• Journal of the Korean Society for Precision Engineering
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• v.31 no.6
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• pp.521-525
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• 2014

Circulating tumor cells (CTCs) in the bloodstream of cancer patients provide an accessible source for detection, characterization, and monitoring of nonhematological cancers. The effectiveness of the CTC-Chip for the isolation of ovarian cancer cells was demonstrated by adapting the herringbone-chip (HB-Chip). The motions of the particles on the HB chip were simulated by a unique combination of buoyant, gravitational forces, and helical flows with a computational modeling. The motions of cells are demonstrated by applying polystylene bead and ovarian cancer cells into the microfabricated HB-Chip. The experimental results from beads and cells are well accordance with the simulated ones, as previously reported by Toner group. Thus, I expect that these modeling and experimental skills will play key roles in the clinical applications on CTC isolation as well as the basic research on characterization of CTCs under flow.

• International Journal of Stem Cells
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• v.17 no.1
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• pp.30-37
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• 2024

The lung is a complex organ comprising a branched airway that connects the large airway and millions of terminal gas-exchange units. Traditional pulmonary biomedical research by using cell line model system have limitations such as lack of cellular heterogeneity, animal models also have limitations including ethical concern, race-to-race variations, and physiological differences found in vivo. Organoids and on-a-chip models offer viable solutions for these issues. Organoids are three-dimensional, self-organized construct composed of numerous cells derived from stem cells cultured with growth factors required for the maintenance of stem cells. On-a-chip models are biomimetic microsystems which are able to customize to use microfluidic systems to simulate blood flow in blood channels or vacuum to simulate human breathing. This review summarizes the key components and previous biomedical studies conducted on lung organoids and lung-on-a-chip models, and introduces potential future applications. Considering the importance and benefits of these model systems, we believe that the system will offer better platform to biomedical researchers on pulmonary diseases, such as emerging viral infection, progressive fibrotic pulmonary diseases, or primary or metastatic lung cancer.

• Molecules and Cells
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• v.27 no.3
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• pp.337-343
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• 2009

We developed a novel on-chip activity assay using protein arrays for quantitative and rapid analysis of transglutaminase activity in mammalian cells. Transglutaminases are a family of $Ca^{2+}$-dependent enzymes involved in cell regulation as well as human diseases such as neurodegenerative disorders, inflammatory diseases and tumor progression. We fabricated the protein arrays by immobilizing N,N'-dimethylcasein (a substrate) on the amine surface of the arrays. We initiated transamidating reaction on the protein arrays and determined the transglutaminase activity by analyzing the fluorescence intensity of biotinylated casein. The on-chip transglutaminase activity assay was proved to be much more sensitive than the $[^3H]putrescine$-incorporation assay. We successfully applied the on-chip assay to a rapid and quantitative analysis of the transglutaminase activity in all-trans retinoic acid-treated NIH 3T3 and SH-SY5Y cells. In addition, the on-chip transglutaminase activity assay was sufficiently sensitive to determine the transglutaminase activity in eleven mammalian cell lines. Thus, this novel on-chip transglutaminase activity assay was confirmed to be a sensitive and high-throughput approach to investigating the roles of transglutaminase in cellular signaling, and, moreover, it is likely to have a strong potential for monitoring human diseases.

• Biomolecules & Therapeutics
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• v.26 no.4
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• pp.380-388
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• 2018

Neural stem cells (NSCs) have the ability to self-renew and differentiate into multiple nervous system cell types. During embryonic development, the concentrations of soluble biological molecules have a critical role in controlling cell proliferation, migration, differentiation and apoptosis. In an effort to find optimal culture conditions for the generation of desired cell types in vitro, we used a microfluidic chip-generated growth factor gradient system. In the current study, NSCs in the microfluidic device remained healthy during the entire period of cell culture, and proliferated and differentiated in response to the concentration gradient of growth factors (epithermal growth factor and basic fibroblast growth factor). We also showed that overexpression of ASCL1 in NSCs increased neuronal differentiation depending on the concentration gradient of growth factors generated in the microfluidic gradient chip. The microfluidic system allowed us to study concentration-dependent effects of growth factors within a single device, while a traditional system requires multiple independent cultures using fixed growth factor concentrations. Our study suggests that the microfluidic gradient-generating chip is a powerful tool for determining the optimal culture conditions.

• KSBB Journal
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• v.25 no.4
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• pp.344-350
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• 2010

This paper demonstrates a microfluidic chip incorporating patterned hollow silica beads that can be effectively used for chemotaxis assay. The hollow silica bead has been exploited to develop a carrier for chemoattractant to induce cell migration. The microfluidic chip contains a patterned array of microfabricated docks which can hold only one bead per docking site. The hollow bead placed inside microfluidic chip releases chemotactic reagent (PDGF-BB) around its periphery in a controlled fashion which generates a signal for chemotatic migration of fibroblast cells. The number of cells migrated close to each bead has been assessed. On-chip cell migration assay showed a remarkable result proving the high efficiency and reliable accuracy in quantitative analysis. Therefore, the device could be extensively used in cell migration assay and other various studies related to cellular movements.

• Toxicological Research
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• v.20 no.2
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• pp.109-116
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• 2004

For the safety evaluation of adenovirus-mediated gene transfer, we investigated differential gene expressions after transfecting adenoviral vector containing p16 tumor suppressor gene (Ad5CMV-p16) into human non-small cell lung cancer cells. In the previous study, we showed adenovirus-mediated $p16^{INK4a}$ gene transfer resulted in significant inhibition of cancer cell growth. We investigated gene expression changes after transfecting Ad5CMV-p16, Ad5CMV (null type, a mock vector) into A549 cells by using cDNA chip and oligonucleotide microarray chip (1200 genes) which carries genes related with signal transduction pathways, cell cycle regulations, oncogenes and tumor suppressor genes. We found that $p16^{INK4a}$ gene transfer down regulated 5 genes (cdc2, cyclin D3, cyclin B, cyclin E, cdk2) among 26 genes involved in cell cycle regulations. Compared with serum-free medium treated cells, Ad5CMV-p16 changed 27 gene expressions, two fold or more on oligonucleotide chip. In addition, Ad5CMV-p16 did not seem to increase the tumorigenicity-related gene expression in A549 cells. Further studies will be needed to investigate the effect of Ad5CMV-p16 on normal human cells and tissues for safety evaluation.

• Journal of Microbiology and Biotechnology
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• v.16 no.8
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• pp.1229-1235
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• 2006

A lab-on-a-chip (LoC) was designed for simultaneous monitoring of microorganisms, antibiotic residues, somatic cells, and pH in raw milk. The LoC was fabricated from polydimethylsiloxane (PDMS) using microelectromechanical system (MEMS) technology, which consisted of two parts; a protein array and microchannel. The protein array was fabricated by immobilizing five types of antibodies corresponding to two microorganisms, two antibiotic residues, and somatic cells. A sol-gel film was deposited on a glass substrate to immobilize the antibodies. The target analytes in raw milk could be bound with the corresponding antibody by an immunoreaction, and the antigen-antibody complex was detected using fluorescence microscopy. SNARF-dextran was used as a pH indicator, and the SNARF-entrapped hydrogel was attached to the microchannel in the chip. After injecting the milk sample into the channel, the pH was measured by monitoring the change in fluorescence intensity by fluorescence microscopy. The on-chip simultaneous assay of two microorganisms (E. coli O157:H7 and Streptococcus agalactiae), two antibiotic residues (penicillin G and dihydrostreptomycin), and neutrophils was successfully accomplished using the proposed LoC system.

• Journal of the Korea Convergence Society
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• v.9 no.3
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• pp.217-222
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• 2018

In this paper, a new micro polymer chip platform and protocol were developed for rare cell sample preparation. The proposed platform and protocol overcome the current limitation of the dilution method which is based on statistics and the FACS method which expensive and requires fluorescence staining. It allows collecting exact number of target cells simply and selectively because the cells are visually confirmed during the collecting process. The collected cells can be transported or spiked into a desired locations, such as a microchamber, without cell loss. This research may applicable not only to a rare cell sample preparation for Lab on a Chip cancer diagnosis, but also to a single/double/multiple cell sample preparation for a cell analysis field. To verify this platform and protocol, five human breast cancer cells (MCF-7) were collected and transported into a hemocytometer chamber.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.12
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• pp.1671-1674
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• 2014

This paper presents a frequency-dependent cell impedance analysis chip for use in cancer and normal cell discrimination. The previous cell impedance analysis chips for flowing cells cannot allow enough time for cell-to-electrode contact to monitor frequency-dependent impedance response. Another type of the previous cell impedance analysis chips for the cells clamped by membranes need complex sample control for making stable cell-to-electrode contact. We present a new impedance analysis chip using the microchamber array, on which a PDMS cover is placed to make stable cell-to-electrode contact for the individual cell trapped in each microchamber; thus achieving frequency-dependent single-cell impedance analysis without complex sample control. Compared to the normal cells, the magnitude of NHBE cells is $60.07{\sim}97.41k{\Omega}$ higher than A549 cells in the frequency range of 95.6 kHz~2MHz and the phase of NHBE is $3.96^{\circ}{\sim}20.8^{\circ}$ higher than A549 cells in the frequency range of 4.37 kHz~2MHz, respectively. It is demonstrated experimentally that the impedance analysis chip performs frequency-dependent cell impedance analysis by making stable cell-to-electrode contact with simple sample control; thereby applicable to the normal cell and cancer cell discrimination.

• Journal of Chest Surgery
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• v.50 no.3
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• pp.153-162
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• 2017

Background: The mesenchymal-epithelial transition factor (MET) receptor can be overexpressed in solid tumors, including small cell lung cancer (SCLC). However, the molecular mechanism regulating MET stability and turnover in SCLC remains undefined. One potential mechanism of MET regulation involves the C-terminus of Hsp70-interacting protein (CHIP), which targets heat shock protein 90-interacting proteins for ubiquitination and proteasomal degradation. In the present study, we investigated the functional effects of CHIP expression on MET regulation and the control of SCLC cell apoptosis and invasion. Methods: To evaluate the expression of CHIP and c-Met, which is a protein that in humans is encoded by the MET gene (the MET proto-oncogene), we examined the expression pattern of c-Met and CHIP in SCLC cell lines by western blotting. To investigate whether CHIP overexpression reduced cell proliferation and invasive activity in SCLC cell lines, we transfected cells with CHIP and performed a cell viability assay and cellular apoptosis assays. Results: We found an inverse relationship between the expression of CHIP and MET in SCLC cell lines (n=5). CHIP destabilized the endogenous MET receptor in SCLC cell lines, indicating an essential role for CHIP in the regulation of MET degradation. In addition, CHIP inhibited MET-dependent pathways, and invasion, cell growth, and apoptosis were reduced by CHIP overexpression in SCLC cell lines. Conclusion: C HIP is capable of regulating SCLC cell apoptosis and invasion by inhibiting MET-mediated cytoskeletal and cell survival pathways in NCI-H69 cells. CHIP suppresses MET-dependent signaling, and regulates MET-mediated SCLC motility.