Eryrhropoietin increase neuronal differentiation increase neuronal stem cells and death resistant neural stem cells

Neural stem cells transplantation is one of the several methods currently under investigation as a therapy for CNS diseases. Recently, we isolated and characterized a new class of adult neural stem cells from the sub ventricular zone of the mouse brain after a prolonged ischemic stimulus (Marfia et al, 2009). Hypoxic insults determine oxygen deficiency that triggers intrinsic adaptive processes leading to promotion of tissue protection and regeneration (Bunn and Poyton, 1996).These cells named Death Resistant-Neural Stem Cells (DR-NSCs), selected because of a powerful ischemic insult, are the best example of this phenomenon. These cells, isolated from the post mortem murine SVZ are able to proliferate in vitro, showing quantitative and qualitative peculiar features, news compared to classic adult NSCs. Expression of EPO and its receptor (EPO-R) in the nervous system, as well as its multifaceted protective action in cell culture and animal models, have been reported extensively and reviewed in detail elsewhere. Hypoxia-induced expression of EPO and EPO-R in brain cells may contribute to ischemic tolerance [art. 12, 18], whereas neutralization of the brain endogenous EPO augments ischemic damage. In this study we examined the effects of erythropoietin (EPO) on the differentiation of neural progenitor stem cells (T0) and Death Resistant Neural Stem Cells (DR-NSCs) isolated from the adult subventricular zone (SVZ). Our results show that exogenous EPO promotes neuronal differentiation in classical NSC as measured by processes length and branching. Blocking the EPO pathway by monoclonal antibodies directed against EPO or EPOR prevents neuronal differentiation. We tested three different concentrations of EPO 1 U/ml, 10 U/ml, and 50 U/ml and found the optimal concentration of EPO to be 10 U/ml. At 50 U/ml differentiation decreases. Exogenous EPO has also a modest effect on DR-NCS differentiation when administered at low concentrations (1 U/ml and 10 U/ml), but results toxic at concentrations of 50 U/ml. This observation is in contrast with the effect obsrved on classical NSC. As previously shown, DR-NSC but not classical NSCs synthesize EPO (Marfia et al.). In DR-NSCs cultures, exogenous EPO therefore adds up to the endogenously synthesized EPO and may lead to high levels of total EPO, which have been reported to induce a down-regulation of EPO-R and result in the inability to respond to EPO treatment. EPO acts as an autocrine-paracrine signalling molecule for neural stem cell neurognesis and neuronal differentiation, increasing the number of neurons but not astrocytes (Wang et al. 2004, Shingo et al. 2001). Accordingly, we showed that EPO treatment increases the differentiation ability of NSC to the level of DR-NSC and also co-ordinates neural morphology in death resistant neural precursors being one of the main actors in neurogenesis following ischemia