bims-miftum 2020-07-19 papers

Issue of 2020–07–19
four papers selected by
Nidhi Menon, Virginia Tech

Micromachines (Basel). 2020 Jul 09. pii: E669. [Epub ahead of print]11(7):

Quantitative Image-Based Cell Viability (QuantICV) Assay for Microfluidic 3D Tissue Culture Applications.

Louis Jun Ye Ong, Liang Zhu, Gabriel Jenn Sern Tan, Yi-Chin Toh.

Microfluidic 3D tissue culture systems are attractive for in vitro drug testing applications due to the ability of these platforms to generate 3D tissue models and perform drug testing at a very small scale. However, the minute cell number and liquid volume impose significant technical challenges to perform quantitative cell viability measurements using conventional colorimetric or fluorometric assays, such as MTS or Alamar Blue. Similarly, live-dead staining approaches often utilize metabolic dyes that typically label the cytoplasm of live cells, which makes it difficult to segment and count individual cells in compact 3D tissue cultures. In this paper, we present a quantitative image-based cell viability (QuantICV) assay technique that circumvents current challenges of performing the quantitative cell viability assay in microfluidic 3D tissue cultures. A pair of cell-impermeant nuclear dyes (EthD-1 and DAPI) were used to sequentially label the nuclei of necrotic and total cell populations, respectively. Confocal microscopy and image processing algorithms were employed to visualize and quantify the cell nuclei in the 3D tissue volume. The QuantICV assay was validated and showed good concordance with the conventional bulk MTS assay in static 2D and 3D tumor cell cultures. Finally, the QuantICV assay was employed as an on-chip readout to determine the differential dose responses of parental and metastatic 3D oral squamous cell carcinoma (OSCC) to Gefitinib in a microfluidic 3D culture device. This proposed technique can be useful in microfluidic cell cultures as well as in a situation where conventional cell viability assays are not available.

Keywords: 3D cell culture; cell viability; microfluidic; quantitative; tissue culture

DOI: https://doi.org/10.3390/mi11070669

Lab Chip. 2020 Jul 14.

HepaChip-MP - a twenty-four chamber microplate for a continuously perfused liver coculture model.

HepaChip microplate (HepaChip-MP) is a microfluidic platform comprised of 24 independent culture chambers with continuous, unidirectional perfusion. In the HepaChip-MP, an automated dielectrophoresis process selectively assembles viable cells into elongated micro tissues. Freshly isolated primary human hepatocytes (PHH) and primary human liver endothelial cells (HuLEC) were successfully assembled as cocultures aiming to mimic the liver sinusoid. Minimal quantities of primary human cells are required to establish micro tissues in the HepaChip-MP. Metabolic function including induction of CYP enzymes in PHH was successfully measured demonstrating a high degree of metabolic activity of cells in HepaChip-MP cultures and sufficient sensitivity of LC-MS analysis even for the relatively small number of cells per chamber. Further, parallelization realized in HepaChip-MP enabled the acquisition of dose-response toxicity data of diclofenac with a single device. Several unique technical features should enable a widespread application of this in vitro model. We have demonstrated fully automated preparation of cell cultures in HepaChip-MP using a pipetting robot. The tubeless unidirectional perfusion system based on gravity-driven flow can be operated within a standard incubator system. Overall, the system readily integrates in workflows common in cell culture labs. Further research will be directed towards optimization of media composition to further extend culture lifetime and study oxygen gradients and their effect on zonation within the sinusoid-like microorgans. In summary, we have established a novel parallelized and scalable microfluidic in vitro liver model showing hepatocyte function and anticipate future in-depth studies of liver biology and applications in pre-clinical drug development.

DOI: https://doi.org/10.1039/d0lc00357c

Materials (Basel). 2020 Jul 10. pii: E3076. [Epub ahead of print]13(14):

Femtosecond Laser-Based Integration of Nano-Membranes into Organ-on-a-Chip Systems.

Liubov Bakhchova, Linas Jonušauskas, Dovilė Andrijec, Marharyta Kurachkina, Tomas Baravykas, Alexey Eremin, Ulrike Steinmann.

Organ-on-a-chip devices are gaining popularity in medical research due to the possibility of performing extremely complex living-body-resembling research in vitro. For this reason, there is a substantial drive in developing technologies capable of producing such structures in a simple and, at the same time, flexible manner. One of the primary challenges in producing organ-on-chip devices from a manufacturing standpoint is the prevalence of layer-by-layer bonding techniques, which result in limitations relating to the applicable materials and geometries and limited repeatability. In this work, we present an improved approach, using three dimensional (3D) laser lithography for the direct integration of a functional part-the membrane-into a closed-channel system. We show that it allows the freely choice of the geometry of the membrane and its integration into a complete organ-on-a-chip system. Considerations relating to sample preparation, the writing process, and the final preparation for operation are given. Overall, we consider that the broader application of 3D laser lithography in organ-on-a-chip fabrication is the next logical step in this field's evolution.

Keywords: adaptable membranes; femtosecond laser; microfluidic channel; organ-on-a-chip; poly-dimethyl siloxane (PDMS)

DOI: https://doi.org/10.3390/ma13143076

Biomed Microdevices. 2020 Jul 13. 22(3): 48

Microfluidic Chip based direct triple antibody immunoassay for monitoring patient comparative response to leukemia treatment.

Kutay İçöz, Ünal Akar, Ekrem Ünal.

We report a time and cost-efficient microfluidic chip for screening the leukemia cells having three specific antigens. In this method, the target blast cells are double sorted with immunomagnetic beads and captured by the 3rd antibody immobilized on the gold surface in a microfluidic chip. The captured blast cells in the chip were imaged using a bright-field optical microscope and images were analyzed to quantify the cells. First sorting was performed with nano size immunomagnetic beads and followed by 2nd sorting where micron size immunomagnetic beads were used. The low-cost microfluidic platform is made of PMMA and glass including micro size gold pads. The developed microfluidic platform was optimized with cultured B type lymphoblast cells and tested with the samples of leukemia patients. The 8 bone marrow samples of 4 leukemia patients on the initial diagnosis and on the 15th day after the start of the chemotherapy treatment were tested both with the developed microfluidic platform and the flow cytometry. A 99% statistical agreement between the two methods shows that the microfluidic chip is able to monitor the decrease in the number of blast cells due to the chemotherapy. The experiments with the patient samples demonstrate that the developed system can perform relative measurements and have a potential to monitor the patient response to the applied therapy and to enable personalized dose adjustment.

Keywords: Biochip; Direct triple antibody; Immunoassay; Leukemia; Magnetic micro/nano particles; Microfluidic -based monitoring; comparative response

DOI: https://doi.org/10.1007/s10544-020-00503-6