Study characteristics and quality assessment
UC
Four studies were included in this systematic review, three were RCTs, and one was non-RCTs. The included studies involved a total of 358 patients. The studies of Wang et al. (2013) and Yang et al. (2018) were conducted in China, Álvaro-Gracia et al. (2017) in Spain, and Shadmanfar et al. (2018) was conducted in Iran; only one study was multi-center (Álvaro-Gracia et al.). The study of Álvaro-Gracia et al. (2017) was divided into three subgroups according to the dosage, and the study of Yang et al. 2018 was divided into two subgroups according to the response or non-response of MSCs treatment, the route of administration was intravenous for 75% of the studies and intra-articular for 25% of these. The tissue sources of MSCs were: 50% umbilical cord (UC), 25% bone marrow (BM), and 25% adipose tissue (AT). Finally, the treatment assignments were masked in 50% of the studies. The included studies’ overall characteristics are shown in 