Institute of Pathology Laenggasse 1 article published in JoVE Neuroscience Using a Cell-Tracer Injection to Investigate the Origin of Neointima-Forming Cells in a Rat Saccular Side Wall Model Stefan Wanderer*1,2, Basil E. Grüter*1,2, Jeannine Kümin1,2, Gwendoline Boillat1,2, Sivani Sivanrupan2, Kristina Catalano1,2, Michael von Gunten3, Hans Rudolf Widmer4, Serge Marbacher1,2,5, Lukas Andereggen1,2,5 1Department of Neurosurgery, Kantonsspital Aarau, 2Cerebrovascular Research Group, Department for BioMedical Research, University of Bern, 3Institute of Pathology Laenggasse, 4Department of Neurosurgery, Neurocenter and Regenerative Neuroscience Cluster, Inselspital, Bern University Hospital, University of Bern, 5Faculty of Medicine, University of Bern We performed a one-point, lipophilic cell-tracer injection to track endothelial cells, followed by an arteriotomy and suturing of sidewall aneurysms on the abdominal rat aorta. Neointima formation seemed dependent on the parent artery in decellularized aneurysms and was promoted by the recruitment from aneurysm wall cells in vital cell-rich walls.