Roles of polysialic acid in migration and differentiation of neural stem cells

Polysialic acid, a homopolymer of alpha2,8-linked sialic acid, is one of the carbohydrates expressed on neural precursors in the embryonic and adult brain. Polysialic acid, synthesized by two polysialyltransferases (ST8SiaII and ST8SiaIV), mainly modulates functions of the neural cell adhesion molecule (NCAM). Polysialic acid-deficient mice demonstrated that polysialylated NCAM plays crucial roles in various steps of neural development, such as cell survival and cell migration of neural precursors, neuronal guidance, and synapse formation. However, the mechanisms of the diverse phenotypes and molecules affected by polysialic acid remain to be defined. To study the roles of polysialic acid on neural stem cells, analyses of neural stem cells from polysialic acid-deficient and NCAM-deficient mice are useful. Here, we describe how to prepare neural precursor cells from mouse brain and how to analyze migration and differentiation of neurosphere cells in vitro.