Microfluidic Modeling of Circulating Leukocyte Deformation

Analysis of Leukocyte Behaviors on Microfluidic Chips

The orchestration of massive leukocytes in the immune system protects humans from invading pathogens and abnormal cells in the body. So far, researches focusing on leukocyte behaviors are performed based on both in vivo and in vitro models. The in vivo animal models are usually less controllable due to their extreme complexity and nonignorable species issue. Therefore, many researchers turn to in vitro models. With the advances in micro/nanofabrication, the microfluidic chip has emerged as a novel platform for model construction in multiple biomedical research fields. Specifically, the microfluidic chip is used to study leukocyte behaviors, due to its incomparable advantages in high throughput, precise control, and flexible integration. Moreover, the small size of the microstructures on the microfluidic chip can better mimic the native microenvironment of leukocytes, which contributes to a more reliable recapitulation. Herein are reviewed the recent advances in microfluidic chip-based leukocyte behavior analysis to provide an overview of this field. Detailed discussions are specifically focused on host defense against pathogens, immunodiagnosis, and immunotherapy studies on microfluidic chips. Finally, the current technical challenges are discussed, as well as possible innovations in this field to improve the related applications.

A circular cross-section PDMS microfluidics system for replication of cardiovascular flow conditions

Since the inception of soft lithography, microfluidic devices for cardiovascular research have been fabricated easily and cost-effectively using the soft lithography method. The drawback of this method was the fabrication of microchannels with rectangular cross-sections, which did not replicate the circular cross-sections of blood vessels. This article presents a novel, straightforward approach for the fabrication of microchannels with circular cross-sections in poly(dimethylsiloxane) (PDMS), using soft lithography. The method exploits the polymerization of the liquid silicone oligomer around a gas stream when both of them are coaxially introduced in the microchannel with a rectangular cross-section. We demonstrate (i) the ability to control the diameter of circular cross-sections of microchannels from ca. 40-100 mum; (ii) the fabrication of microchannels with constrictions, and (iii) the capability to grow endothelial cells on the inner surface of the microchannels.