Creating vascular networks in tissues is crucial for tissue engineering. Although recent studies have demonstrated the formation of vessel-like structures in a tissue model, long-term culture is still challenging due to the lack of active perfusion in vascular networks. Here, we present a method to create a three-dimensional cellular spheroid with a perfusable vascular network in a microfluidic device. By the definition of the cellular interaction between human lung fibroblasts (hLFs) in a spheroid and human umbilical vein endothelial cells (HUVECs) in microchannels, angiogenic sprouts were induced from microchannels toward the spheroid; the sprouts reached the vessel-like structures in a spheroid to form a continuous lumen. We demonstrated that the vascular network could administer biological substances to the interior of the spheroid. As cell density in the spheroid is similar to that of a tissue, the perfusable vasculature model opens up new possibilities for a long-term tissue culture in vitro.

Blood vessel morphology is dictated by mechanical and biochemical cues. Among these, flow-induced shear stress and pericytes have been studied using an on-chip vascular network, for understanding the relationship between...

Microelectrode arrays (MEAs) are very powerful sensor devices for the non-invasive measurement of extracellular field potentials from excited cells. In this study, new types of interfaces were developed on MEAs by exploiting the electrochemical polymerization of conducting polymers with biomolecules. The composite films were composed of poly(3,4-ethylenedioxythiophen) (PEDOT) and anionic polysaccharide (gellan gum). The PEDOT/biomolecule composite films had no cytotoxic effect, and reduced the electrode impedance at 1 kHz to 8.84 + 0.50 kΩ. This biointerface enabled us to record extracellular field potentials derived from the spontaneous beating of cardiomyocytes.

An estimation model of farm field irrigation water demand is developed. The model is based on the lamped kinemtic wave model considering soil water balance. The lamped model approach reduces the computational load in rainfall-runoff analysis and allows application to large river basins. Evapotranspiration is estimated on hourly basis by the improvement of FAO's method. Not only water volume necessary for farm field irrigation but also the number of the water charge and its interval can be estimated by the combined use of the lamped runoff model and the hourly evapotranspiration model.