Gel Microrods for 3D Tissue Printing.

Large scale 3D ordering of anisotropic gel objects, such as gel microrods, both rigid and soft, is in demand for the engineering of replica tissues but has not yet been achieved. Here, monodisperse gel microrods of gelatin methacrylate (GelMa) or Matrigel are generated by a droplet-based microfluidics tubing system. The microrods are 50-300 µm wide and 1-3 mm long; the GelMa versions are produced at up to 50 s-1 while the more fragile Matrigel versions are produced at up to 10 s-1 followed by 1 h of gelation. Upon ejection from the tubing, the rods can be printed into robust 3D structures of centimeter dimensions in which the rods are organized into patterns, including various parallel arrangements and tubular structures. Further, mammalian cells contained within the microrods remain viable, and can proliferate and migrate. As well as homogeneous microrods, Janus and ternary rods can be prepared. Gel microrods will be useful for the production of printed tissues, which mimic intricate architectures found in Nature that cannot presently be attained.