Session: 13-04-02: Applications of Micro and Nano Systems in Medicine and Biology II

Paper Number: 112515

112515 - Deformation of Cells Passing Through Gaps Between Microcylinders in Channel 

A gap takes important role of sorting cells in vivo. Some cells deform to pass through a very narrow gap. The mode of deformation of each cell can be related to its biological function. An erythrocyte passes through the microcirculatory system. It deforms from the biconcave disk to the parachute shape to pass through capillaries. According to aging, both the deformation limit and deformation sensitivity of erythrocytes decrease. After circulating through the blood vessels for several days, erythrocytes are trapped in the microcirculatory system. One of the systems that traps erythrocytes is the spleen. The spleen has a special morphological pathway for classifying damaged erythrocytes. A leucocyte can pass through a very narrow gap in vivo.

The condition of cells can be checked by examining their deformability. Deformation of an erythrocyte is measured in various ways: microscopic photography of capillaries in vivo, suction to a capillary in vitro, and deformation in shear flow with a rheoscope in vitro. Deformability of a cell is related to the elasticity of the endoskeleton and membrane.

Micromachining technique realizes micro-topography of the surface of micro-flowchannels. The technique is available to several applications: simulation of the morphology of microcirculation, and manipulation of cells for diagnostics in vitro. Several structures for tests on biological cells were made in previous studies. In the previous study, gaps between parallel walls were designed by combining micro-topography of plates. Since the passage distance is long in the channel, the cell cannot pass unless the entire cell is flattened. In addition, deformation in the vertical direction cannot be observed. It is also difficult to observe the partial deformation.

To observe the deformation of the cell in the depth direction between the plates, another type of gap was designed. In this study, gaps between microcylinders were designed to observe partial deformation of cells. Controlled dimension of the gap enables quantitative analysis of deformability of each cell. In the gap, deformation of each cell has been analyzed. The dimension of each microcylinder is as follows: 25 µm diameter, and 60 µm height.

Microcylinders are arranged along the four lines by the photolithography technique. Each line is perpendicular to the flow direction of the channel. The pitch of lines is 0.5 mm. Each line has its own uniform gaps (25 µm, 20 µm, 15 µm and 10 µm) between microcylinders. The micro-gaps are located at the middle part of the channel, of which dimension of the cross section has 1 mm width, 30 mm length and 60 µm height. The channel is constructed between parallel plates: the upper plate of polydimethylsiloxane (PDMS), and the lower plate of glass.

Myoblasts (C2C12: mouse myoblast cell line) sparsely suspended in the medium were used for the test. The cell passing through the slit was observed by the microscope, and recorded by the video camera. At the two-dimensional image, the contour of each cell was traced and analyzed by “ImageJ”. The projected two-dimensional area of each cell was calculated. The deformation direction ratio was calculated by the projected length of the flow direction and the direction perpendicular to the flow. The contour was approximated to an ellipse. The centroid of the ellipse was used to track the movement of each flowing cell. On the ellipse, the shape index was calculated by the length of the major axis, and the minor axis.

The experimental results show that each cell is elongated to the flow direction with decrease of two-dimensional area during passing through the gap. The designed gaps have capability for evaluation of cell deformation.

Presenting Author: Shigehiro Hashimoto Kogakuin University

Presenting Author Biography: 1972-1975 Tokyo Gakugei University Senior High School, Tokyo, Japan.
1975-1979 Bachelor of Engineering, Department of Mechanical Physics, School of Engineering, Tokyo Institute of Technology, Tokyo, Japan.
1977 Internship Student (from July to August), Research Center for Artificial Heart, Free University in Berlin, Berlin, Germany.
1979-1981 Master of Engineering, Mechanical Engineering, Graduate School of Science and Engineering, Tokyo Institute of Technology, Tokyo, Japan.
1987 Doctor of Medicine at Kitasato University, Sagamihara, Japan.
1990 Doctor of Engineering at Tokyo Institute of Technology, Tokyo, Japan.

Professional experience:
1981-1989 Research Associate, School of Medicine, Kitasato University, Sagamihara, Japan.
1989-1994 Assistant Professor, School of Medicine, Kitasato University, Sagamihara, Japan.
1994-2001 Associate Professor, Department of Electronics, School of Engineering, Osaka Institute of Technology, Osaka, Japan.
2001-2004 Professor, Department of Electronics, School of Engineering, Osaka Institute of Technology, Osaka, Japan.
2004-2006 Professor, Department of Electronics, Information and Communication Engineering, School of Engineering, Osaka Institute of Technology, Osaka, Japan.
2004-2005 Chair, Department of Electronics, Information and Communication Engineering, School of Engineering, Osaka Institute of Technology, Osaka, Japan.
2005-2009 Director, Medical Engineering Research Center, Osaka Institute of Technology, Osaka, Japan.
2005-2006 Coordinator, Department of Biomedical Engineering, School of Engineering, Osaka Institute of Technology, Osaka, Japan.
2006-2011 Professor, Department of Biomedical Engineering, School of Engineering, Osaka Institute of Technology, Osaka, Japan.
2011- Professor, Department of Mechanical Engineering, School of Engineering, Kogakuin University, Tokyo, Japan.
2012-2018 Associate to President and Dean of Admissions Center, Kogakuin University, Tokyo, Japan.
2017-2020 Councilor, Kogakuin University, Tokyo, Japan.
2018-2021 Dean, School of Engineering, Kogakuin University, Tokyo, Japan.
2020-2021 Chair, Systems Design, Graduate School of Engineering, Kogakuin University, Tokyo, Japan.

2021-2023 The Society of Life Support Engineering, Japan (President).
2022-2025 Associate Editor ASME Journal of Engineering and Science in Medical Diagnostics and Therapy

Authors:

Shigehiro Hashimoto Kogakuin University
Shogo Uehara Kogakuin University
Kota Yamamoto Kogakuin University