In vitro formation and characterization of a perfusable three-dimensional tubular capillary network in microfluidic devices.

This paper describes the in vitro formation and characterization of perfusable capillary networks made of human umbilical vein endothelial cells (HUVECs) in microfluidic devices (MFDs). Using this platform, an array of three-dimensional (3D) tubular capillaries of various dimensions (50-150 µm in diameter and 100-1600 µm in length) can be formed reproducibly. To generate connected blood vessels, MFDs were completely filled with fibrin gel and subsequently processed to selectively leave behind gel structures inside the bridge channels. Following gel solidification, HUVECs were coated along the gel walls, on opposite ends of the patterned 3D fibrin gel. After 3-4 days, HUVECs migrating into the fibrin gel from opposite ends fused with each other, spontaneously forming a connected vessel that expressed tight junction proteins (e.g., ZO-1), which are characteristic of post-capillary venules. With ready access to a perfusable capillary network, we demonstrated perfusion of the vessels and imaged red blood cells (RBCs) and beads flowing through them. The results were reproducible (∼50% successful perfusable capillaries), consistent, and could be performed in a parallel manner (9 devices per well plate). Additionally, compatibility with high resolution live-cell microscopy and the possibility of incorporating other cell types makes this a unique experimental platform for investigating basic and applied aspects of angiogenesis, anastomosis, and vascular biology.

Novel microfluidic platform for culturing neurons: culturing and biochemical analysis of neuronal components.

Neurons, one of the most polarized types of cells, are typically composed of cell bodies (soma), dendrites, and axons. Many events such as electric signal transmission, axonal transport, and local protein synthesis occur in the axon, so that a method for isolating axons from somata and dendrites is required for systematically investigating these axonal events. Based on a previously developed neuron culture method for isolating and directing the growth of central nervous system axons without introducing neutrophins, we report three modified microfluidic platforms: (1) for performing biochemical analysis of the pure axonal fraction, (2) for culturing tissue explants, and (3) a design that allows high content assay on same group of cells. The key feature of these newly developed platforms is that the devices incorporate a number of microgrooves for isolating axons from the cell body. They utilize an open cellculture area, unlike the enclosed channels of the previous design. This design has extended the axonal channel so that a sufficient amount of pure axonal fraction can be obtained to perform biochemical analysis. The design also addresses the drawback of the previous neuron culture device, which was not adaptable for culturing thick neuronal tissues such as brain explants, neurospheres, and embryoid bodies, which are essential model tissues in neuroscience research. The design has an open cellculture area in the center and four enclosed channels around open area, and is suitable for multiple drug screening assays.