Basic fibroblast growth factor released from a platinum coil with a polyvinyl alcohol core enhances cellular proliferation and vascular wall thickness: An in vitro and in vivo study

OBJECTIVE: We developed a new type of platinum coil that has a polyvinyl alcohol (PVA) core to absorb and release various biologically active materials for the endovascular treatment of intracranial aneurysms. We evaluated its efficacy as an embolic material with basic fibroblast growth factor (bFGF) in an in vitro and in vivo study. METHODS: A small PVA thread was inserted into the central space of the primary coil. This coil was named the PVA-core coil. Ten-millimeter segments of the PVA-core coil were used in this study. PVA-core coils were immersed in a bFGF solution for 1 hour. The PVA-core coil, which absorbed bFGF in the PVA-core, was named the FGF-core coil. Initially, the dose of bFGF released from the PVA core into saline was measured by performing an enzyme-linked immunosorbent assay. In the in vitro study, FGF-core coils, PVA-core coils, and unmodified coils were cultured with fibroblasts (NIH3T3), and then their surfaces were observed with electron microscopy. In the in vivo study, each coil was implanted into a rat common carotid artery. The rats were killed, and the arterial lumen was histologically examined at 14 and 28 days after coil implantation. RESULTS: BFGF was released from the PVA core into saline within 24 hours by performing an enzyme-linked immunosorbent assay. Electron microscopic findings demonstrated remarkable cellular adhesion to the surfaces of the FGF-core coils, but no adhesion to the surfaces of the PVA-core coils and the unmodified coils was found. Histologically, remarkable cell proliferation in the vascular lumen was demonstrated in the common carotid arteries of the FGF-core coil implantation group at the 14th and 28th days. Cellular components proliferated around the implanted coil, and these components mainly stained blue with Masson trichrome. These changes did not occur in the PVA-core coil group and the unmodified coil group. CONCLUSION: We suggest that FGF-core coils may be effective in inducing fibrotic changes inside aneurysms. These coils may be used as an embolic material to cure cerebral aneurysms.