BME Seminar Series: Dr. Duncan Maitland, Texas A&M
"Embolic Applications of Shape Memory Polymer Foams"
We have developed a platform material for embolic medical applications: shape memory polymer (SMP) foams. The SMP implants include a passively actuated open-celled foam that expands to rapidly fill and occlude blood vessels and blood vessel malformations (e.g. aneurysms). The foams enable more of the vessel/aneurysm volume to be filled with a high surface area foreign body that encourages more rapid and complete acute clotting. Chronically, the foams result in the recruitment of connective tissue by forming collagenous scars.
The SMP materials are aliphatic, amorphous highly crosslinked polyurethane (urea). Foams are formed using chemical and physical blowing agents. The thermo-mechanical properties of the foams can be tuned by varying the di-isocyanate (NCO) and alcohol (OH) monomers to suite the clinical need. We typically use materials that passively actuate in the body due to plasticization of the polyurethane when exposed to blood (water). These materials can be designed to actuate within minutes to many hours at body temperature. The SMP foams are biodegradable over multiple-year timescales due to oxdatively labile amine linkages in the OH monomers. The degradation timescale for our materials are significantly longer than their functional lifetime. The degradation products have shown to be non-toxic and biocompatible. Biodurable versions of the chemistry are also available via replacing the amine-containing monomers.
This talk will present the rational for pursuing embolic scaffolds, background material and device properties, benchtop and in vivo study results and discuss the tradeoffs of conducting this work in an academic setting and translating the technology to industry. After 20 years of research the first in human implantation of a peripheral occlusion device based on the SMP foams occurred on August 1, 2017. Clinical and commercial plans for the technology will also be covered.
Dr. Maitland has worked as an engineer in aerospace, national defense and biomedical applications since 1985. He received his B.E.E. (Electrical Engineering) and M.S. (Physics) degrees from Cleveland State University. He received his Ph.D. in Biomedical Engineering from Northwestern University. After his Ph.D., he worked at Lawrence Livermore National Laboratory for thirteen years before joining Texas A&M University in 2008. His research focuses on novel treatments of cardiovascular disease with a focus on stroke. Research projects include endovascular interventional devices, microactuators, optical therapeutic devices and basic device-body interactions/physics including computational and experimental techniques. He has over 90 archival publications, 24 issued patents and multiple recent awards for entrepreneurship. His current focus is the commercial translation of porous shape memory polymer (polyurethane) medical devices.