Normothermic machine perfusion (NMP) of injured kidneys offers the opportunity for interventions to metabolically active organs prior to transplantation. Mesenchymal stromal cells (MSCs) can exert regenerative and anti-inflammatory effects in ischaemia-reperfusion injury. The aims of this study were to evaluate the safety and feasibility of MSC treatment of kidneys during NMP using a porcine auto-transplantation model, and examine potential MSC treatment-associated kidney improvements up to 14 days post transplantation. After 75 minutes of kidney warm ischaemia, four experimental groups of n=7 underwent 14 hours of oxygenated hypothermic machine perfusion. In three groups this was followed by 240 minutes of NMP with infusion of vehicle, ten million porcine or ten million human adipose derived MSCs. All kidneys were auto-transplanted after contralateral nephrectomy. MSC treatment did not affect perfusion haemodynamics during NMP or cause adverse effects at reperfusion, with 100% animal survival. MSCs did not affect plasma creatinine, glomerular filtration rate, neutrophil gelatinase-associated lipocalin concentrations or kidney damage assessed by histology during the 14 days, and MSCs retention was demonstrated in renal cortex. Infusing MSCs during ex vivo NMP of porcine kidneys was safe and feasible. Within the short post- transplant.