The mechanism s of this taurine requirement for
The mechanism(s) of this taurine requirement for THZ2 development are poorly understood. The influence of taurine may be exerted on cell division, migration or/and differentiation. These possibilities can be examined in a preparation of neural precursor cells (NPCs) collectively including neural progenitor and stem cells, which are characteristically proliferative and self renewing, and maintain the ability to differentiate into neural cell lineages (Reynolds et al., 1992; Rietze and Reynolds, 2006). NPCs actively proliferate in cultures as floating spherical clusters called neurospheres. This is a widely used technique to characterize a variety of NPCs features. In the proper conditions, i.e. free-serum media supplemented with specific growth factors, NPC cultures can be expanded through several passages. If then switched to serum-containing media, NPCs differentiate into astrocytes, neurons and oligodendrocytes, which are formed in different proportion, being astrocytes the most abundant cell type formed (Ahmed, 2009). A previous study from our laboratory described an effect of taurine increasing proliferation of NPCs generated from embryonic mouse mesencephalon (Hernández-Benítez et al., 2010a) but there is no information about taurine effects in NPCs from the adult brain.
Interest in studies about adult NPCs is raised by the possibility of increasing and manipulating neurogenesis in the adult brain. Neurogenesis persists in some regions of the adult brain derived from NPCs located at the SVZ of the lateral ventricules (Ming and Song, 2011), and it is enhanced by brain injuring conditions such as ischemic stroke, seizures or in neurodegenerative diseases (Arvidsson et al., 2002; Nakatomi et al., 2002; Parent, 2007; Vandenbosch et al., 2011). NPCs may then be a source of neuronal replacement during brain repair. It is therefore of interest to investigate whether taurine has an influence on proliferation or/and differentiation of NPCs obtained from the adult brain. The present study on NPCs obtained from the SVZ of adult mice brain, examined whether taurine affects cell viability and proliferation and evaluated its effect on the proportion of astrocytes and neurons generated after differentiation.
Results Neural precursor cells (NPCs) of the SVZ of mice adult brain, cultured as neurospheres were used in this study. NPCs from adult tissue are currently defined by self-renewal, positive reaction to nestin and multipotent differentiation. We found that i) neurospheres are formed from the dissociated SVZ and expanded through several passages, ii) cells forming neurospheres from passages 1 to 6 ranged 90.4–95.5% positive to nestin, 0.92–2.2% positive to GFAP and 1.2 to 2.3% positive to β-III-tubulin, and iii) under the appropriate conditions, NPCs differentiate into neurons (β-III-tubulin-positive cells) , and astrocytes (GFAP-positive cells) with a marked reduction (up to 2.9%) of nestin-positive cells (Supplementary Figs. 1A–C). It can be then reasonably concluded that our cultures contain essentially NPCs organized as neurospheres. As shown by the range of variation in the quantitative composition of cells, no significant difference was found through the several passages, 1–6. Addition of taurine to cultures markedly increased the number of NPCs. All secondary cultures start with a similar number of cells (about 200×103), which is referred to as the initial cell number. After 96h, taurine cultures contained about 120% more cells than control cultures. This effect of taurine was consistently observed in primary cultures as well as in secondary cultures at all passages (Fig. 1A). The increase with time (1–4days) of NPC number in cultures in the presence or absence of taurine is shown in Fig. 1B. After 24h taurine cultures have significantly more cells (73%) than controls. This difference further increased with time, and at 48, 72 and 96h, taurine cultures have, respectively, 85%, 116% and 120% more cells than controls (Fig. 1B).