Grafting of choroid plexus ependymal cells promotes the growth of regenerating axons in the dorsal funiculus of rat spinal cord: a preliminary report

Nerve regeneration in the central nervous system has been studied by grafting various tissues and cells. In the present study, we demonstrated that choroid plexus ependymal cells can promote nerve regeneration when grafted into spinal cord lesions. The choroid plexus was excised from the fourth ventricle of adult rats (Wistar), minced into small fragments, and grafted into the dorsal funiculus at the C2 level in adult rat spinal cord from the same strain. Electron microscopy and fluorescence histochemistry showed that ependymal cells of the grafted choroid plexus intimately interacted with growing axons, serving to support the massive growth of regenerating axons. CGRP-positive fibers closely interacted with grafted ependymal cells. HRP injection at the sciatic nerve showed that numerous HRP-labeled regenerating fibers from the fasciculus gracilis extended into the graft 7 days after grafting. This regenerating axons from the fasciculus gracilis was maintained for at least 10 months, with some axons elongating rostrally into the dorsal funiculus. Evoked potentials of long duration were recorded at a level ca. 5 mm rostral to the lesion in the rats 8 to 10 months after grafting. These findings indicate that choroid plexus ependymal cells have the ability to facilitate axonal growth in vivo, suggesting that they may be a promising candidate as graft for the promotion of nerve regeneration in the spinal cord.