Microfluidic devices for size-dependent separation of liver cells.
ABSTRACT Liver is composed of various kinds of cells, including hepatic parenchymal cells (hepatocytes) and nonparenchymal cells, and separation of these cells is essential for cellular therapies and pharmacological and metabolic studies. Here, we present microfluidic devices for purely hydrodynamic and size-dependent separation of liver cells, which utilize hydrodynamic filtration. By continuously introducing cell suspension into a microchannel with multiple side-branch channels, cells smaller than a specific size are removed from the mainstream, while large cells are focused onto a sidewall in the microchannel and then separated into two or three groups. Two types of PDMS-glass hybrid microdevices were fabricated, and rat liver cells were successfully separated. Also, cell size, morphology, viability and several cell functions were analyzed, and the separation performances of the microfluidic devices were compared to that of a conventional centrifugal technique. The results showed that the presented microfluidic devices are low-cost and suitable for clinical use, and capable of highly functional separation with relatively high-speed processing.
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ABSTRACT: The human bone marrow-derived mesenchymal stem cells (hMSCs) consist of heterogeneous subpopulations with different multipotent properties: small and large cells with high and low multipotency, respectively. Accordingly, sorting of a target subpopulation from the others is very important to increase the effectiveness of cell-based therapy. We performed flow-based sorting of hMSCs by using optimally designed microfluidic chip based on the hydrodynamic filtration (HDF) principle. The chip was designed with the parameters rigorously determined by the complete analysis of laminar flow for flow fraction and complicate networks of main and multi-branched channels for hMSCs sorting into three subpopulations: small (< 25 μm), medium (25-40 μm), and large (> 40 μm) cells. By focusing with a proper ratio between main and side flows, cells migrate toward the sidewall due to a virtual boundary of fluid layers and would enter the branch channels. It opens the possibility of sorting stem cells rapidly without damage. The recovery was achieved over 86% for each population of cells with complete purity in small cells, but the sorting efficiency of cells is slightly lower than that of rigid model particles, due to the effect of cell deformation. Finally, we confirmed that our method could successfully fractionate three subpopulations of hMSCs by analyzing the surface marker expressions of cells from each outlet.The Analyst 12/2014; · 3.91 Impact Factor
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ABSTRACT: The liver has many complex physiological functions, including lipid, protein and carbohydrate metabolism, as well as bile and urea production. It detoxifies toxic substances and medicinal products. It also plays a key role in the onset and maintenance of abnormal metabolic patterns associated with various disease states, such as burns, infections and major traumas. Liver cells have been commonly used in in vitro experiments to elucidate the toxic effects of drugs and metabolic changes caused by aberrant metabolic conditions, and to improve the functions of existing systems, such as bioartificial liver. More recently, isolated liver perfusion systems have been increasingly used to characterize intrinsic metabolic changes in the liver caused by various perturbations, including systemic injury, hepatotoxin exposure and warm ischemia. Metabolic engineering tools have been widely applied to these systems to identify metabolic flux distributions using metabolic flux analysis or flux balance analysis and to characterize the topology of the networks using metabolic pathway analysis. In this context, hepatic metabolic models, together with experimental methodologies where hepatocytes or perfused livers are mainly investigated, are described in detail in this review. The challenges and opportunities are also discussed extensively.Metabolites. 12/2012; 2(1):268-91.
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ABSTRACT: A new microchannel with a series of symmetric sharp corner structures is reported for passive size-dependent particle separation. Micro particles of different sizes can be completely separated based on the combination of the inertial lift force and the centrifugal force induced by the sharp corner structures in the microchannel. At appropriate flow rate and Reynolds number, the centrifugal force effect on large particles, induced by the sharp corner structures, is stronger than that on small particles; hence after passing a series of symmetric sharp corner structures, large particles are focused to the center of the microchannel, while small particles are focused at two particle streams near the two side walls of the microchannel. Particles of different sizes can then be completely separated. Particle separation with this device was demonstrated using 7.32 μm and 15.5 μm micro particles. Experiments show that in comparison with the prior multi-orifice flow fractionation microchannel and multistage-multiorifice flow fractionation microchannel, this device can completely separate two-size particles with narrower particle stream band and larger separation distance between particle streams. In addition, it requires no sheath flow and complex multi-stage separation structures, avoiding the dilution of analyte sample and complex operations. The device has potentials to be used for continuous, complete particle separation in a variety of lab-on-a-chip and biomedical applications.Biomicrofluidics 03/2014; 8(2):024108. · 3.77 Impact Factor