A factor from the injured lower vertebrate CNS promotes outgrowth from human fetal brain neurons

Unlike mammals, lower vertebrates retain the capacity to regenerate damaged central nervous system (CNS) pathways throughout life. In previous studies, we have used the goldfish optic nerve (ON) as a model for CNS regeneration, and found that the injured goldfish ON selectively secretes a factor that promotes process outgrowth of cultured neurons, including neurons of the developing rodent CNS. In the current study, we found that a factor similarly obtained from the injured goldfish ON also has potent outgrowth-promoting effects on cerebrocortical neurons of the fetal human brain, and that these effects are dependent on the age of fetal neurons. This factor appeared to be a protein of mol. wt. greater than 12,000, and was associated with a distinctive morphology of neurite outgrowth. The neurite-promoting factor from the injured goldfish ON may be homologous to factors within the developing human brain.