Development and utilization of model erythrocyte and primary study of artifical erythrocyte

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We have developed a tiny particle of natural polymeric gel as a model of human red blood cell (RBC), and have made a high concentration suspension of these particles in water and physiological salt solution as a realistic model of human blood. The model RBC (MRBC) was made of alginic acid calcium gel, and was of a spherical shape and very soft and elastic. Its average diameter was about 10 μm, which was very similar to human RBC, although its shape was not so-called biconcave. It was shown that the relationships between shear rate dγ/dt and shear stress τ for the human blood with 45% hematocrit (volumetric concentration) of the RBC at the temperature of 37℃ and for the model blood with 45% hematocrit of the MRBC at the temperature of 15℃ agreed with each other very well on the Casson's diagram, i.e. the square root of dγ/dt versus √τ. The coefficients of viscosity calculated from the above diagram in the case of several different concentrations and temperatures showed clear shear thinning, and agreed very well with that of the human blood. The motion of each MRBC in the various range of shear rate was observed using a rheoscope system consisted of an inverted microscope, a cone-plate viscometer, and a high-speed video camera. As a result, in the region of low shear rate less than about 100/sec, MRBC was seen to form aggregates, which was a very similar phenomenon as real RBC forms a rouleaux when shear rate is lower than about 100/sec. The elasticity of the MRBC was also visualized and measured using a micromanipulator. The relationship between the deformation of the spherical MRBC and the force applied on it obeyed the Hertz's contact theory, and the total Young's modulus of the MRBC was 0.075MPa for ν= 0.5 and 0.lOMPa for ν= O, where ν is the Poisson's ratio. These numerical values were almost same as those of gelatin.