Bone marrow aspiration and subsequent cell preparation were accomplished on the same day as the endovascular infusion of autologous Bone Marrow derived Mononuclear stem cells (BMDMCs) in both renal arteries. Collection was performed under spinal anesthesia and light sedation, through puncture and repeated aspirations at the posterior iliac crest region. A total of 80 mL of bone marrow aspirate was collected from each patient, and after removal of bone and fatty residues, mononuclear cells were isolated by a Ficoll-Paque Plus (Amersham Biosciences, São Paulo, Brazil).For each patient, 2×107 cells will be labeled with 99mTc. Briefly, 500 μl of sterile SnCl2 solution is added to the cells and the mixture is incubated at room temperature for 10 min. Forty-five millicurie (mCi) of 99mTc is then added and incubation continued for another 10 min. After centrifugation (500×g for 5 min), the supernatant is removed and the cells are washed in saline solution. The pellet will be also resuspended in saline solution. Viability of the labeled cells will be assessed by the trypan blue exclusion test, and estimated to be greater than 93% in all cases.The labeling efficiency (%) will be calculated by the activity in the pellet divided by the sum of the radioactivity in the pellet plus supernatant and estimated to be greater than 90% in all cases.