Assessing the Permeability of Engineered Capillary Networks in a 3D Culture

Many pathologies are characterized by poor blood vessel growth and reduced nutrient delivery to the surrounding tissue, introducing a need for tissue engineered blood vessels. Our lab has developed a 3D co-culture method to grow interconnected networks of pericyte-invested capillaries, which can anastamose with host vasculature following implantation to restore blood flow to ischemic tissues. However, if the engineered vessels contain endothelial cells (ECs) that are misaligned or contain wide junctional gaps, they may function improperly and behave more like the pathologic vessels that nourish tumors. The purpose of this study was to test the resistance to permeability of these networks in vitro, grown with different stromal cell types, as a metric of vessel functionality. A fluorescent dextran tracer was used to visualize transport across the endothelium and the pixel intensity was quantified using a customized MATLAB algorithm. In fibroblast-EC co-cultures, the dextran tracer easily penetrated through the vessel wall and permeability was high through the first 5 days of culture, indicative of vessel immaturity. Beyond day 5, dextran accumulated at the periphery of the vessel, with very little transported across the endothelium. Quantitatively, permeability dropped from initial levels of 61% to 39% after 7 days, and to 7% after 2 weeks. When ECs were co-cultured with bone marrow-derived mesenchymal stem cells (MSCs) or adipose-derived stem cells (AdSCs), much tighter control of permeability was achieved. Relative to the EC-fibroblast co-cultures, permeabilities were reduced 41% for the EC-MSC co-cultures and 50% for the EC-AdSC co-cultures after 3 days of culture. By day 14, these permeabilities decreased by 68% and 77% over the EC-fibroblast cultures. Co-cultures containing stem cells exhibit elevated VE-cadherin levels and more prominent EC-EC junctional complexes when compared to cultures containing fibroblasts. These data suggest the stromal cell identity influences the functionality and physiologic relevance of engineered capillary networks

Metamaterial-inspired displacement sensor with high dynamic range

Proceedings of the 4th International Conference on Metamaterials, Photonic Crystals and Plasmonics, META 2013, United Arab Emirates, 18 Mar - 22 Mar 201: pp.274-276http://www.ieee.org/conferences_events/conferences/conferencedetails/index.html?Conf_ID=3070

Single and dual band-notched ultra-wideband antenna based on dumbbell-shaped defects and complementary split ring resonators

Printed ultra-wideband (UWB) monopole antennas are proposed with compact size and single/dual band-notched characteristics to prevent interference with nearby communication systems. It is shown that a dumbbell-shaped defect in the radiating element of a UWB monopole antenna can produce a notch band. The frequency of the notch can be easily adjusted by changing the physical dimensions of the defected structure. It is further shown that, a pair of complementary split ring resonators (CSRRs) embedded in the dumbbell-shaped defect can be used to produce a second notch. The proposed dual bandnotched antenna can be used for the rejection of interference withWorldwide Interoperability for Microwave Access (WiMAX) systems covering the 3.3-3.6 GHz band, and either lower or upper wireless local area networks (WLANs) operating in the 5.15-5.35 GHz and 5.725-5.825 GHz bands, respectively.Ali K. Horestani, Zahra Shaterian, Thomas Kaufmann, and Christophe Fumeau

Application of metamaterial-inspired resonators in compact microwave displacement sensors

There is an emerging interest in the application of metamaterial-inspired resonators for the realization of smart sensors. This paper briefly describes two main categories of metamaterial-inspired displacement sensors, namely, the displacement sensors based on shift in the resonance frequency, and sensors based on changes in the depth of resonance. The paper also highlights the advantages and disadvantages of each category in terms of dynamic range, sensitivity, compactness, and robustness to noise and changes in ambient conditions.Ali K. Horestani, Zahra Shaterian, Derek Abbott, and Christophe Fumeau