ABSTRACT
Transected dorsal root axons of adult rats can be induced to regenerate through the normally non-permissive environment of the dorsal root entry zone (DREZ) into the spinal cord by implanting enteric glia (EG) into the DREZ. We have now examined whether the regenerating central axons make functional connections by studying the return of function of a behavioral response, the cutaneous trunci muscle (CTM) reflex. Implantation of EG into the spinal cord DREZ led to functional recovery of the CTM reflex in 82%, 72% and 70% of animals 1, 2 and 3 months, respectively, after injury. In contrast, the CTM reflex did not recover in animals implanted with 3T3 or C6 glioma cells or with vehicle only.
Subject(s)
Muscle Contraction/physiology , Neuroglia/physiology , Recovery of Function , Skin/innervation , Spinal Cord Injuries/physiopathology , 3T3 Cells/physiology , 3T3 Cells/transplantation , Animals , Carbocyanines/pharmacokinetics , Cells, Cultured , Female , Fluorescent Dyes/pharmacokinetics , Glial Fibrillary Acidic Protein/metabolism , Immunohistochemistry , Intestines , Mice , Neuroglia/transplantation , Rats , Rats, Wistar , Spinal Nerve Roots/metabolism , Spinal Nerve Roots/pathology , Spinal Nerve Roots/physiopathology , Time Factors , Transplantation/methods , Tumor Cells, Cultured/physiology , Tumor Cells, Cultured/transplantationABSTRACT
After spinal cord injury axonal regeneration is poor, but may be enhanced by the implantation of olfactory ensheathing glia (OEG). Enteric glia (EG) share many properties of OEG. Transected dorsal root axons normally do not regenerate through the central nervous system myelin into the spinal cord. We tested whether EG, like OEG, could promote regeneration in this paradigm. Three weeks after EG implantation, numerous regenerating dorsal root axons reentered the spinal cord. Ingrowth of dorsal root axons was observed using 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate. Primary sensory afferents invaded laminae 1, 2, and 3, grew through laminae 4 and 5, and reached the dorsal gray commissure. No axonal ingrowth was observed in control animals, indicating that transplanted EG enabled regeneration of the injured dorsal root axons into the adult spinal cord. Thus, EG implantation may be beneficial in promoting axonal growth after central nervous system injury.
