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ABSTRACT: Medium to high throughput screening for toxicity testing can provide a wealth of information with significant time and cost savings. New technologies, such as microfabrication, microfluidics and chip-based technology, combined with advanced cell culture and detection techniques, open up new opportunities in toxicity testing. In this chapter, fundamentals of microfabrication and microfluidics are discussed with a focus on the broad and novel applications on toxicity studies enabled by these technologies. Emphasis is placed on microscale cell and tissue culture models for medium and high throughput systemic toxicity studies in vitro.
Advances in experimental medicine and biology 01/2012; 745:181-209. · 1.09 Impact Factor
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ABSTRACT: We have designed, built and tested a three-dimensional (3-D) cell culture system on modified microplates for high-throughput, real-time, proliferation and cytotoxicity assays. In this 3-D culture system, cells expressing the enhanced green fluorescent protein (EGFP) were cultured in nonwoven polyethylene terephthalate (PET) fibrous scaffolds. Compared to 2-D cultures in conventional microplates, 3-D cultures gave more than 10-fold higher fluorescence signals with significantly increased signal-to-noise ratio (SNR), thus extending the application of conventional fluorescence microplate readers for online monitoring of culture fluorescence. The 3-D system was successfully used to demonstrate the effects of fetal bovine serum, fibronectin coating of PET fibers, and cytotoxicity of dexamethasone on recombinant murine embryonic stem D3 cells. The dosage effects of 5-fluorouracil and gemcitabine on high-density colon cancer HT-29 cells were also tested. These studies demonstrated that the 3-D culture microplate system with EGFP expressing cells can be used as a high-throughput system in drug discovery and bioprocess development.
Journal of biotechnology 01/2011; 151(2):186-93. · 2.88 Impact Factor
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ABSTRACT: Cell culture plays a fundamental role in the biotechnology and pharmaceutical industries, impacting both drug discovery and manufacturing as well as regenerative medicine. In drug discovery, cell-based assays are increasingly being used for drug target validation and drug ADMET (absorption, distribution, metabolism, elimination and toxicity) studies because cells can provide more representative responses to drugs than simple molecular assays and are easier to use in a high-throughput format than animals. There are, however, intrinsic drawbacks associated with conventional in vitro cellular tests using two-dimensional cultures, in that they lack a three-dimensional (3D) scaffold to support cell growth and proper tissue function, and cannot mimic in vivo cellular conditions. Tailoring scaffold properties for 3D cell cultures is therefore essential in developing a representative in vitro tissue model for cytotoxicity assays. Recently, microfluidic bioreactors with miniaturized culturing vessels and high controllability for operation and on-line monitoring/sensing have gained popularity in bioprocess development and cell-based assays. The advancement in this field has been enabled by the development of novel cell lines and reporter gene techniques, as well as new microfabrication, microfluidics and optical and electrochemical sensor technologies. Non-invasive detection methods using reporter genes and label-free techniques allow for real-time dynamic monitoring of viable cell number and cellular activities. Microbioreactors with continuous perfusion allow for long-term culturing to study chronic toxicity effects. Systemic toxicity and interactions between different cell types can also be studied on a biochip. High-density microfluidic arrays provide a platform for future high-throughput and high-content screening that will contribute to drug discovery and bioprocess development.
Current opinion in drug discovery & development 02/2008; 11(1):111-27. · 4.20 Impact Factor
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ABSTRACT: One important application of tissue engineering is to provide novel in vitro models for cell-based assays. Perfusion microbioreactor array provides a useful tool for microscale tissue culture in parallel. However, high-throughput data generation has been a challenge. In this study, a 4 x 4 array of perfusion microbioreactors was developed for plate-reader compatible, time-series quantification of cell proliferation, and cytotoxicity assays. The device was built through multilayer soft lithography. Low-cost nonwoven polyethylene terephthalate fibrous matrices were integrated as modular tissue culture scaffolds. Human colon cancer HT-29 cells with stable expression of enhanced green fluorescent protein were cultured in the device with continuous perfusion and reached a cell density over 5 x 10(7) cells/mL. The microbioreactor array was used to test a chemotherapeutic drug 5-FU for its effect on HT-29 cells in continuous perfusion 3D culture. Compared with conventional 2D cytotoxicity assay, significant drug resistance was observed in the 3D perfusion culture.
Biotechnology Progress 26(4):1135-44. · 2.34 Impact Factor
