Engineering approaches to the microcirculation studies

This review focused on a few methodologies which the author, with a background of chemical engineering, has developed in the physiological studies of microcirculation. (1) Fluorescent tracers to visualize mass transfer and hemodynamics: By means of a high sensitive SIT camera equipped in an intravital microscope system, dynamic processes of the permeation of a fluorescent dye from the microvessels through the extravascular space to lymphatics was made to be visualized. Dynamic behaviors of the formed elements were also quantitatively analyzed by the selective fluorescent labeling technique. (2) The dye/light method to induce platelet thrombus in vivo: Intravascular platelet aggregation and subsequent thrombus formation leading to the complete occlusion of the vessels were produced in the microvasculature by the irradiation of filtered light in combination with the intravascular administration of sodium fluorescein. This method enables quantitative evaluation of thrombus formation process in terms of thrombus formation times. Effects of hemodynamic parameters on thrombogenesis in vivo were quantitatively analyzed. (3) Establishment of peritoneal disseminated tumor model: Colon tumor cells (RCN-9) were inoculated into the peritoneal cavity of male Fischer rats, and the intravital microscopic observation of angiogenic vascular growth accompanying tumor growth was made possible. Dynamic behavior of leukocytes in the microcirculation of solid tumor tissue was visualized using a fluorescent labeling technique combined with the use of a real-time confocal laser-scanning microscope.