Presenting Author: Pavan Jella
A major issue in studying fetal hypoxic ischemic injury (HII) in utero in humans and its identification is limited and often the diagnosis is postponed till the post neonatal period when the injury becomes evident in neuroimaging. Hence, non-invasive imaging methods for assessing hypoxic-ischemic brain injury in-utero are of high clinical interest. Magnetic resonance (MR) susceptibility weighted imaging (SWI), can be used to measure fetal blood oxygenation that helps in assessing fetal oxygen utilization.
Thirty eight pregnant subjects (mean gestational age = 29.7±5.8) with singleton pregnancies were scanned on a 3T Siemens Verio system using modified 2D and 3D conventional SWI sequence. Due to paramagnetic nature of deoxyhemoglobin in the venous blood, SWI phase data has different magnetic susceptibility compared to the surrounding parenchyma which is dependent on its oxygen saturation. SWI data were filtered using a mild homodyne high pass filter to remove background field inhomogeneities. Mean and standard deviation of the phase within the superior sagittal sinus vessel was used to measure the venous oxygenation. The mean cerebral venous oxygen saturation measured across the 38 fetuses with mean GA 29.7±5.8 weeks was 66±10.06 %. These values are in close agreement with the fetal cerebral venous oxygen saturation, (61±14%), measured using trans-abdominal near infrared spectroscopy (NIRS) by Vintzileos et al. In summary, we have reported for the first time, in-vivo measurement of putative cerebral venous oxygen saturation in the human fetus using MRI.
Presenting Author: Eric Kim
Implantable micro-neural-probes are an important tool to study and treat various neural disorders, allowing analysis of the 3D micro-electrophysiology of the brain where current techniques fail to provide detailed information. Despite steady progress in the past a few decades, there still is a strong demand for improvements in areas such as biocompatibility and new functionality in neural probes. Here, we report the latest developments of our multifunction 3D electrode arrays using a novel, simple folding method. Thanks to an exceedingly controllable fabrication method which allows us to implement a wide variety of features, these chronic devices incorporate a variety of novel structures including trench-based parylene encapsulation and microchannel-supported flexible interconnections which significantly improve the device robustness and provide fluidic delivery and sampling at precise, controllable locations. The fabricated devices have been packaged, characterized, and implanted in the cortex of rats for up to 10 weeks. Chronic neural recordings have been successfully demonstrated with detailed neural spiking and slow-wave activity recordings specific to particular layers and columns of superficial cortical tissue. Furthermore, novel flexible neural probes based on hybrid silicon-parylene structures have been developed to reduce mechanical mismatch with the goal of improving biocompatibility, and simultaneously to eliminate the implantation difficulty of traditional polymer probes. Penetrating experiment in agarose gel has been successfully demonstrated with no observable damage to the shanks. These features in addition to others currently under development provide a versatile multifunctional micro-neural-probe platform capable of detailed micro-electrophyisiological readings and manipulation.
Presenting Author: Kevin Miles
Current regeneration techniques for cranial and maxillofacial bone injuries are inadequate. Scaffold technologies that require cell seeding and migration to fill scaffold pores fail to completely regenerate bone in vivo; an improved therapy would form the scaffold in situ, from micro-modular constructs containing stem cells. This study investigates the encapsulation of mesenchymal stem cells (MSCs) with calcium hydroxyapatite (HAP) microcarriers via ionic complexation of chondroitin 4-sulfate (C4S) with chitosan, for use as a modular bone regeneration platform. Briefly, a C4S solution containing suspended HAP microcarriers and MSCs was extruded as 400 um droplets into rapidly stirring chitosan. Reaction between C4S and chitosan produced a polyelectrolyte membrane, encapsulating the suspended cells and microcarriers. After buffer washes and stabilization, the resulting microcapsules were transferred to dish culture, and osteogenic induction of the encapsulated MSCs was induced with a standard cocktail. Results indicate that MSCs encapsulated in C4S-chitosan microcapsules with HAP microcarriers retain their differentiation potential towards an osteogenic lineage, and rapidly mineralize the interior of the microcapsules. Intracellular alkaline phosphatase (ALP) activity over a four week culture period, combined with increasing osteocalcin (OC) and osteopontin secretion in microcapsule cultures, confirm encapsulated MSC commitment to osteogenesis. Suprisingly, intracellular ALP activity and OC deposition in microcapsules containing HAP, but cultured without osteogenic supplements, was similar to cultures with osteogenic supplements, suggesting the occurrence of HAP-induced osteogenic differentiation. This study confirms that C4S-chitosan microcapsules containing HAP microcarriers can support MSC osteogenesis, and may be suitable as the foundation of a modular bone-regenerating therapeutic.
Presenting Author: Anil Kalra
Blast related finite element simulations are used extensively to simulate pressure waves generated by detonation of improvised explosive devices (IEDs). The physics behind the generation and propagation of blast waves are well understood, but the mechanisms of injuries caused by high pressure blast waves are not well known yet. The simulated blast pressure waves together with finite element models of animals and humans can be proved as a useful tool to understand the mechanism of injury caused by the sudden change in impedance between the fluid and solid structures. In the current research, an anatomically accurate finite element model of a pig head was constructed to calculate the pressure gradient change inside the different regions of the brain. The blast related high pressure waves were generated using the Arbitrary Lagrangian-Eulerian (ALE) formulation and fluid structure interaction was simulated using a coupling algorithm available in an explicit code used for the simulation (LS-DYNA). A 2d to 3d mapping was performed to save the computational time and to acquire more accurate results. The simulation results show that the mesh size and density of the air domain are the important dependent variables to match the theoretically predicted pressure wave magnitude. Additionally, the simulation predicted intracranial pressure or the incident pressure is validated against theoretical results. Future studies should include a mesh sensibility study to identify the minimum size of the air domain and correlation of experimentally observed injuries to the biomechanical parameters calculated by the finite element model.
Presenting Author: Elisabeth Steel
In order to achieve complete functional recovery of an injured nerve, neural tissue engineering and regenerative approaches seek to develop a material construct that combines several cues that promote and guide regenerating axons to reconnect with target tissue. Current scaffold design in the Sundararghavan lab combine topographical, chemical, and mechanical cues to guide and direct growth cones to increase neurite extension. To quantify neurite extension over time, chick dorsal root ganlia (DRG) are seeded on electrospun scaffolds and imaged by time lapse fluorescence microscopy in a physiologic incubation chamber. The present work has developed an experimental design that delivers electrical stimulation as an additional guidance cue to cultured cells during time lapse microscopy. Dissociated DRG were labeled in suspension prior to seeding with Vybrant DiO (Molecular Probes). Neurite outgrowth from dissociated DRG cultured on ITO glass for 24 hours was observed during live imaging while being stimulated with an alternating current of 50 mA and 7 V. Bright field and fluorescence images were acquired every 15 minutes for 24 hours at 5 different positions for each sample. The next steps are to fabricate a conductive electrospun scaffold and quantify neuronal growth during electrical stimulation using this established live cell imaging methodology.
|Location||Presenting Author||Presentation Title|
|A01||Amy Shanks||Alerting Thresholds for the Prevention of Intraoperative Awareness with Explicit Recall|
|A02||Melissa Wrobel||Aligned RGD-MeHA Nanofibers: Adhesive and Topographical Cues for Improving Nerve Regeneration|
|A03||Dalia Alzebdeh||Porous Scaffold Designs for Perfusion Culture and Liver Tissue Engineering: Evaluation of Cell-Loading Efficiency and Seeding Time|
|A04||Ingrid Ganda||PAMAM Dendrimer Nanocarriers: a New Platform for Peptide Vaccine Delivery and its Application to a Chlamydia trachomatis infection model|
|A05||Lin Yang||PEGylated PAMAM Dendrimer: A Microscopic View from Atomistic Computer Simulations|
|A06||Elizabeth Bielski||Synthesis, Characterization, Cellular Internalization and Mitochondrial Targeting of Triphenylphosphonium-conjugated PAMAM Dendrimer Nanocarriers|
|A07||Qian Zhong||Poly(amidoamine) Dendrimer Nanocarriers for the Delivery of Therapeutics to and through the Lungs: Effect of PEGylation on the Pharmacokinetics, Biodistribution and Lung Tissue Distribution|
|A08||Qian Zhong||Uptake, Co-localization and Cytotoxicity of Acid-labile PEGylated Poly(amidoamine)-Doxorubicin Conjugates in an in vitro Model of the Lung Adenocarcinoma|
|A09||Ramkumar Tiruvannamalai-Annamalai||Rapid Assembly of Perfusable and Vascularizable Modular Constructs for Hepatic Tissue Engineering|
|A10||Divya Subramonian||SUMO-2/3 Modification of Kinetochore Proteins including Nuf2 Is Required for CENP-E Localization to Kinetochores and Cell Cycle Progression during Mitosis|
|A11||Alison Jacob||Effect of Glycidyl Methacrylate Conjugation and Crosslinking on Chitosan Material Properties|
|A12||Tonya Whitehead||Extended Protein Release from Microspheres Incorporated in Electrospun HA to Support Nerve Repair|
|Location||Presenting Author||Presentation Title|
|B01||David Letteer||Microencapsulated Mesenchymal Stem Cells As a Platform for Engineering an Injectable Cartilage Repair/Regeneration Strategy|
|B02||Alexander Gagliardi||Modular Tissue Engineering: Chitosan-GAG Fibers Formed From an Ionic Complex|
|B03||Hamzeh Omar||Directing Neuron Growth Using Mechanical Tension|
|B04||Anant Patel||Gene Silencing with Multivalent siRNA-Poly(amidoamine) Dendrimer Conjugates|
|B05||Vishal Gupta||Effect of Vehicle Front End Profiles Leading to Pedestrian Secondary Head Impact to Ground|
|B06||Zhengguang Wang||Development of Human Neck FE Model to Predict Cervical Soft Tissue Injury|
|B07||Ming Shen||Development and parametric analysis of a finite element femur model of a 10 years old child|
|B08||Rouhollah Hamtaei||Accelerated MR T2 mapping via random view sharing of higher order k-space|
|B09||Rouhollah Hamtaei||3D Model of the Optic Radiation using Susceptibility Weighted Imaging|
|B10||Brijesh Yadav||Evaluating placental growth in normal murine pregnancy using Tissue Similarity Mapping and DCE-MRI|
|B11||Uday Krishnamurthy||Phase contrast MRI of the human umbilical cord|