A recent clinical study explored the effects of injecting moderately osteoarthritic knees with a single dose of a mixed population of bone-marrow-derived cells. This mix of bone marrow-derived cells (bone marrow-derived mononuclear cells/BM MNCs) each have one nucleus and include blood progenitor cells, immune system cells, and stem cells that can become a variety of musculoskeletal cell types. Subjects of this study included thirty-two middle-aged subjects (sixteen male and sixteen female), and a total of thirty-four knees were treated. A year post-treatment, 65% of patients retained improvement in the Knee Injury and Osteoarthritis Outcome Score(KOOS), which is a patient-reported questionnaire on the severity of symptoms and function. Moreover, there was an overall improvement in symptoms and function validated by the KOOS and KSS scores in addition to tissue structure which was confirmed by Magnetic Resonance Imaging(MRI) studies and there were no adverse effects to the treatment. This study concluded that a single dose of BM MNC could partially reduce signs of moderate (stage II/III) osteoarthritis and in some cases can reduce degenerative changes in the joint over the span of a year. More studies are needed to better understand how bone marrow derived cells can help patients with degenerative joint disease and arthritis.