Καλλιέργεια νευρικών βλαστικών κυττάρων και διαφοροποίησή τους προς τη νευρωνική κατεύθυνση

Abstract

The adult nervous system has limited ability to regenerate lost neural tissue after brain damage, or neurodegenerative disease. For this reason efforts are being made for the development of novel therapeutic strategies. Transplantation of suitable cell types including neural stem/progenitor cells (NPCs) into the adult central nervous system (CNS) has attracted considerable interest as a potential approach to overcome the regenerative limitations of the lesioned brain or spinal cord and replace lost or damaged cells. NPCs have been isolated from embryonic, postnatal or adult brain tissue of different species. It is well- established that these cells constitute a heterogenous population of mitotically active, self-renewing progenitor or immature precursor cells that can be expanded in vitro and under specific conditions give rise to neurons, astrocytes and oligodendrocytes. This dynamic cell population has been extensively used as a cellular transplantation source. Additionaly, their lower proliferation potential as compared to embryonic stem cells renders them a safer solution for cell transplantation as the risk for tumorigenesis is minimized. However, the yield of NPC-derived neurons is generally low, thus hampering their potential for neuronal replacement. The goal of the present thesis was to increase the potential of NPCs to generate neurons and to investigate the therapeutic potential of these cells after transplantation in an adult mouse model of traumatic brain injury. For this purpose we used NPCs derived from the cortical brain area of mouse embryos at E14.5 (embryonic day 14.5) with or without genetic modification to overexpress the neuronal differentiation-promoting protein Cend1/BM88. Cend1 is a neuronal protein widely expressed in the central and peripheral nervous systems of mammals and particularly in mature differentiated neurons of the adult. Previous studies have shown that is also expressed, albeit at lower levels, in the proliferating progenitor cells present in the two neurogenic areas of the adult brain namely the subventricular zone and the hippocampus. Previous studies in the early chick spinal cord have shown that overexpression of Cend1 protein can drive progenitor cells out of the cell cycle leading them to differentiate predominantly into neurons. To explore the involvement of Cend1 in the differentiation process of mammalian progenitor cells we isolated in the present study, NPCs from the mouse embryonic spinal cord. By using gene transfer technology we achieved overexpression or silencing of Cend1 protein in spinal cord NPCs and analysed their proliferation and differentiation properties in vitro under these two different conditions. Our results support that Cend1 participates in the differentiation programme of spinal cord NPCs towards a neuronal phenotype. ................