Therapeutic benefit of bone marrow-derived endothelial progenitor cell transplantation after experimental aneurysm embolization with coil in rats.

Aneurysm embolization with coil is now widely used clinically. However, the recurrence of aneurysms after embolization has always plagued neurosurgeons because the endothelial layer of the aneurysm neck loses its integrity after being embolized by coil. Bone marrow-derived endothelial progenitor cells (BM-EPCs) could be incorporated into injured endothelium and differentiate into mature endothelial cells during vascular repairing processes. The aim of our study is to explore the effects of BM-EPCs on aneurysm repairing and remodeling in a rat embolization model of abdominal aortic aneurysm. BM-EPC proliferation, migration and tube formation were not affected by super-paramagnetic iron oxide nanoparticle (SPIO) labeling compared to the controls (p>0.05). The number of SPIO-labeled cells greatly increased in EPC transplanted rats compared to that of phosphate buffered saline treated rats. SPIO-labeled EPC (SPIO-EPC) are mainly located in the aneurysm neck and surrounded by fibrous tissue. A histology study showed that the aneurysm orifice was closed with neointima and the aneurysm was filled with newly formed fibrous tissue. The SPIO-EPC accumulated in the aneurysm neck, which accelerated focal fibrous tissue remodeling, suggesting that BM-EPCs play a crucial role in repairing and remodeling the aneurysm neck orifice.