Allogenic Umbilical Cord-Derived Mesenchymal Stromal Cells Sustain Long-Term Therapeutic Efficacy Compared With Low-Dose Interleukin-2 in Systemic Lupus Erythematosus

OBJECTIVES: Mesenchymal stromal cells (MSCs) and low-dose interleukin-2 (IL-2) both have demonstrated efficacy in treating systemic lupus erythematosus (SLE). The aim of this study is to conduct a head-to-head comparison between the 2 treatments and provide insights for clinical applications. METHODS: Lupus-prone mice were treated with umbilical cord-derived MSCs (UC-MSCs), IL-2, or a combination of UC-MSCs and IL-2, respectively. The lupus-like symptoms, renal pathology, and T-cell response were assessed 1 or 4 weeks later. Modulation of IL-2 production by MSCs on immune cells was investigated by the coculture assay. Disease activity and serum IL-2 of SLE patients were determined before and after receiving UC-MSCs. RESULTS: Both UC-MSCs and IL-2 improved lupus symptoms in lupus-prone mice 1 week after treatment, while the effects of UC-MSCs lasted up to 4 weeks. Moreover, the UC-MSC-treated group showed better renal pathology improvement. Importantly, UC-MSCs combined with IL-2 did not provide better efficacy than UC-MSCs alone. Consistent with this, UC-MSCs alone and UC-MSCs + IL-2 resulted in similar levels of serum IL-2 and frequencies of Tregs. Neutralization of IL-2 partly reduced the promotion of Tregs by UC-MSCs, suggesting that IL-2 was involved in the upregulation of Tregs by UC-MSCs. Lastly, an increase in serum IL-2 positively correlated with the reduction of disease activity of SLE patients by UC-MSCs. CONCLUSION: Both the single injection of UC-MSCs and repeated IL-2 administration exerted comparable efficacy in alleviating SLE manifestations, but UC-MSCs provided sustained alleviation and showed better improvement in renal pathology.