Shape Memory Polymer Devices for Treating Stroke

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DESCRIPTION (provided by applicant): We propose to develop interventional devices for treating stroke victims that currently have no therapeutic alternatives (.400,000/yr in the USA). The development and testing of two complementary devices is proposed: a mechanical clot extraction system and a neurovascular stent. The clot extraction system will address the current clinical need for an acute ischemic stroke treatment and the stent will address the chronic problem of stenosis and/or restenosis of the neurovasculature. Both of these devices utilize photomechanica' micro-actuators based on laser-activated shape memory polymer (SMP). SMP is a material that will have a significant impact on clinical medicine. SMP is a relatively new material that is similar to shape memory metals in its ability to actuate from an initial deformed shape into a second, pre-determined shape. Shape memory metals are currently very popular in medicine as a material for making vascular stents. SMP has advantages over shape memory metals for certain applications, including cost, higher recoverable strain levels, ease of manufacturing, better flexibility in navigating tortuous paths, and great versatility in fabricating extremely small, highly complex actuators. Potential applications of SMP include stents, stent release mechanisms, embolic coil release mechanisms, thrombus extraction devices, and many others. The underlying hypothesis of this research is that mechanical devices can be used to treat stroke victims where there is currently no clinical alternative. There are five known private companies that are currently pursuing this hypothesis for the acute ischemic device and an unknown but presumed large number of companies pursuing neurovascular stents. Members of the current proposal team originally developed one of the technologies that are in FDA trials for treating ischemic stroke, photo-acoustic emulsification of the thrombus. However, in our opinion, none of the current devices under FDA trials is as promising or as straightforward as the devices proposed. Further, we believe that the technology developed and published from the proposed studies will lead to many other medical applications that are far beyond the scope of one proposal and one team of investigators. The proposed research is a unique combination of biomaterials, lasers and optics, immunology/biocompatibility and clinical interventional neuroradiology. The long-term goal of this research is to deliver clinical prototype devices that can begin FDA clinical trials.