Intra-Articular Injections of Mesenchymal Stem Cells for Knee Osteoarthritis
Knee osteoarthritis (KOA) represents an enormous societal burden. This review article summarizes the knowledge on the efficacy of using intra-articular injections of mesenchymal stem cells (MSCs) to treat KOA.
PubMed (Medline) and the Cochrane Library were searched for literature related to MSC therapy and KOA up until January 31, 2014. The key search terms used were stem cells and knee osteoarthritis. One hundred thirty-five reports were found, but only the 25 fully focused on the topic were used for analysis.
Only 3 randomized controlled trials (level II evidence) found pain relief and functional improvement over the short term. The other human studies also reported encouraging results, but their evidence level was very low (IV).
Larger randomized controlled trials are needed to support these preliminary encouraging results. The relatively short duration of the studies is also a limitation for the technique at present.
Discussion
This review aimed to define the role of MSC therapy in the treatment of KOA. MSC therapy has yielded encouraging outcomes in experimental models of KOA.4-15 These experimental studies have suggested that MSCs can halt cartilage degeneration in KOA. So far, however, only 3 human studies with grade II evidence (randomized prospective trials) have been reported on the role of MSCs in KOA, but results of these studies have suggested that MSCs can reduce pain and improve function.16-18
Previous reviews of the literature1,2 have analyzed the role of MSC therapy in KOA. Barry and Murphy1 reported that several early-stage clinical trials, initiated or under way in 2013, were testing MSC delivery as an intra-articular injection into the knee, but optimal dose and vehicle were yet to be established. Filardo and colleagues2 reported that, despite growing interest in this biological approach to cartilage regeneration, knowledge on the topic is still preliminary, as shown by the prevalence of preclinical studies and the presence of low-quality clinical studies.
Study design weakness prevents effective comparison of the efficacy of MSC therapy with that of other treatments for relief of pain and other outcomes in KOA. The consistency of evidence of the clinical studies is low because of many uncontrolled variables.1-3
Conclusion
The results of MSC therapy in KOA are encouraging. However, optimal dose and vehicle are yet to be established.1 Knowledge on this topic is still preliminary. Many aspects have to be optimized, and further randomized controlled trials are needed to support the potential of this biological treatment for cartilage repair and to evaluate advantages and disadvantages with respect to the available treatments. The relative short duration of these studies is also a limitation for the technique at present.
