Lung Tissue Engineering The Current State of Play

The biological function of the lung is to facilitate exchange of oxygen and carbon dioxide between the cardiovascular circulation and the environment. The lung is a physiologically and anatomically complex vital organ that is hallmarked by a compartmentalized tissue architecture. It is convenient to divide the lung into two anatomically and functionally distinct units, namely the proximal and distal airways. The proximal airways (and proximal pulmonary arteries) are smooth muscle-lined conduits...

Defined Viral and Cellular Pathways and Designed Host Cells

In a related system with the stably integrated Tat-responsive reporter cassette, the activity ofAZT was further characterized by transfection of an expression plasmid for Tat in the presence or absence of AZT 65 . Such a system where isolated viral events are probed in cells allows drug screens without the hazards ofviable virus, and this may be advantageous for more dangerous pathogens than HIV. However, as AZT interferes with reverse transcription the reporter signal strength was not...

Tumor Cell Lines Sometimes an Alternative

Compared to primary cells, permanent cell lines would represent continuous, stable and rather homogeneous test systems. Nevertheless, cell lines are - with few exceptions - less popular metabolic models. Of the available liver cell lines, only in HepG2 (the dominant cell line in drug metabolism) and in the more recently identified hepatoma BC2, can phase I and II enzymes be induced, while basal activity remains very low (reviewed in 8 ). The human Caco-2 cell line, developed from an intestinal...

Cell Lines and Primary Tissues for InVitro Evaluation ofVaccine Efficacy 153

6.2 Measurement of Antigen Expression 155 6.3 Post-Vaccination Testing 158 6.3.1 Ex-Vivo Detection of Antigen-Specific T Cells 160 6.3.1.2 Cytokine Capture Assay and Intracellular Cytokine Staining 162 6.3.1.3 Measurement of T-Cell Cytotoxicity 163 6.3.2 Current Knowledge on T-Cell Responses in Vaccine Trials 165 6.4 Future Directions 167 References 168

The Operation of Bioreactors

Bioreactors allow for different process strategies including batch, fed-batch, or continuous cultivation (Figs. 2.2 and 2.3). Continuous perfusion, in particular, enables cultivation to be carried out under constant and controlled environmental conditions 44, 51, 68, 69, 73, 74 . Martin et al. 7 summarized some of the effects of direct perfusion on tissue-specific properties such as growth, differentiation and mineralized matrix deposition by bone cells, the proliferation of human oral...

Suitability and Limitations of Primary Cells as Physiologic Models

Growing numbers of hits from primary high-throughput discovery programs generate the need for early, fast and robust lead candidate identification. In order to avoid creating a bottleneck at this stage, decisions on compound selection rejection must be made before animal testing, with the required throughput and minimal substance use. For the accurate prediction of compound specificity and related toxicity, these assays must rely on physiological models that clearly reflect the situation in the...

Intracellular Recording of Electroactive Cells Chip Based Automated Patch Clamp Recording

Fundamental cellular processes, such as neuronal signaling and the contraction of heart and skeletal muscle cells, are regulated by ion channels. A number of diseases which are caused by pathology of ion channels - so-called channelopathies 35 - originate from the loss or dysfunction of ion channels. Some well-known channelopathies affect the central nervous system (episodic ataxias, familial hemiplegic migraine and inherited epilepsies), skeletal muscles (myotonias, periodic paralyses,...

Measurement of TCell Cytotoxicity

Cytotoxicity, which has been shown to be important in clearing many viral infections 70-72 , may be a more reliable indicator of the effector function of antigen-specific CD8+ T cells than cytokine synthesis. It could be important, for example, in controlling HIV-1 pathogenesis, though this has recently been questioned as HIV-1 antigen-specific CD8+ T cells appear to kill infected cells at a slow rate in vivo 43 . As previously alluded to, measuring IFN-y-secreting CD8+ T cells does not provide...

Alternative Methods Used in the Development and Safety Testing of Drugs Biologicals and Medical Devices Table 101

As outlined above, the number of experimental animals used by the drug industry in Germany has decreased during the past 25 years by more than 90 (see Fig. 10.2). This development is typical for the international drug industry, and is due to a general change of models that are used in the life sciences. Research in pharmacology is no longer centered around animal models of disease but rather is focused on molecular models. Biochemical pharmacology has been replaced by molecular pharmacology,...

The Inhalation of Air Contaminants

Air contaminants are exogenous substances in indoor or outdoor air, and include both particulates and gaseous contaminants that may cause adverse health effects in humans or animals. In addition, they may affect plant life and impact on the global environment by changing the atmosphere of the Earth 5 . Various physical, chemical and dynamic processes may generate air pollution leading to the emission of gases, particulates, or mixtures of these, into the atmosphere 6 . Whilst major attempts...

Scaffolds for Liver Tissue Engineering

In general, either mixed cultures of primary isolated cells 68 or freshly isolated purified primary hepatocytes are applied to the scaffold 69 . In order to generate a functional liver construct, the liver cells, once seeded onto the scaffolds, must migrate into the scaffold interior, expand, and populate the new tissue constructs. To facilitate these processes the scaffolds must provide a biocompatible surface suitable for cell recognition and adherence. Following attachment, the cells must...

InVitro BBB Models Cells and Devices

A minimal approach to an in-vitro BBB model focuses mainly on brain microvascular ECs (see Table 1.3). For the past three decades, capillaries have been prepared from the brains of various species of embryonic or adult animals. Brain ECs have been isolated and primary ECs were cultured in vitro. The disadvantages of using primary cultures include the extensive use of animals, tedious, complicated protocols for cell isolation, slow cell proliferation rates, the limitation in passaging these...

References

Casarett and Doull's Toxicology the Basic Science of Poisons, 6th edition. McGraw-Hill, New York. 2 Greenberg, M. I., Hamilton, R. J., Phillips, S. D., McCluskey, G. J. (Eds.) (2003). Occupational, Industrial, and Environmental Toxicology, 2nd edition. Mosby, Inc., Philadelphia, Pennsylvania. 3 Johnson, D. L., Swift, D. L. (1997). Sampling and sizing particles. In Dinardi, S. R. (Ed.), The Occupational Environment - Its evaluation and Control. American Industrial...

Selection of the Most Suitable Cell Line

A selected cell line for HTS (Fig. 5.1) must express the desired function in the correct signal context with a stable and reproducible signal window. The different cell types from which to choose have different advantages primary cells best resemble the physiological situation 3 , but cultivation and available cell numbers are critical issues, even when using techniques such as conditional immortalization 4 or stem cell differentiation. A large panel of easy-to-cultivate immortalized cell lines...

Current Knowledge on TCell Responses in Vaccine Trials

Knowledge gained from analyzing T-cell responses in natural infections, as in HIV-1 infection previously described (above), has provided valuable insights into what is needed for vaccine design and vaccination schedules. Today, novel technological advances are being made, leading in turn to improved ways of measuring CD8+ T-cell responses. Increasingly, these responses are being tested for in animal models and clinical trials of new vaccines. Against HIV infection, much of the recent effort to...

The BBB a Neurovascular Physiological Unit The Concept

The BBB, which separates the blood from the brain, and vice versa, was first described in 1885 by Paul Ehrlich and confirmed later in 1909 by Edwin Goldman. Both investigators showed that, following intravenous injection, trypan blue (an albumin-binding dye) was dispersed throughout the whole body, except for the brain. Conversely, injection of this dye into the brain subarachnoidal space selectively stained only the brain. Reese and Karnovsky 161 , Brightman and Reese 162 and others,...

Assays and Target Based Applications of HCS

These assays applications can be grouped into two classes, namely target-orientated or mechanism-orientated. Target-based approaches seek the activity or localization of a defined protein within the cells, whereas mechanism-based approaches measure general cellular parameters such as intercellular communication or multi-faceted phenomena, such as apoptosis. Today, GPCRs are becoming increasingly accepted as excellent targets in HCS because of the availability of appropriate assay techniques for...

Elispot Assay

This assay depends on T cells responding specifically to antigen by the synthesis and secretion of cytokines, particularly IFN-y. The principle of the ELISPOT assay is that secreted IFN-y from stimulated antigen-specific T cells is captured by an anti-IFN-y monoclonal antibody immobilized on a nitrocellulose membrane. The captured IFN-y is then detected by a second anti-IFN-y antibody conjugated to an enzyme cytokine spots on the membrane which represent individual IFN-y-secreting T cells are...

Trends in Tissue Engineering Realistic InVitro BBB Pharmacological Models

The ECM is crucial for the culture of brain microcapillary ECs and the establishment of tight junctions 204 . In most in-vitro BBB models the surface of the transwell inserts is coated with rat tail type I collagen, to support and promote EC monolayer formation 205-207 . However, other ECM molecules, such as type IV collagen, fibronectin and laminin, either alone or in combination, were also shown significantly to elevate the TEER of low-resistance porcine brain endothelial monolayers 171 ....

Potential of Alveolar Tissue Models as Disease Models in Pharmaceutical Sciences

Engineered alveolar tissue models that recapitulate physiological and pharmacological characteristics of native distal lung tissue would be invaluable research tools, with broad applications as pharmacological models of normal and pathological tissues, and novel venues for investigation of pulmonary toxicology and infectivity. The refinement of traditional 2D models used to investigate drug permeability in lung tissue 142, 154 will result in a more physiologically relevant model to study drug...

Cytokine Capture Assay and Intracellular Cytokine Staining

Brefeldin Ics

In addition to the measurement of secreted cytokines, other methods aim to measure cell-associated cytokines, either in a cytokine capture assay CCA where cytokines e.g., IFN-y, IL-4 are detected on the cell surface Fig. 6.2 66 , or more commonly by intracellular cytokine staining ICS , where cytokine secretion is blocked by drugs such as brefeldin A or monensin, and cytokine accumulates in the cytoplasm Fig. 6.3 51, 67, 68 . For both methods, fluorescence-conjugated antibodies are used to bind...

Impedance Spectroscopy Screening the Cellular Parameters of Electrophysiological Inactive Cells

Measuring Extracellular Impedance

Impedance spectroscopy, which is also known as cellular dielectric spectroscopy CDS or electric impedance spectroscopy EIS , can be used to measure frequency-dependent changes in the passive electrical properties of single cells or complex tissues by applying defined alternate currents. The bioimpedance of single cells or complex tissues, when combined with a working and counter electrode, is determined by different cellular parameters such as the electric resistance and capacitance of the sub...

The Artificial Immune System

Artificial Lymph Nodes

In vivo, immunogenicity and effects of immunotoxicity are localized in primary immune organs such as bone marrow or thymus, or secondary immune organs such as the lymph nodes and spleen, and spread into the peripheral tissues of the body, such as the skin and gut 106 . Tissue engineering approaches can be used to remodel cascades of cellular interactions in vitro. Recently, ex-vivo-generated and cultivated lymphatic cells have been used for immune cell therapies e.g., adoptive immune responses,...

Bidez P. R. Li S. Macdiarmid A. G. Venancio E. C. Wei Y. Lelkes P. I. J. Biomater. Sci. Polym. 2006 17 199-212

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Extracellular Recording of Electrically Excitable Cells Multiple Site Recording of Field Potentials by MEAs

In general, for extracellular recording of field potentials or low-frequency potentials from electrogenic cells, glass and silicon-based MMEAs with embedded passive metal electrodes 45, 46 or integrated FETs are commonly used 7, 29, 47 . Although, in general, intracellular recording techniques are more sensitive than extracellular recordings, the latter - when carried out with MEAs - have several remarkable advantages. For example, cells cultured on substrate-integrated electrodes allow the...