovial Inflammation. Stem Cells Transl Med. 2019;8(8):746-757. doi:10.1002/sctm.18-0183

7. Sherman H. Stem cell trial for osteoarthritis patients reduces pain, improves quality of life. EurekAlert! April 12, 2019.

Tarryn Bourhill MSc PhD Candidate
Tarryn Bourhill MSc PhD Candidate
Tarryn has a Master’s degree in Molecular Medicine from the University of the Witwatersrand, South Africa. She is currently pursuing a PhD in Molecular Biology and Biochemistry at the University of Calgary. Tarryn specializes in cancer, oncolytic viral therapy and stem cell research. She is passionate about scientific communication and enjoys turning complicated ideas into approachable and engaging conversations. In her spare time, Tarryn is a keen baker and a photography enthusiast.


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