Amelioration of diabetic nephropathy in mice by a single intravenous injection of human mesenchymal stromal cells at early and later disease stages is associated with restoration of autophagy

• Single intravenous injection of human umbilical cord-derived MSCs ameliorates diabetic nephropathy in mice at both early and later disease stages, without affecting hyperglycemia. • Reno-protective effects are associated with reduced circulating TGF-β1 and restoration of intra-renal autophagy. • Early MSC treatment reduces serum IL-6 and TNF-α, while later treatment does not, suggesting differential anti-inflammatory effects. • MSCs persist in kidneys, lungs, and liver for at least 14 days post-injection, supporting their potential for targeted therapy.