Cultured, Autologous Nucleus Pulposus Cells Induce Functional Changes in Spinal Nerve Roots

STUDY DESIGN Nerve conduction velocity in pig nerve roots was assessed after application of various preparations of nucleus pulposus and control. OBJECTIVE To study whether cultured nucleus pulposus cells could reduce nerve conduction velocity after epidural application. SUMMARY OF BACKGROUND DATA It is known that nucleus pulposus applied epidurally may reduce the nerve conduction velocity of the adjacent nerve roots and that this reduction seems to be related to the cells of the nucleus pulposus. METHODS Nucleus pulposus cells and fibroblasts were cultured for 3 weeks, and various preparations were applied to the cauda equina in 29 pigs. The cells were always from the same animals from which they had been harvested. After 1 week, nerve conduction velocity was determined by local electrical stimulation. RESULTS Application of live fibroblasts and conditioned culture medium from the nucleus pulposus cell culture dishes did not induce significant reduction of conduction velocity, compared with application of dead fibroblasts, which served as control. However, application of live and dead nucleus pulposus cells induced significant reductions. CONCLUSIONS Application of nucleus pulposus cells reproduced the previously seen reduction in nerve conduction velocity induced by nonmodified nucleus pulposus. Because membranes of the nucleus pulposus cells had similar effects, it can be assumed that the effects are related to membrane-bound substances or structures.