Joachim Wiest

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The recent advent of microphysiological systems - microfluidic biomimetic devices that aspire to emulate the biology of human tissues, organs and circulation in vitro - is envisaged to enable a global paradigm shift in drug development. An extraordinary US governmental initiative and various dedicated research programs in Europe and Asia have led recently(More)
Cells are organic microsystems with functional compartments interconnected by complex signal chains. Intracellular signaling routes and signal reception from the extracellular environment are characterized by redundancy, i.e., parallel pathways exist. If a cell is exposed to an external "signal input", the signal processing elements within the cell provide(More)
Frequency variation in spatial frequency domain imaging is a powerful tool for adjusting the penetration depth of the imaging signal and the parameter sensitivity toward absorption and diffusive and subdiffusive scattering. Through our computational analysis, using an analytical solution of the radiative transfer equation, we add quantitation to this tool(More)
The supplementation of culture medium with fetal bovine serum (FBS, also referred to as 'fetal calf serum') is still common practice in cell culture applications. Due to a number of disadvantages in terms of quality and reproducibility of in vitro data, animal welfare concerns, and in light of recent cases of fraudulent marketing, the search for(More)
GOAL This contribution points out the need for well-defined and documented data processing protocols in microphysiometry, an evolving field of label-free cell assays. The sensitivity of the obtained cell metabolic rates toward different routines of raw data processing is evaluated. METHODS A standard microphysiometric experiment structured in discrete(More)
Screening a newly developed drug, food additive or cosmetic ingredient for toxicity is a critical preliminary step before it can move forward in the development pipeline. Due to the sometimes dire consequences when a harmful agent is overlooked, toxicologists work under strict guidelines to effectively catalogue and classify new chemical agents.(More)
Understanding the effect of exogenous substances on human skin is critical for toxicology assessment. To address this, numerous artificial models of the topmost layer of human skin, so-called reconstructed human epidermis (RhE), have been created in an attempt to produce a clear analogue for testing. Unfortunately, current testing modalities still rely on(More)
Tests for cytotoxicity–respectively biocompatibility–are performed e. g. for biological evaluation of medical devices or during the development of microphysiometric systems. Here, often cell culture methods which involve the use of fetal bovine serum (FBS) are employed. However, using FBS raises scientific and ethical concerns. In the presented work a(More)
Primarily composed of cells on a porous membrane embedded in microfluidic channels, organ-on-a-Chip (OOC) models are coming into the spotlight as an innovative, new approach to in vitro modeling. However, more work is required to understand the impact OOCs have on cellular function including basal metabolism, barrier resistance and oxygen consumption.(More)