PROMOTION OF REGENERATION AND AXON GROWTH FOLLOWING INJURY IN AN INVERTEBRATE NERVOUS-SYSTEM BY THE USE OF 3-DIMENSIONAL COLLAGEN GELS

We describe the application of three-dimensional collagen matrices to the study of nerve cord repair in the leech. Our experiments show that ganglia and connectives of the leech ventral nerve cord can be mainta ined for up to four weeks embedded in 3D gels constructed from mammali an type 1 collagen. Severed nerve cords embedded in the collagen gel r eliably repaired within a few days of culture. The gel was penetrable by cells emigrating from the cut ends of nerves and connectives, and w e consistently saw regenerative outgrowth of severed peripheral and ce ntral axons into the gel matrix. Thus, 3D gels provide an in vitro sys tem in which we can reliably obtain repair of severed nerve cords in t he dish, and visualize cell behaviour underlying regenerative growth a t the damage site and which offers the possibility of manipulating the regenerating cells and their extracellular environment in various way s at stages during repair. Using this system it should be possible to test the effect on the repair process of altering expression of select ed genes in identified nerve cells.