Stem Cell Treatment for Knee Articular Cartilage Defects and Osteoarthritis

To review the current basic science and clinical literature on mesenchymal stem cell (MSC) therapy for articular cartilage defects and osteoarthritis of the knee. MSCs derived from bone marrow, adipose, and umbilical tissue have the capacity for self-renewal and differentiation into the chondrocyte lineage. In theory, MSC therapy may help restore cartilage focally or diffusely where nascent regenerative potential in the intra-articular environment is limited. Over the last several years, in vitro and animal studies have elucidated the use of MSCs in isolation as injectables, in combination with biological delivery media and scaffolding, and as surgical adjuvants for cartilage regeneration and treatment of knee degenerative conditions. More recently, clinical and translational literature has grown more convincing from early descriptive case series to randomized controlled trials showing promise in efficacy and safety. Studies describing MSC for knee cartilage regeneration applications are numerous and varied in quality. Future research directions should include work on elucidating optimal cell concentration and dosing, as well as standardization in methodology and reporting in prospective trials. Backed by promise from in vitro and animal studies, preliminary clinical evidence on MSC therapy shows promise as a nonoperative therapeutic option or an adjuvant to existing surgical cartilage restoration techniques. While higher quality evidence to support MSC therapy has emerged over the last several years, further refinement of methodology will be necessary to support its routine clinical use.