Central nervous system transplantation benefitted by low-power laser irradiation

The effect of low-power laser irradiation on mammalian central nervous system (CNS) transplantation is reported. Fetal brain allografts were transplanted into the brain (fornix region) of 20 adult rats and spinal cord allografts were transplanted into the spinal cord of eight dogs. For 21 days, the closed operated wounds of 10 rats and four dogs were exposed daily to transcutaneous low-power laser irradiation cw HeNe laser (16 mW, 632.8 nm, spot size 2 mm², energy density of 30 J cm^-2 for rats and 70 J cm^-2 for dogs). This study shows that the low-power laser irradiation prevents extensive glial scar formation (a limiting factor in CNS regeneration) between neural transplants and host brain or spinal cord. Abundant capillaries developed in the laser-irradiated transplants, this being of crucial importance for their survival. The results of the present study and our previous investigations suggest that low-power laser irradiation is a novel tool for treatment of CNS injuries and disorders.