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Aneurysm wall cellularity affects healing after coil embolization: assessment in a rat saccular aneurysm model
  1. Edin Nevzati1,
  2. Jeannine Rey1,
  3. Daniel Coluccia1,
  4. Basil Erwin Grüter1,2,
  5. Stefan Wanderer1,2,
  6. Michael vonGunten3,
  7. Luca Remonda4,
  8. Juhana Frosen5,
  9. Hans Rudolf Widmer6,
  10. Javier Fandino1,2,
  11. Serge Marbacher1,2
  1. 1Department for Biomedical Research (DBMR), University of Bern, Cerebrovascular Research Group, Bern, Switzerland
  2. 2Department of Neurosurgery, Kantonsspital Aarau, Aarau, Switzerland
  3. 3Institute of Pathology Laenggasse, Ittigen, Switzerland
  4. 4Division of Neuroradiology, Department of Radiology, Kantonsspital Aarau, Aarau, Switzerland
  5. 5Hemorrhagic Brain Pathology Research Group, Kuopio University Hospital, Kuopio, Finland
  6. 6Neurocenter and Regenerative Neuroscience Cluster, Inselspital, University Hospital and University of Bern, Bern, Switzerland
  1. Correspondence to Dr Edin Nevzati, Department for Biomedical Research (DBMR), University of Bern, 3012 Bern, Switzerland; edin.nevzati{at}


Background and purpose Despite significant technical advances, recanalization rates after endovascular therapy of ruptured intracranial aneurysms (IAs) remain a clinical challenge. A histopathological hallmark of ruptured human IA walls is mural cell loss. Mural smooth muscle cells (SMCs) are known to promote intraluminal healing in thrombosed experimental aneurysms. In this rat model we assess the natural history and healing process after coil embolization in SMC-rich and decellularized aneurysms.

Methods Saccular aneurysms were created by end-to-side anastomosis of an arterial graft from the descending thoracic aorta of a syngeneic donor rat to the infrarenal abdominal aorta of recipient male Wistar rats. Untreated arterial grafts were immediately transplanted, whereas aneurysms with loss of mural cells were chemically decellularized before implantation. Aneurysms underwent coil implantation during aneurysm anastomosis. Animals were randomly assigned either to the non-decellularized or decellularized group and underwent macroscopic and histological analyses on days 3, 7, 21, or 90 post-coil implantation.

Results A total of 55 rats underwent macroscopic and histologic analysis. After coil embolization, aneurysms with SMC-rich walls showed a linear course of thrombosis and neointima formation whereas decellularized aneurysms showed marked inflammatory wall degeneration with increased recanalization rates 21 days (p=0.002) and 90 days (p=0.037) later. The SMCs showed the ability to actively migrate into the intra-aneurysmal thrombus and participate in thrombus organization.

Conclusions Coil embolization of aneurysms with highly degenerated walls is prone to further wall degeneration, increased inflammation, and recanalization compared with aneurysms with vital SMC-rich walls.

  • aneurysm
  • coil
  • vessel wall
  • inflammation

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  • Contributors All authors made a substantial contribution to the concept and design or analysis and interpretation of data, drafting or critical revision of the manuscript, and final approval of the submitted version of the manuscript.

  • Funding This work was supported by a research grant from the Research Council of the Kantonsspital Aarau, grant number 1410.000.05.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available upon reasonable request. All data relevant to the study are included in the article or uploaded as supplementary information.