| dc.description.abstract | Dopaminergic neurons located in the Subtancia Nigra pars compacta in the ventral mesencephalon (VM) are essential for the control of voluntary movement, among other function. The pathological hallmark of Parkinson’s disease resides in a severe neurodegeneration of these cells, producing all the classical symptoms of the disease: resting tremor, akinesia, bradikinesia and hipokinesia. Since all the present treatments can not stop the progression of the degenerative process, research was focused on cell replacement therapy. Proof of concept was established when human fetal VM tissue was transplanted into the brain of Parkinson’s disease patients, showing therapeutic effects. Fetal VM cells were able to survive and produce dopaminergic neurons, restoring dopaminergic neurotransmision. But limited tissue availability and ethical problems precluded the implementation of systematic use of this treatment. An alternative source for fetal tissue would be a continuous source of DA neurons from a VM cell line. However, since now, human VM cell lines have not been successfully established due to the poor capacity for efficient culture and production of dopaminergic neurons both in vitro and in vivo.
In our group, we generated a new VM immortalized stem cell line from a 10-week-old human fetus. In the present work, this v-myc immortalized stem cell line (hVM) was characterized and proved to produce large amounts of dopaminergic neurons in addition to glial cells and oligodendrocytes. Thus hVM cell line shows multipotential properties.
When this cell line was analyzed over passages, we found that the generation of neurons and dopaminergic neurons was reduced. Bcl-XL overexpression was then studied in policlonal or clonal hVM cell lines. First, Bcl-XL overexpression efficiently reverted apoptotic cell death during culture differentiation in vitro. Secondly, Bcl-XL induced a marked increase in neuron generation, whilst a profound decrease in the generation of glial cells during the differentiation. Interestingly, Bcl-XL overexpression contributed to increase specifically dopaminergic cells among the neuronal population, as we were able to detect increased expression of dopaminergic transcription factors (Engrailed-1, Nurr1, Pitx3, TH, VMAT-2, Wnt5a) as well as neurogenic factors (Neurogenin2, NeuroD1). These effects seemed to be independent of the anti-apoptotic well-established role of Bcl-XL.
Finally, in vivo studies established that human VM cell lines did survive when trasplanted in a 6-OHDA lesioned rat striatum (hemiparkinsonian animals). Moreover, human VM cells were able to differentiate generating both glial and neuronal cells, and in particular, we could detect the generation of dopaminergic neurons in vivo. In animals grafted with Bcl-XL overexpressing cells, we observed a reduction in their motor asymmetry.
Thus, human VM derived cell lines constitute an interesting tool for generating dopaminergic neuron and understanding the precise molecular role of Bcl-XL in this pathway could lead to optimize dopaminergic neuron differentiation process. | en |
