IMPLANTATION OF STIMULATED HOMOLOGOUS MACROPHAGES RESULTS IN PARTIAL RECOVERY OF PARAPLEGIC RATS

Postinjury recovery in most tissues requires an effective dialog with macrophages; however, in the mammalian central nervous system, this di alog may be restricted (possibly due to its immune-privileged status), which probably contributes to its regeneration failure. We circumvent ed this by implanting macrophages, pre-exposed ex vivo to peripheral n erve segments, into transected rat spinal cord. This stimulated tissue repair and partial recovery of motor function, manifested behaviorall y by movement of hind limbs, plantar placement of the paws and weight support, and electrophysiologically by cortically evoked hind-limb mus cle response. We substantiated these findings immunohistochemically by demonstrating continuity of labeled nerve fibers across the transecte d site, and by tracing descending fibers distally to it by anterograde labeling. In recovered rats, re-transection of the cord above the pri mary transection site led to loss of recovery, indicating the involvem ent of long descending spinal tracts. Injection of macrophages into th e site of injury is relatively non-invasive and, as the cells are auto logous, it may be developed into a clinical therapy.