Shape Memory Polymer Foam With Tunable Properties for Treatment of Intracranial Aneurysm

2020 ◽  
Author(s):  
Sergio A. Pineda-Castillo ◽  
Jishan Luo ◽  
Bradley N. Bohnstedt ◽  
Chung-Hao Lee ◽  
Yingtao Liu
Keyword(s):  
Shape Memory ◽  
Intracranial Aneurysms ◽  
Shape Memory Polymer ◽  
Specific Treatment ◽  
Mass Effect ◽  
Patient Specific ◽  
Polymer Foam ◽  
Composite Foams ◽  
Incomplete Occlusion

Abstract Intracranial aneurysms have the potential to be fatal; when detected, they must be treated promptly by surgical clipping or by endovascular methods. The latter, while having better long-term overall survival than the former, fail to provide complete occlusion of the aneurysm lumen, creating risks for therapy-related adverse events, such as embolic device migration or recanalization. Polyurethane shape memory polymers (SMPs) have the potential to provide patient-specific treatment to reduce rates of incomplete occlusion and mass effect. In this study, SMP matrices are infiltrated with carbon nanotubes (CNTs) to induce electrical conductivity and provide a precise triggering method for deployment of the embolic device. Through thermomechanical characterization of the composite, it was determined that CNTs play a significant role in resistivity of the SMP foam and its ultimate shape recovery properties. Cyclic mechanical testing allowed to determine that CNTs might induce polymeric matrix damage, creating the need for new approaches to CNT infiltration. The studied composite foams were able to occlude an in vitro idealized aneurysm phantom model, which allowed to conclude that the proposed CNT-infiltrated SMP foams exhibit potential as biomedical devices for endovascular therapy of intracranial aneurysms.

Synthesis and Characterization of Radiopaque Shape Memory Polymers

2017 ◽  
Author(s):  
Kendal Ezell ◽  
Landon Nash ◽  
Sonya Gordon ◽  
Duncan Maitland
Keyword(s):  
Shape Memory ◽  
Shape Memory Polymer ◽  
The United States ◽  
Endovascular Embolization ◽  
Polymer Foam ◽  
X Ray ◽  
Unruptured Cerebral Aneurysm ◽  
Composite Foams ◽  
Function Impairment

An estimated 6 million people in the United States have an unruptured cerebral aneurysm [1]. If left untreated, these aneurysms can rupture and to lead to severe brain function impairment or even death. Shape memory polymer (SMP) foams have been proposed for use to optimize endovascular embolization in place of current embolization devices [2,3]. SMPs are capable of actuating from a programmed secondary geometry to their expanded primary geometry in response to a stimulus, such as body temperature [4]. The expanded foam geometry provides an interface for embolization of the aneurysm to occur, however, treatment with these devices has limited visibility under fluoroscopy. Previous work by Hasan et al. increased radiopacity through the incorporation of tungsten (W) nanoparticles. These composite foams showed successful x-ray visibility, but aggregate disruption of the SMP matrix led to decreased mechanical properties [5]. This work addresses limitations of composite SMP foams, namely toughness, by chemically incorporating x-ray visible monomers, such as the triodobenzene containing monomer, 5-Amino-2,4,6-triiodoisophthalic acid (AT), into the material composition. These materials enable contrast agent loading without disrupting the polymer matrix. This polymer foam system was characterized to determine the clinical relevance of the improved radiopaque SMP foam for occlusion devices.

scholarly journals In vitro performance of a shape memory polymer foam-coated coil embolization device

2017 ◽  
Vol 49 ◽  
pp. 56-62 ◽  
Author(s):  
Anthony J. Boyle ◽  
Mark A. Wierzbicki ◽  
Scott Herting ◽  
Andrew C. Weems ◽  
Adam Nathan ◽  
...  
Keyword(s):  
Shape Memory ◽  
Coil Embolization ◽  
Shape Memory Polymer ◽  
Polymer Foam ◽  
Shape Memory Polymer Foam ◽  
In Vitro Performance

scholarly journals Shape Memory Polymer Foams Synthesized Using Glycerol and Hexanetriol for Enhanced Degradation Resistance

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2290
Author(s):  
Sayyeda Marziya Hasan ◽  
Grace K. Fletcher ◽  
Mary Beth Browning Monroe ◽  
Mark A. Wierzbicki ◽  
Landon D. Nash ◽  
...  
Keyword(s):  
Shape Memory ◽  
Shape Memory Polymer ◽  
Polymer System ◽  
Vascular Occlusion ◽  
Superior Performance ◽  
Polymer Foams ◽  
Polymer Foam ◽  
Shape Memory Behavior ◽  
Wide Range

Shape memory polymer foams have been used in a wide range of medical applications, including, but not limited to, vessel occlusion and aneurysm treatment. This unique polymer system has been proven to shape-fill a void, which makes it useful for occlusion applications. While the shape memory polymer foam has superior performance and healing outcomes compared to its leading competitors, some device applications may benefit from longer material degradation times, or degradation-resistant formulations with increased fibrous encapsulation. In this study, biostable shape memory polymer foams were synthesized, and their physical and chemical properties were characterized as an initial evaluation of feasibility for vascular occlusion applications. After characterizing their shape memory behavior in an aqueous environment, degradation of this polymer system was studied in vitro using accelerated oxidative and hydrolytic solutions. Results indicated that the foams did not lose mass under oxidative or hydrolytic conditions, and they maintained high shape recovery in aqueous in vitro models. These degradation-resistant systems have potential for use in vascular occlusion and other wound healing applications that benefit from permanent, space-filling shape memory behavior.

Characterization of shape memory polymer foam hemostats in in vitro hemorrhagic wound models

2020 ◽  
Author(s):  
Nakira Christmas ◽  
Anand Utpal Vakil ◽  
Christopher J. Hatch ◽  
Shi Dong ◽  
David Fikhman ◽  
...  
Keyword(s):  
Shape Memory ◽  
Shape Memory Polymer ◽  
Polymer Foam ◽  
Shape Memory Polymer Foam

scholarly journals Enhanced X-ray Visibility of Shape Memory Polymer Foam Using Iodine Motifs and Tantalum Microparticles

2021 ◽  
Vol 5 (1) ◽  
pp. 14
Author(s):  
Lindy K. Jang ◽  
Landon D. Nash ◽  
Grace K. Fletcher ◽  
Thomas Cheung ◽  
Andrew Soewito ◽  
...  
Keyword(s):  
Shape Memory ◽  
Shape Memory Polymer ◽  
High Surface ◽  
High Surface Area ◽  
Polymer Foam ◽  
Brain Aneurysm ◽  
X Ray ◽  
Safe Delivery ◽  
Aneurysm Embolization

Shape memory polymer (SMP) foams are porous materials with high surface area and large volumetric expansion capabilities that are well suited for endovascular occlusion applications, including brain aneurysm embolization. However, many polyurethane SMP foams are inherently radiolucent when X-ray visibility is required to ensure the safe delivery of the foam to the targeted aneurysm site using fluoroscopy. Here, highly radio-dense tantalum microparticles were added to a previously reported triiodobenzene-containing SMP foam (ATIPA foam) premix to fabricate ATIPA foam-tantalum composites (AT_T). The AT_T foams showed comparable glass transition temperatures, faster expansion profiles, increased X-ray visibility, good cytocompatibility, and faster oxidative degradation compared to the control ATIPA foam without tantalum. The mechanical properties were improved up to 4 vol% tantalum and the X-ray visibility was most appropriate for the 2 vol% (AT_2%T) and 4 vol% (AT_4%T) tantalum foams. E-beam sterilization did not impair the critical properties of the ATIPA foams. Overall, AT_2%T was the optimal foam composition for neurovascular prototypes due to its high oxidative stability in vitro compared to previous low-density SMP foams. The AT_T foams are very promising materials with high toughness and sufficient X-ray visibility for use as neurovascular embolization devices.

scholarly journals Opacification of Shape Memory Polymer Foam Designed for Treatment of Intracranial Aneurysms

2011 ◽  
Vol 40 (4) ◽  
pp. 883-897 ◽  
Author(s):  
Jennifer N. Rodriguez ◽  
Ya-Jen Yu ◽  
Matthew W. Miller ◽  
Thomas S. Wilson ◽  
Jonathan Hartman ◽  
...  
Keyword(s):  
Shape Memory ◽  
Intracranial Aneurysms ◽  
Shape Memory Polymer ◽  
Polymer Foam ◽  
Shape Memory Polymer Foam

scholarly journals Modeling glioblastoma invasion using human brain organoids and single-cell transcriptomics

2019 ◽  
Author(s):  
Teresa G Krieger ◽  
Stephan M Tirier ◽  
Jeongbin Park ◽  
Tanja Eisemann ◽  
Heike Peterziel ◽  
...  
Keyword(s):  
Single Cell ◽  
Specific Treatment ◽  
Cellular Heterogeneity ◽  
Patient Specific ◽  
Before And After ◽  
Invasive Capacity ◽  
Transcriptional Changes ◽  
Potential Interactions

AbstractGlioblastoma multiforme (GBM) are devastating neoplasms with high invasive capacity. GBM has been difficult to study in vitro. Therapeutic progress is also limited by cellular heterogeneity within and between tumors. To address these challenges, we present an experimental model using human cerebral organoids as a scaffold for patient-derived glioblastoma cell invasion. By tissue clearing and confocal microscopy, we show that tumor cells within organoids extend a network of long microtubes, recapitulating the in vivo behavior of GBM. Single-cell RNA-seq of GBM cells before and after co-culture with organoid cells reveals transcriptional changes implicated in the invasion process that are coherent across patient samples, indicating that GBM cells reactively upregulate genes required for their dispersion. Functional therapeutic targets are identified by an in silico receptor-ligand pairing screen detecting potential interactions between GBM and organoid cells. Taken together, our model has proven useful for studying GBM invasion and transcriptional heterogeneity in vitro, with applications for both pharmacological screens and patient-specific treatment selection at a time scale amenable to clinical practice.

Deformation of epoxy shape memory polymer foam. Part I: Experiments and macroscale constitutive modeling

2010 ◽  
Vol 42 (3) ◽  
pp. 304-314 ◽  
Author(s):  
M. Di Prima ◽  
K. Gall ◽  
D.L. McDowell ◽  
R. Guldberg ◽  
A. Lin ◽  
...  
Keyword(s):  
Shape Memory ◽  
Constitutive Modeling ◽  
Shape Memory Polymer ◽  
Polymer Foam ◽  
Shape Memory Polymer Foam

Lagrangian Trajectory Simulation of Platelets and Synchrotron Microtomography Augment Hemodynamic Analysis of Intracranial Aneurysms Treated With Embolic Coils

2021 ◽  
Vol 143 (7) ◽  
Author(s):  
Venkat Keshav Chivukula ◽  
Laurel Marsh ◽  
Fanette Chassagne ◽  
Michael C. Barbour ◽  
Cory M. Kelly ◽  
...  
Keyword(s):  
Shear Stress ◽  
Treatment Outcomes ◽  
Intracranial Aneurysms ◽  
Thrombus Formation ◽  
Vascular Wall ◽  
Cfd Modeling ◽  
Patient Specific ◽  
Embolic Coils ◽  
Endovascular Coils

Abstract As frequency of endovascular treatments for intracranial aneurysms increases, there is a growing need to understand the mechanisms for coil embolization failure. Computational fluid dynamics (CFD) modeling often simplifies modeling the endovascular coils as a homogeneous porous medium (PM), and focuses on the vascular wall endothelium, not considering the biomechanical environment of platelets. These assumptions limit the accuracy of computations for treatment predictions. We present a rigorous analysis using X-ray microtomographic imaging of the coils and a combination of Lagrangian (platelet) and Eulerian (endothelium) metrics. Four patient-specific, anatomically accurate in vitro flow phantoms of aneurysms are treated with the same patient-specific endovascular coils. Synchrotron tomography scans of the coil mass morphology are obtained. Aneurysmal hemodynamics are computationally simulated before and after coiling, using patient-specific velocity/pressure measurements. For each patient, we analyze the trajectories of thousands of platelets during several cardiac cycles, and calculate residence times (RTs) and shear exposure, relevant to thrombus formation. We quantify the inconsistencies of the PM approach, comparing them with coil-resolved (CR) simulations, showing the under- or overestimation of key hemodynamic metrics used to predict treatment outcomes. We fully characterize aneurysmal hemodynamics with converged statistics of platelet RT and shear stress history (SH), to augment the traditional wall shear stress (WSS) on the vascular endothelium. Incorporating microtomographic scans of coil morphology into hemodynamic analysis of coiled intracranial aneurysms, and augmenting traditional analysis with Lagrangian platelet metrics improves CFD predictions, and raises the potential for understanding and clinical translation of computational hemodynamics for intracranial aneurysm treatment outcomes.

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