Bone Marrow-Derived Mesenchymal Stem Cells Alleviate Cutaneous Leishmaniasis by Promoting M2 Macrophage Polarization...

Cutaneous leishmaniasis (CL) is the most common clinical form of leishmaniasis, characterized by persistent skin ulcers and nodules. Standard chemotherapeutic agents have substantial toxicity and do nothing to repair the damaged tissue, an unmet need that motivates the search for adjunctive strategies. Mesenchymal stem cells (MSCs) can modulate macrophage activity and support tissue regeneration, yet their role in CL has received limited attention. In this study, we tested whether bone marrow-derived MSCs (BM-MSCs) could attenuate Leishmania mexicana-induced inflammation and facilitate skin repair. Indirect co-culture of BM-MSCs with infected RAW264.7 macrophages shifted the macrophage phenotype from M1 toward M2, with higher IL-10 and Arg-1 expression and lower iNOS and IL-1β. In BALB/c mice with established CL, three weekly intravenous injections of BM-MSCs reduced paw swelling, improved skin histology, decreased type I collagen deposition, lowered Integrin β1 and Cytokeratin 17 expression, and reduced tissue parasite load. Immunofluorescence confirmed a predominantly M2 macrophage distribution in treated lesions. We inferred that BM-MSCs acted on both the immune and reparative aspects of the disease process, supporting their potential as an adjunct to conventional anti-leishmanial therapy.