NCS21 Neuronal Supplement is a serum-free supplement for neuronal cell cultures. It is an optimized and modified formulation of B27® Supplement (B27® is a registered trademark of Life Technologies Corporation). NCS21 Neuronal Supplement is suitable for the viable, long-term growth of hippocampal neurons and other neurons of the central nervous system (CNS) and peripheral nervous system (PNS). It is chemically defined and contains vitamins, hormones, and other growth factors, including insulin, human transferrin, catalase, antioxidants, and fatty acids. Suitable applications include, e.g., differentiation of ES cells into neuron lineage (neuron and astrocytes), differentiation of neuronal stem cells into astrocytes and neurons, optimal growth and long-term survival of rat hippocampal neurons (fetal and adult), survival of neurons from embryonic rat striatum, substantia nigra, septum and cortex, and neonatal rat cerebellum (fetal and adult). NCS21 Neuronal Supplement is based upon the open formulation of B27 by Chen et al. (2008), J Neurosci Methods; 171 (2): 239–247, "NS21: re-defined and modified supplement B27 for neuronal cultures".