FIGURE 7.

Neural lineage specification. (A) Established progression of maturing cells during neural lineage specification from pluripotent embryonic stem cells through to specified, mature neural cell types. As cells mature they retain some self-renewal ability (green arrows) while becoming more lineage restricted, until the final stages of specification when cells differentiate to produce a predetermined mature cell type with specific functions. (B) Summary of gene expression changes seen in human mesenchymal stem cell (hMSC) induced neurospheres (hMSC IN), relative to undifferentiated hMSCs. Note the similarities in gene expression changes (heparan sulfate proteoglycan; HSPG and neural) between the hMSC IN and human neural stem cells (hNSC H9). In addition, the summary highlights the down regulation of mesenchymal specific markers used to identify the traditional mesodermal lineage potential of hMSCs. This data provides supporting evidence that generation of hMSC IN cultures results in a more lineage restricted cell type than a true neural stem cell, but that this common progenitor-like cell retains multi-lineage capacity, with increased neural potential. (Mature cell type images from: Ivins et al., 1997; Johnson et al., 2007).