This 2013 clinical study evaluated the safety and efficacy of human umbilical cord mesenchymal stem cells (UC-MSCs) in treating active rheumatoid arthritis (RA) unresponsive to conventional therapies. Involving 172 patients, the study compared outcomes between those receiving disease-modifying anti-rheumatic drugs (DMARDs) plus UC-MSCs and those receiving DMARDs alone. The UC-MSC
