High-throughput acoustofluidic microchannels for single cell rotation

There is a growing desire for cell rotation in the field of biophysics, bioengineering and biomedicine. We herein present novel microfluidic channels for simultaneous high-throughput cell self-rotation using local circular streaming generated by ultrasonic wave excited bubble arrays. The bubble traps achieve high homogeneity of liquid-gas interface by setting capillary valves at the entrances of dead-end bubble trappers orthogonal to the main microchannel. In such a highly uniform bubble array, rotation at different fields of bubble-relevant vortices is considered equal and interconvertible. The device is compatible with cells of various size and retains manageable rotation velocity when actuated by signals of varying frequency and voltage. Experimental observations were confirmed consistent with theoretical estimation and numerical simulation. Comparing with the conventional approaches of cell rotation, our device has multiple merits such as high throughput, low cost and simple fabrication procedure, and high compatibility for lab-on-chip integration. Therefore, the platform holds a promise in cell observation, medicine development and biological detection.

KIF5B modulates central spindle organization in late-stage cytokinesis in chondrocytes

Background The growth plate is a special region of the cartilage that drives longitudinal growth of long bones. Proliferating chondrocytes in the growth plate, arranged in columns, divide perpendicular to the long axis of the growth plate then intercalate to re-align with parental columns. Which molecular partners maintain growth plate columnar structures and chondrocyte cytokinesis has not been fully revealed. It is reported that kinesin family member 3A (KIF3A), a subunit of kinesin-2, plays an important role in maintaining columnar organization in growth plates via controlling primary cilia formation and cell proliferation. Result Here we identify kinesin family member 5B (KIF5B), the heavy chain of kinesin-1, a ubiquitously expressed motor protein for anterograde intracellular transport along the microtubule network, as a key modulator of cytokinesis in chondrocytes via maintenance of central spindle organization. We show that KIF5B is concentrated in the central spindle during cytokinesis in both primary chondrocytes and chondrogenic ATDC5 cells. Conclusion The failure of cytokinesis in KIF5B null chondrocytes leads to incomplete cell rotation, disrupting proliferation and differentiation, and results in a disorganized growth plate.

Dual-Mode Circular Polarization Selective Surface Cell for Single-Layer Dual-Band Circularly Polarized Reflectarray

A dual-mode circular polarization selective surface (CPSS) cell based on a modification of the Pierrot cell is presented for single-layer dual-band circularly polarized (CP) reflectarray antenna design. To achieve dual-mode CP discrimination performance, the improved three-dimensional geometry and the high-order resonances of the CPSS cell are utilized. The required phase shifts in both modes are obtained by varying the cell rotation angle. A single-layer dual-band reflectarray operating with orthogonal CPs has been fabricated and tested. Measured results show the peak gains of 25.2 dBi at 11.6 GHz with 31% 3 dB axial ratio (AR) bandwidth and 26.5 dBi at 14.6 GHz with 32% 3 dB AR bandwidth, respectively. The measured efficiency is 41.2% at 11.6 GHz and 55.5% at 14.6 GHz.

Deep-Learning-Based Polar-Body Detection for Automatic Cell Manipulation

Polar-body detection is an essential and crucial procedure in various automatic cell manipulations. The polar body can only be observed when it is located near the focal plane of the microscope, so we need to detect the polar body during cell rotation in cell manipulations. However, three-dimensional cell rotation by micropipette causes polar-body defocus and cell/polar-body deformation, which have not been discussed in existing image-level polar-body-detection approaches. Moreover, varying sizes of the polar bodies increase the difficulty of polar-body detection. In this paper, we propose a deep-learning-based framework to realize polar-body detection in cell rotation. The detection problem is interpreted as image segmentation, which separates the polar body from the background. Then, we improve U-net, which is a typical convolutional neural network (CNN) for medical-image segmentation, so that the network can be applied to polar-body detection, especially for the detection of defocused polar bodies and polar bodies of different sizes. For CNN training, we also designed a particular image-transformation method to simulate more cell-rotation situations, including cell- and polar-body deformation, so that the deformed polar body in cell rotation would be detected by the proposed method. Experiment results show that our method achieves high detection accuracy of 98.7% on a test dataset of 1000 images, and performs well in cell-rotation processes. This method can be applied to various automatic cell manipulations in the future.