Debra T. Auguste

Nanoengineering the heart: conductive scaffolds enhance connexin 43 expression.

Scaffolds that couple electrical and elastic properties may be valuable for cardiac cell function. However, existing conductive materials do not mimic physiological properties. We prepared and characterized a tunable, hybrid hydrogel scaffold based on Au nanoparticles homogeneously synthesized throughout a polymer templated gel. Conductive gels had Youngs moduli more similar to myocardium relative to polyaniline and polypyrrole, by 1-4 orders of magnitude. Neonatal rat cardiomyocytes exhibited increased expression of connexin 43 on hybrid scaffolds relative to HEMA with or without electrical stimulation.

Embryoid body morphology influences diffusive transport of inductive biochemicals: A strategy for stem cell differentiation☆

Differentiation of human embryonic stem (hES) cells into cells for regenerative medicine is often initiated by embryoid body (EB) formation. EBs may be treated with soluble biochemicals such as cytokines, growth factors and vitamins to induce differentiation. A scanning electron microscopy analysis, conducted over 14 days, revealed time-dependent changes in EB structure which led to the formation of a shell that significantly reduced the diffusive transport of a model molecule (374 Da) by >80%. We found that the shell consists of 1) an extracellular matrix (ECM) comprised of collagen type I; 2) a squamous cellular layer with tight cell-cell adhesions associated with E-cadherin; and 3) a collagen type IV lining indicative of a basement membrane. Disruption of the basement membrane, by either inhibiting its formation with noggin or permeabilizing it with collagenase, resulted in recovery of diffusive transport. Increasing the diffusive transport of retinoic acid (RA) and serum in EBs by a 15-min collagenase digestion on days 4, 5, 6 and 7 promoted neuronal differentiation. Flow cytometry and quantitative RT-PCR analysis of collagenase-treated EBs revealed 68% of cells expressing neural cell adhesion molecule (NCAM) relative to 28% for untreated EBs. Our results suggest that limitations in diffusive transport of biochemicals need to be considered when formulating EB differentiation strategies.

A Drug‐Delivery Vehicle Combining the Targeting and Thermal Ablation of HER2+ Breast‐Cancer Cells with Triggered Drug Release

Breast cancer is the second leading cause of cancer-related deaths in women, surpassed only by lung cancer. [1] Current clinical therapies target the estrogen receptor (ER) and human epidermal growth factor receptor-2 (HER2) to reduce cancer-cell proliferation. These methods are often used in conjunction with surgery, chemotherapy, and/or radiation in efforts to eradicate the disease. However, 25 % of patients face tumor recurrence and resistance within 5 years after treatment. [2] Ideally, the initial treatment would supply a robust, broad-spectrum therapy to eliminate all cancer

Nanocarrier cross-linking density and pH sensitivity regulate intracellular gene transfer.

Treatment of diseases on the molecular level by genetic material is limited by effective delivery mechanisms. We focused on the synthesis of a pH-sensitive gene delivery vehicle based on dimethylaminoethyl methacrylate (DMAEMA) with tunable swelling, cross-linking density, and DNA release kinetics within the endosomal pH range. Our strategy, which utilized a single step for DNA encapsulation, enhanced gene transfection efficiency and reduced cytotoxicity relative to polyethyleneimine (PEI) and poly-L-lysine (PLL).

Feedback-regulated paclitaxel delivery based on poly(N,N-dimethylaminoethyl methacrylate-co-2-hydroxyethyl methacrylate) nanoparticles.

pH-Sensitive poly(N,N-dimethylaminoethyl methacrylate (DMAEMA)/2-hydroxyethyl methacrylate (HEMA)) nanoparticles were prepared for the triggered release of paclitaxel within a tumor microenvironment. Tumors exhibit a lower extracellular pH than normal tissues. We show that paclitaxel release from DMAEMA/HEMA particles can be actively triggered by small, physiological changes in pH (within 0.2-0.6 pH units). Monodispersed nanoparticles were synthesized by forming an O/W emulsion followed by photopolymerization. Particles were characterized by transmission electron microscopy, dynamic light scattering, electrophoresis, and cytotoxicity. High release rates and swelling ratios are achieved at low pH, low crosslinking density, and high content of DMAEMA. Paclitaxel release is limited to 9% of the payload at pH 7.4 after a 2-h incubation at 37 degrees C. After adjusting to pH 6.8, 25% of the payload is released within 2h. Cell viability studies indicate that pH-sensitive DMAEMA/HEMA nanoparticles are not cytotoxic and may be used as an efficient, feedback-regulated drug delivery carrier.

ICAM-1 as a molecular target for triple negative breast cancer

Significance Triple negative breast cancers (TNBCs) have a poor prognosis (5-y survival of 74.5%) among all breast cancer patients (5-y survival of greater than 95%) because of the aggressiveness of the disease and the lack of targeted therapeutics. We show that intercellular adhesion molecule-1 (ICAM-1) is differentially expressed in human TNBC tumor tissues by immunohistochemistry and in human TNBC cell lines via quantification of gene and protein expression. Iron oxide nanoparticles functionalized with ICAM-1 antibody (ICAM-IONP) were synthesized as MRI probes. An in vivo signal enhancement of 2.6-fold for ICAM-IONPs was measured relative to controls, demonstrating that ICAM-1 is a potential diagnostic and therapeutic target for TNBC treatment. Triple negative breast cancers (TNBCs) have a high mortality rate owing to aggressive proliferation and metastasis and a lack of effective therapeutic options. Herein, we describe the overexpression of intercellular adhesion molecule-1 (ICAM-1) in human TNBC cell lines and tissues, and demonstrate that ICAM-1 is a potential molecular target and biomarker for TNBC therapy and diagnosis. We synthesized ICAM-1 antibody-conjugated iron oxide nanoparticles (ICAM-IONPs) as a magnetic resonance imaging (MRI) probe to evaluate tumor targeting. Quantitative analysis of ICAM-1 surface expression predicted the targeting capability of ICAM-IONPs to TNBC cells. MRI of the TNBC xenograft tumor after systemic administration of ICAM-IONPs, coupled with iron quantification and histology, demonstrated a significant and sustained MRI contrast enhancement and probe accumulation in tumors with ICAM-1 overexpression relative to control. Identification of ICAM-1 as a TNBC target and biomarker may lead to the development of a new strategy and platform for addressing a critical gap in TNBC patient care.

The role of antibody synergy and membrane fluidity in the vascular targeting of immunoliposomes.

Targeted drug delivery to inflamed or injured vascular endothelial cells (ECs) and smooth muscle cells (SMCs) may provide a precise and effective therapeutic treatment for cardiovascular diseases. Upregulation of cytokine-regulated cell surface receptors, intercellular cell adhesion molecule-1 (ICAM) and endothelial-leukocyte adhesion molecule-1 (ELAM), on ECs and SMCs are used to target drug delivery vehicles. Recent studies demonstrate clustering of these molecules in lipid rafts may affect binding due to a nonhomogenous presentation of antibodies. We hypothesized that altering the antibody ratio for ICAM and ELAM (aICAM:aELAM) and mobility would influence cellular targeting. To alter antibody mobility, liposomes were prepared from either 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC, C(18:1), T(m)=-20 degrees C) or 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC, C(16:0), T(m)=42 degrees C) which are in the liquid crystalline (L(alpha)) and gel phase (L(beta)) at 37 degrees C, respectively. We report that cellular binding of DOPC immunoliposomes by ECs is maximal at an equimolar ratio of aICAM:aELAM whereas DPPC immunoliposomes showed no ratio dependence and binding was reduced by more than 2-fold. SMCs, which do not express ELAM, show a dependence on aICAM surface density. These results suggest that antibody mobility and molar ratio play a key role in increasing receptor-mediated cell targeting.

Conductive, physiologically responsive hydrogels.

Coupling molecular sensing with electrical conductivity may provide an important and valuable resource in assessing disease pathology. Here, we introduce pH-responsive hydrogels with homogeneously synthesized gold (Au) nanoparticles that reversibly alter conductivity through pH-induced volumetric swelling. These intelligent hybrid materials respond to physiological pH shifts (pH 7.4 to 5.5) that can (1) alter the conductivity of the gel or (2) create conductive conduits via micropatterned arrays.

Cancer targeted therapeutics: From molecules to drug delivery vehicles

The pitfall of all chemotherapeutics lies in drug resistance and the severe side effects experienced by patients. One way to reduce the off-target effects of chemotherapy on healthy tissues is to alter the biodistribution of drug. This can be achieved in two ways: Passive targeting utilizes shape, size, and surface chemistry to increase particle circulation and tumor accumulation. Active targeting employs either chemical moieties (e.g. peptides, sugars, aptamers, antibodies) to selectively bind to cell membranes or responsive elements (e.g. ultrasound, magnetism, light) to deliver its cargo within a local region. This article will focus on the systemic administration of anti-cancer agents and their ability to home to tumors and, if relevant, distant metastatic sites.

The effect of swelling and cationic character on gene transfection by pH-sensitive nanocarriers

We synthesized a series of pH-sensitive vehicles, composed of dimethylaminoethyl methacrylate (DMAEMA) and 2-hydroxyethyl methacrylate (HEMA), to optimize the triggered release of DNA for gene transfection. The purpose of this study was to assess the role of swelling and cationic character independently on transfection; both of which may affect DNA release. Gene transfection was performed by delivering plasmid DNA (pDNA) encoding for luciferase. DNA release was controlled via volumetric swelling by regulating the endosomal pH as a result of inhibiting V ATPases using bafilomycin A1. Increasing the cationic character from 10 to 30 mol% DMAEMA did not increase transfection when swelling was inhibited. Transfection was significantly affected by the rate of pDNA release. pH-sensitive nanocarriers were also compared to vehicles comprised of polyethyleneimine (PEI), dioleoyl triammonium propane (DOTAP), and poly(lactic-co-glycolic acid) (PLGA, 50:50). pDNA encapsulating DMAEMA/HEMA nanoparticles and PEI/pDNA complexes had reduced transfection when V ATPases were inhibited, whereas pDNA encapsulating PLGA nanoparticles showed no endosomal pH dependence. DMAEMA/HEMA nanoparticles cross-linked with 3 mol% tetraethylene glycol dimethacrylate (TEGDMA) reported equivalent or greater gene transfection relative to the nanocarriers tested at 24 and 48 h.