An engineered three-dimensional structure includes living cells cohered with each other. The living cells suitably include Schwann cells and at least one other type of cell. The cells accompanying the Schwann cells can suitably be bone marrow stem cells or another type of cell having one or more anti-inflammatory properties. The structure is suitably a graft that facilitates restorative axon growth when the graft is implanted between the proximal and distal stubs of a severed nerve in a living organism. The graft can optionally include a plurality of acellular conduits extending between opposite axial ends of the graft. Bio-printing techniques can be used to assemble a three-dimensional construct that becomes through maturation an axon-guiding graft, by stacking a plurality of multicellular bodies, each of which includes a plurality of living cells cohered to one another to sufficiently to avoid collapsing when the multicellular bodies are stacked to form the structure.