1. A method for producing an engineered tissue scaffold for neural repair, the method comprising: i) providing a cell guide comprising a hydrogel matrix seeded with tension-generating cells, the matrix being tethered at opposed first and second ends to a frame; ii) allowing the tension-generating cells to generate tension within the matrix, such that the cells self-align within the matrix; and iii) removing liquid from the hydrogel matrix in order to at least partially dehydrate the matrix to form a sheet while retaining cells within the matrix; thereby providing an engineered tissue scaffold, wherein the tension-generating cells are not Schwann cells, but are stem cells capable of differentiating into cells having Schwann-cell-like properties, or are derived from such stem cells.