Using Mesenchymal Stem Cells to Treat Cartilage Defects

Most large joints of the body contain cartilage, a substance that is softer and more flexible than bone. Because of its softness and flexibility, cartilage is well-suited to protect the bones as they move across one another. Unfortunately, this softness and flexibility also makes cartilage prone to injury and erosion. In patients with osteoarthritis, forexample, cartilage breaks down to the point that bone rubs against bone,causing pain and disability. Certain injuries can damage the cartilage (i.e.osteochondral lesion), which can essentially have the same effect.

Once the cartilage of joints has become damaged, there is little that can be done to fix it. Patients may receive steroid injections into the joint to reduce inflammation, and may rely on pain medications to relieve the pain and swelling. Short of joint replacement therapy, no treatments can reverse cartilage damage once it has occurred.

Fortunately, mesenchymal stem cells may soon be able to reverse cartilage defects that arise from osteochondral lesions and osteoarthritis. Wakitani and colleagues took samples of patients’ bone marrow, which contains mesenchymal stem cells. They then used various laboratory techniques to increase the number of stem cells in the sample. Four weekslater, the researchers then reinjected the concentrated stem cells back intothe same patient using their own source of stem cells. The Wakitani groupshowed that stem cell transplantation improved the patient’s clinical symptoms bysix months, a benefit that continued for two years on average. Samples takenfrom the patients 12 months later showed that the damaged cartilage had beenrepaired. In other work, Centeno and co-authors showed that bone marrow-derived mesenchymal stemcells could increase the volume of cartilage, reduce pain, and increase rangeof motion 24 weeks after stem cell transplantation.

Research continues to determine which stem cells are most useful, how many stem cells should be injected, how many injections need to be administered, and how should those stem cells be prepared before they are injected? Nonetheless, certain groups are making great strides in this area. In fact, the recent discovery of human skeletal stem cells promises to accelerate stem cell research into treating disorders of bone and cartilage.

Reference

Schmitt et al. (2012). Application of Stem Cells in Orthopedics. Stem Cells International. 2012: 394962