Healing of experimental aneurysms - II: Platelet extracts can increase thethickness of the neointima at the neck of treated aneurysms

Purpose To assess the effect of platelet extracts (PE) on neointima formation follo wing gelfoam packing of experimental porcine aneurysms. A strategy involvin g the local delivery of platelet growth factors may potentially improve lon g term results of endovascular treatment of aneurysms. Methods Bilateral lateral wall common carotid aneurysms were constructed on 30 pigs . A collagen sponge containing a PE rich in growth factors was used to pack one aneurysm with the controlateral lesion being embolized with a sponge c ontaining NaCl 0.9% (22 animals). In 8 animals, a control sponge was used o n both sides. Animals were sacrificed at 1, 2, 3, 4 and 9 weeks and the thi ckness of the neointima covering the neck of PE-treated aneurysms was measu red in 5 locations for each lesion at 2 and 3 weeks and compared with the c ontrol aneurysm of the same animal. Morphometric data was analysed using th e paired Student's t-test. Results The thickness of the neointima was significantly increased in lesions treat ed with PE as compared to control lesions at 2 weeks (p = 0.008, n = 9). Th ere was no significant difference at 3 weeks (p = 0.99, n = 9). There was n o significant difference between lesions of control animals (p = 0.95, n = 8). Conclusion PE rich in growth factors can increase the thickness of the neointima at th e neck of treated experimental porcine aneurysms at 2 weeks, but had no eff ect at 3 weeks. This accelerated neointimal formation may have some value i n improving healing following endovascular treatment. This hypothesis could not be supported with this experimental model which has a spontaneous tend ency to heal. Further studies using an animal model which reproduces the cl inical problem of recurrences may help to define the role of the local deli very of growth factors in combination with coils in a strategy designed to improve results of endovascular treatment.