Neurosphere and neurosphere-forming cells: morphological and ultrastructural characterization.

Despite recent advances in our understanding of neural stem cell (NSC) biology, the free-floating structures generated by these cells in vitro, the "neurospheres", have not been fully characterized. To fill this gap, we examined neurospheres and neurosphere-derived NSCs by confocal microscopy, electron microscopy (EM) and cytofluorimetry. Here, we show that neurospheres and neurosphere-forming cells are morphologically and functionally heterogeneous.

Alternative sources of neurons and glia from somatic stem cells.

Stem cell populations have been shown to be extremely versatile: they can generate differentiated cells specific to the tissue in which they reside and descendents that are of different germ layer origin. This raises the possibility of obtaining neuronal cells from new biological source of the same adult human subjects. In this study, we found that epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) cooperated to induce the proliferation, self-renewal, and expansion of neural stem cell-like population isolated from several newborn and adult mouse tissues: muscle and hematopoietic tissues.

Human neural stem cells express extra-neural markers.

Neural stem cells can be derived from the adult/embryonic nervous system as well as from more primitive embryonic stem cells but, because of the lack of specific markers, only their differentiated progeny can be characterized. We here report the presence of several endothelial and hematopoietic receptors (at protein and mRNA level) on the surface of embryonic human neural stem cells, which are partially maintained during differentiation. This suggests that neural stem cells have a greater potential than previously thought, which involves the ability to respond to different and so far unconsidered environmental signals and may be responsible for the recently discovered process of stem cell-fate conversion.