An increase in neurogenesis could be obtained by two different mechanisms one during proliferation and the other during differentiation partially mimicked by EPO. First, culturing differentiating NPCs under www.selleckchem.com/products/Sorafenib-Tosylate.html lowered oxygen increased the number of neurons after 3 days of differentia tion. In addition, proliferation of NPCs under hypoxia and differentiation of those cells under hypoxic or normoxic conditions raised the same amount of neurons, indicating a manipulation of the progenitor cell pool during prolifera tion. EPO partially mimicked the effect under normoxia and displayed anti apoptotic effects under these culturing conditions. Therefore we propose two different mechanisms of differentiation. One deals with the increase of neuronal cells by hypoxia during differentiation and the other one displays an increase of the progenitor pool of cells during proliferation under hypoxia.

The two mechan isms result in the same effect, namely the increase of neu ronal cells and the increase of the overall activity of differentiated cells. The first mechanism indicates that hypoxia induces differentiation and the second one indi cates that hypoxia increases the pool of differentiating cells by changing the cell fate of the progenitor cells. Prolifera tion was investigated at 3% O2 and the rate of differentia tion did not change when cells were differentiated at 3% as well. These results demonstrate that 3% oxygen modifies the differentiation capability of NPCs. The cell line used in this study showed a maximal number of neurons of around 6%, which can be interpreted as a limitation of this study, however reported levels of neurons in other NPC lines are simi lar.

Nevertheless, this cell line also possesses advantages like the very fast differentiation potential and the easy accessibility, which enabled us to closely monitor changes in proliferation and differentiation. Therefore, those cells serve as a model to investigate differentiation mechanisms which then can be transferred to systems which allow for an engraftment into the CNS to cure neurodegenerative diseases like Parkinsons disease or stroke. Concerning apoptotic cells, the number was reduced by 50% at day 4 of differentiation at 3% oxygen. This apoptotic effect was not in consensus with a neuronal cell death, as the number of neurons was not influenced which leads to the conclusion that the num ber of bIII tub cells at 3 days of differentiation is not only an outcome of an anti apoptotic effect.

At the fourth day of differentiation the effect of EPO is anti apoptotic, but numbers of neuronal cells are not altered by EPO and therefore EPO has no neuron specific anti apoptotic Anacetrapib effect. We observed an increased apoptosis at day 4 in the cells that underwent proliferation and dif ferentiation at 20% oxygen, however the underlying mechanism is not clear. Depending on the severity of hypoxia it can have differential effects on the apoptosis.