Inclusion and exclusion criteria
rheumatoid arthritis, RA
RHEUMATOID ARTHRITIS, RHEUMATISM
We selected all randomized controlled trials (RCTs) or non-randomized controlled trials (non-RCTs) that met the following criteria: (i) patients > 18 years with a diagnosis of rheumatoid arthritis (RA) according to the classification criteria ACR (American College of Rheumatology) or EULAR (European League Against Rheumatism). (ii) patients with naive RA or refractory to first- or second-line treatment. (iii) studies involving mesenchymal stem cells therapy (MSCs), autologous or allogeneic, from any source (derived from BM-MSCs bone marrow; AD-MSCs adipose tissue; UC-MSCs umbilical cord; gingival, placenta, menstrual tissue) systemic or local administration. (iv) studies that include comparison groups with cell therapy (from different sources of origin or dosage), placebo, or standard therapy. (v) randomized controlled trials evaluating the efficacy and safety of mesenchymal stem cell therapy (MSC). (vi) studies conducted in the human population and published in English. Exclusion criteria were: (i) observational (analytical or descriptive) studies. (ii) studies without a control group or placebo. (iii) studies conducted on animals, children, or pregnant patients. (iv) studies without definitive results, unavailable full text, abstract of conferences, and editorial letters.