Scale-up toward clinically significant dimensions has been partially completed.

Progress has been made in continuing research on scaffolds for the guided growth of nerves to replace damaged ones. The scaffolds contain pores that are approximately cylindrical and parallel, with nearly uniform widths ranging from tens to hundreds of microns. At the earlier stage of development, experimental scaffolds had been made from agarose hydrogel. Such a scaffold was made in a multistep process in which poly(methyl methacrylate) [PMMA] fibers were used as templates for the pores. The process included placement of a bundle of the PMMA fibers in a tube, filling the interstices in the tube with a hot agarose solution, cooling to turn the solution into a gel, and then immersion in acetone to dissolve the PMMA fibers. The scaffolds were typically limited to about 25 pores per scaffold, square cross sections of no more than about 1.5 by 1.5 mm, and lengths of no more than about 2 mm.