3D bioprinting for reconstituting the cancer microenvironment.

The cancer microenvironment is known for its complexity, both in its content as well as its dynamic nature, which is difficult to study using two-dimensional (2D) cell culture models. Several advances in tissue engineering have allowed more physiologically relevant three-dimensional (3D) in vitro cancer models, such as spheroid cultures, biopolymer scaffolds, and cancer-on-a-chip devices. Although these models serve as powerful tools for dissecting the roles of various biochemical and biophysical cues in carcinoma initiation and progression, they lack the ability to control the organization of multiple cell types in a complex dynamic 3D architecture. By virtue of its ability to precisely define perfusable networks and position of various cell types in a high-throughput manner, 3D bioprinting has the potential to more closely recapitulate the cancer microenvironment, relative to current methods. In this review, we discuss the applications of 3D bioprinting in mimicking cancer microenvironment, their use in immunotherapy as prescreening tools, and overview of current bioprinted cancer models

MAR(S)2: Methodology to articulate the requirements for security In SCADA

Security requirement is an important aspect of system's development. There are numerous security requirements methodologies, which have been developed till date. Research is still going on to improve or create new methodologies that will make a system as secure as possible. Asset management, risk assessment, validation of functional and non-functional security requirements and security requirements elicitation are some of the important part of a security requirements methodology. However most of the security requirements methodologies in use today such as SQUARE, UMLSec, Secure Tropos and CORAS fail to perform one or more of these functions. Additionally, very few methodologies focus on critical infrastructure industrial systems like SCADA. This paper introduces a methodology (MAR(S)2) that incorporates all the important functions, which will produce a strong methodology that produces a profound and well-defined security requirements for SCADA systems

Effect of Annealing Time and Heat Flux on Solvothermal Synthesis of CIGS Nanoparticles

CuInxGa(1-x)Se2 (CIGS) is a renowned absorbing material in solar cell application due to its wide and tunable direct bandgap with high absorption coefficient. The highest efficiency achieved on lab scale device is 22.6% which is competitive to Si based solar cells. CIGS nanoparticles are prominent materials for solar photovoltaic applications due to its high surface to volume ratio and for its use in relatively low processing temperature. In the study, CIGS nanoparticles are synthesized using modified solvothermal method in which the size and agglomeration of CIGS nanoparticles are controlled by introducing ammonium halides. The formation mechanism of CIGS nanoparticles while heating at 230 °C in hot air oven and in muffle furnace for various time durations are studied and analysed in detailed. The crystal phase and crystallite size are evaluated using X-ray diffraction and the phase is confirmed by Raman spectroscopy. The synthesized CIGS nanoparticles from 5 hours and 7 hours of reaction time exhibited tetragonal chalcopyrite crystal structure with an average crystallite size of 41 nm in hot air oven and 125 nm in furnace. The optical band gap of the CIGS nanoparticles measured by UV-Vis-NIR spectroscopy is found to be 1.52 eV for 5 hours and 1.56 eV for 7 hours of reaction time in both oven and furnace prepared samples, that indicates the quality of material is high and could be used for photovoltaic device fabrication

Studying Tumor Angiogenesis and Cancer Invasion in a Three-Dimensional Vascularized Breast Cancer Micro-Environment.

Metastatic breast cancer is one of the deadliest forms of malignancy, primarily driven by its characteristic micro-environment comprising cancer cells interacting with stromal components. These interactions induce genetic and metabolic alterations creating a conducive environment for tumor growth. In this study, a physiologically relevant 3D vascularized breast cancer micro-environment is developed comprising of metastatic MDA-MB-231 cells and human umbilical vein endothelial cells loaded in human dermal fibroblasts laden fibrin, representing the tumor stroma. The matrix, as well as stromal cell density, impacts the transcriptional profile of genes involved in tumor angiogenesis and cancer invasion, which are hallmarks of cancer. Cancer-specific canonical pathways and activated upstream regulators are also identified by the differential gene expression signatures of these composite cultures. Additionally, a tumor-associated vascular bed of capillaries is established exhibiting dilated vessel diameters, representative of in vivo tumor physiology. Further, employing aspiration-assisted bioprinting, cancer-endothelial crosstalk, in the form of collective angiogenesis of tumor spheroids bioprinted at close proximity, is identified. Overall, this bottom-up approach of tumor micro-environment fabrication provides an insight into the potential of in vitro tumor models and enables the identification of novel therapeutic targets as a preclinical drug screening platform

Tapetum-specific expression of harpin_Pss causes male sterility in transgenic tobacco

Harpin, an elicitor molecule of bacterial origin induces hypersensitive response (HR) in non-host plants. In an attempt to induce male sterility, harpin was tagged with a signal peptide and expressed downstream to tapetum-specific TA29 promoter resulting in extracellular secretion, subsequent degeneration of tapetum and development of male sterility in tobacco. Putative transgenics were analyzed by PCR amplification of transgene, semiquantitative RT-PCR analysis from total RNA extracts from anther tissue with transgene specific probe, Western blotting using polyclonal antibody raised against harpin, by transmission and scanning electron microscopy, and by confocal microscopy of anthers and pollen at various stages of development. Varying degrees of male sterility (30–100 %) was observed with plants showing complete and partial male sterility as well as several morphological variations were seen especially in leaves and flowers. Further, some of the transgenics showed un-induced of HR-like local lesions in the vegetative tissues. HarpinPss got deposited on the pollen grains upon tapetal degeneration resulting in significant alterations in the morphology of pollen cell wall. However, megagametogenesis was not affected in complete and partial male sterile plants and female gametes were completely fertile. The complete male sterility was attributed to premature tapetal cell death due to sufficient extracellular HarpinPss accumulation whereas insufficient protein content might be the reason for partial male sterility. These findings indicate the possible use of cytotoxic HarpinPss for the development of male sterile plants

Investigation on effects of precursor pre-heat treatments on CIGS formation using spin-coated CIG precursor

A low cost, non-vacuum process involving spin coating of metallic precursors followed by selenization was substantiated for the fabrication of CIGS (CuInxGa(1−x)Se2) thin film absorber. Spin coating of CIG precursors using environmentally benign solvents and studying the effects of various heat treatments on the spin-coated CIG precursor film leads to high-quality crystalline CIGS thin films with minimum carbon impurities. In this work, effects of various heat treatments of CIG precursor (heat treatment of precursor films after each individual run of spin coating using hot plate, using air dryer, without any pre-heat treatment and heating of 30-run coated sample on hot plate for 30 mins) followed by selenization has been investigated and being reported. The as-prepared CIGS thin film samples are characterized by X-ray diffraction (XRD), Raman spectroscopy (RS), Field emission scanning electron microscopy (FESEM), UV-Vis-IR spectroscopy and X-ray photo electron spectroscopy. From XRD pattern and Raman spectra, MoSe2 phase is also observed along with tetragonal chalcopyrite CIGS phase. Through FESEM and EDS, it is observed that heating each individual run has resulted a high-quality compact dense film with minimum carbon composition. XPS also confirms the minimum carbon composition in case of preheating individual run. From UV-Vis spectra, the bandgap of the prepared CIGS material is found to be 1.5 eV, essential for the cell fabrication

Biofabrication of 3D breast cancer models for dissecting the cytotoxic response of human T cells expressing engineered MAIT cell receptors.

Immunotherapy has revolutionized cancer treatment with the advent of advanced cell engineering techniques aimed at targeted therapy with reduced systemic toxicity. However, understanding the underlying immune-cancer interactions require development of advanced three-dimensional (3D) models of human tissues. In this study, we fabricated 3D tumor models with increasing complexity to study the cytotoxic responses of CD

Chemotherapeutics and CAR-T Cell-Based Immunotherapeutics Screening on a 3D Bioprinted Vascularized Breast Tumor Model

Despite substantial advancements in development of cancer treatments, lack of standardized and physiologically-relevant in vitro testing platforms limit the early screening of anticancer agents. A major barrier is the complex interplay between the tumor microenvironment and immune response. To tackle this, a dynamic-flow based 3D bioprinted multi-scale vascularized breast tumor model, responding to chemo and immunotherapeutics is developed. Heterotypic tumors are precisely bioprinted at pre-defined distances from a perfused vasculature, exhibit tumor angiogenesis and cancer cell invasion into the perfused vasculature. Bioprinted tumors treated with varying dosages of doxorubicin for 72 h portray a dose-dependent drug response behavior. More importantly, a cell based immune therapy approach is explored by perfusing HER2-targeting chimeric antigen receptor (CAR) modified CD8+ T cells for 24 or 72 h. Extensive CAR-T cell recruitment to the endothelium, substantial T cell activation and infiltration to the tumor site, resulted in up to ≈70% reduction in tumor volumes. The presented platform paves the way for a robust, precisely fabricated, and physiologically-relevant tumor model for future translation of anti-cancer therapies to personalized medicine