Demyelination of axons resulted in distinct reduction of conduction velocity or block of conduction. Remyelination by transplantation of myelin-forming cells may provide a therapeutic approach for demyelinated diseases. However, which cell type will be the most appropriate candidate for such a cell therapy is not established. To investigate how effective grafted neonatal brain cell (BC) (including oligodendrocyte and astrocyte) isolated from neonatal fronto-temporal lobes, adult olfactory ensheathing cell (OEC) or adult Schwann cell (SC) may be for demyelinated CNS axons in vivo, dorsal columns(DCs) of adult rat spinal cord were demyelinated at Th 11 by X-ray irradiation (day 0) and the injection of ethidium bromide (day 3), and transplanted 5 x 10(4) of BCs, 3 x 10(4) of OECs, or 3 x 10(4) of SCs into the lesion (day 6). Day 28-31, spinal cord were removed and transferred an in vitro recording chamber to record field potentials using glass micropipettes, to investigate conduction properties at 36 degrees. Normal DCs were recorded in same manner. Histological examination revealed that OECs and SCs resulted in substantial SC-like patterns of remyelination to equal degree, BC transplantation resulted in less myelination. The conduction velocities were significantly improved to 4.2 +/- 2.4 m/s(BC, n = 5), 8.5 +/- 3.3 m/s(OEC, n = 6) and 7.7 +/- 1.5 m/s(SC, n = 5), compared to demyelinated axons(1.2 +/- 0.4 m/s, n = 7). A 600 Hz 0.5 sec stimulus train led to an amplitude decrement of 7.1 +/- 7.5% (n = 7) in demyelinated axons. Following transplantation, the amplitude decreased in 31.3 +/- 18.7% (BC, n = 5), 49.9 +/- 19.9% (OEC, n = 6) and 66.2 +/- 11.9% (SC, n = 5). Transplanted OECs and SCs enhanced the remyelination of demyelinated CNS axons, and improved conduction properties were similar, and more effective than that induced from isolated CNS tissue which included oligodendrocyte.