Chip-based liver equivalents for toxicity testing - organotypicalness versus cost-efficient high throughput

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Drug-induced liver toxicity dominates the reasons for pharmaceutical product ban, withdrawal or non-approval since the thalidomide disaster in the late-1950s. Hopes to finally solve the liver toxicity test dilemma have recently risen to a historic level based on the latest progress in human microfluidic tissue culture devices. Chip-based human liver equivalents are envisaged to identify liver toxic agents regularly undiscovered by current test procedures at industrial throughput. In this review, we focus on advanced microfluidic microscale liver equivalents, appraising them against the level of architectural and, consequently, functional identity with their human counterpart in vivo. We emphasise the inherent relationship between human liver architecture and its drug-induced injury. Furthermore, we plot the current socio-economic drug development environment against the possible value such systems may add. Finally, we try to sketch a forecast for translational innovations in the field

Measurement and Simulation of Permeation and Diffusion in Native and Cultivated Tissue Constructs

Characterization of native skin or cultured 3D skin models with respect to permeability plays an important role for the development and testing of pharmaceuticals and cosmetics. Extensive efforts have been dedicated to determining the key parameters describing permeability and diffusion. Whereas respective methods are well established for native skin biopsies, only few are available for 3D skin models, as these have usually much lower dimensions. In this chapter, some fundamentals about permeation and diffusion as well as state of the art of measurement methods used for skin biopsies are summarized. An alternative method for the determination of the permeation in a membrane insert system and the use of a modular simulation to support permeability studies is presented and discussed

Fluorescent optical fiber sensors for cell viability monitoring

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.A new simple method for non-invasive cell culture viability monitoring based on vital fluorescent stains is introduced, and its efficiency for long-term experiments on cells is demonstrated. In contrast to common methods for cell viability control, which are usually either destructive (like flow-type counters or dead cells coloring and counting), or hardly quantitative like fluorescent microscopy, the method described is automated, does not require the removal of cells from their growth area and is sensitive enough to deal with as low as tens of cells

Hollow fibres integrated in a microfluidic cell culture system

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.For in vitro drug screening a modified perfusion micro-bioreactor system with integrated hollow fibres will be demonstrated. This biocompatible system consists of an integrated closed flow circuit that includes reservoirs and pneumatic micro pumps. Additional optical online-monitoring devices allow the observation during the cell cultivation. The embedded hollow fibre system which acts as cell carrier consists of a biodegradable biopolymer. One option to fabricate such 3D structures is the technology of Organ Printing which is realised by an adapted rapid prototyping system entitled 3D Scaffold Printer. With this device specimens consisting of tubes with a diameter smaller than 2 mm can be prepared. It should be possible to cultivate the hollow fibres inside and outside with different kinds of cells and therefore generate models of complex tissues

Automated Micro-PIV measurement in Lab-on-a-Chip systems

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Flow rate and wall shear stress are important parameters for perfused cell culture systems and should be monitored. An easy and non-invasive method is the particle image velocimetry (PIV). In this work PIV was used to characterize a cell culture system with included peristaltic pump. The time-dependent flow profile was measured on several points of the chip for different pumping speeds to figure out which forces are applied to dissolved and adherent cells. The results can be used to improve the developed pump in respect to its layout, the excitation and the position within the chip

Solid-Phase Extraction of Aquatic Organic Matter: Loading-Dependent Chemical Fractionation and Self-Assembly

Dissolved organic matter (DOM) is an important component in marine and freshwater environments and plays a fundamental role in global biogeochemical cycles. In the past, optical and molecular-level analytical techniques evolved and improved our mechanistic understanding about DOM fluxes. For most molecular chemical techniques, sample desalting and enrichment is a prerequisite. Solid-phase extraction has been widely applied for concentrating and desalting DOM. The major aim of this study was to constrain the influence of sorbent loading on the composition of DOM extracts. Here, we show that increased loading resulted in reduced extraction efficiencies of dissolved organic carbon (DOC), fluorescence and absorbance, and polar organic substances. Loading-dependent optical and chemical fractionation induced by the altered adsorption characteristics of the sorbent surface (styrene divinylbenzene polymer) and increased multilayer adsorption (DOM self-assembly) can fundamentally affect biogeochemical interpretations, such as the source of organic matter. Online fluorescence monitoring of the permeate flow allowed to empirically model the extraction process and to assess the degree of variability introduced by changing the sorbent loading in the extraction procedure. Our study emphasizes that it is crucial for sample comparison to keep the relative DOC loading (DOCload [wt %]) on the sorbent always similar to avoid chemical fractionation

Automated universal chip platform for fluorescence based cellular assays

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.The advantage of cell based assays used as biosensors is the direct access to hardly obtainable parameters like toxicity, mutagenicity and pharmacological effectiveness. Within the last few years we established a micro fluidic platform including a peristaltic micro pump as well as several valves, manifolds and micro channels [1]. For optical online monitoring the micro fluidic system is bonded to a glass slide. Furthermore the biochip is fixed on an electrically heated support. The pneumatically actuated peristaltic pump as well as the temperature control is performed by a control device. For the fluorescence based online monitoring a robotic guided fluorescence measurement module was developed, which supports the detection of fluorescence in microtiter plates and microfluidic systems. This measurement module allows the fluorescence detection of two different excitation / detection wavelengths (480 / 530 nm and 570 / 620 nm) and was successfully characterised using EGFP and Rhodamine 6G. Additionally three cell based assays with bacterial, yeast and human cells were characterized

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Development of 3D human intestinal equivalents for substance testing in microliter-scale on a multi-organ-chip : From 23rd European Society for Animal Cell Technology (ESACT) Meeting: Better Cells for Better Health Lille, France. 23-26 June 2013

First published by BioMed Central: Jaenicke, Annika; Tordy, Dominique; Groeber, Florian; Hansmann, Jan; Nietzer, Sarah; Tripp, Carolin; Walles, Heike; Lauster, Roland; Marx, Uwe: Development of 3D human intestinal equivalents for substance testing in microliter-scale on a multi-organ-chip. - In: BMC Proceedings. - ISSN 1753-6561 (online). - 7 (2013), suppl. 6, P65. - doi:10.1186/1753-6561-7-S6-P65