Three-dimensional formation of magnetic micro-gel beads for tissue engineering

We have commenced basic research on the three-dimensional pattern formation of micro-gel beads for applications in biological tissue engineering. In this new technique, micro-gel beads are premagnetized by doping them with magnetic nanoparticles. Living cells will be included in beads for actual use. If a nonuniform magnetic field is applied to a solution containing these magnetized beads, the beads will align, contact, and form a 3D structure. The structure is controlled by the seed pattern of the magnetic particles plugged in a substrate and the profile of the magnetic field distribution. We have constructed tubes, which imitate blood vessels, for demonstration using gel beads whose diameters are of the order of several tens of micrometers. The diameter of the demonstrated tube was less than 0.5 mm and its length was 6.6 mm, although living cells were not included in the beads. Numerical calculations by using the discrete element method were conducted to confirm the formation of the tube and to predict the effect of centrifugal force, which will be applied to fill other tissues in the space between magnetically patterned beads. Although this unique technology is in the nascent stage, it can potentially be used to form threedimensional, nonuniform, and heterogeneous artificial organs for tissue engineering.