Development of mammalian cell-enclosing calcium-alginate hydrogel fibers in a co-flowing stream

A jetting technique in a liquid-liquid co-flowing stream was applied to the preparation of mammalian cell-enclosing calcium-alginate (Ca-alg) hydrogel fibers of several hundred micrometers in cross-sectional diameter. One percent alginate aqueous solution was extruded from needles (270, 480, 940 μm inner diameter) into a co-flowing laminar stream of 100 mM aqueous calcium chloride solution. The extruded alginate solution was stretched by the CaCl ₂ solution, which is known as a "jetting process" , and the Ca-alg hydrogel fibers were formed by gelation of the alginate solution through the uptake of calcium ions in the CaCl ₂ solution. The cross-sectional diameter of the hydrogel fibers could be controlled from approximately 100-800 μm by changing the velocities of the alginate and CaCl ₂ solution, and the inner diameter of the needle. Approximately 95% of bovine carotid artery vascular endothelial cells remained alive after the process of preparing hydrogel fibers in a co-flowing stream, demonstrating that the cell-enclosing process scarcely influences the viability of the enclosed cells.