Microenvironmental control and molecular detection of neural stem cell state and fate

Sammanfattning: Neural stem cell growth and specialization is dependent on microenvironmental cues, such as growth factors, oxygen levels and substrate stiffness. Together these cues define the genetic and epigenetic program of neural stem cells. In our studies we have manipulated these cues in order to achieve better control of neural stem cell state and fate. In addition, we introduce a novel way of detecting neural stem cells and cancer stem cells in culture. Luminescent conjugated oligothiophenes (LCO) are short polymers, which cross the cell membrane and generate luminescence in the range of wavelengths of ordinary fluorescent probes. In paper I we present a novel LCO, p- HTMI, for detection of live neural stem cells but not differentiated cells. p-HTMI represents a new generation of molecular probes for immediate and non-invasive live detection of specific cell types. In paper II we show that the NADH-sensitive transcriptional co-repressor, CtBP, controls a switch between neuronal and nonneuronal cell fates in oxygen and BMP rich environments. CtBP molecularly integrates microenvironmental levels of BMP and oxygen through Notch mediated regulation of anti- and pro-neural genes. Furthermore, we manipulated growth factor presentation in the stem cell microenvironment through inkjet printing technology. In paper III, we show that inkjet printed macromolecules remained biologically active when printed on hydrogels and control the differentiation of neural stem cells. Finally, in paper IV we demonstrate that soft substrates with brain-like stiffness promote the maturation of neurons. This defines substrate stiffness as a crucial parameter in neuronal differentiation of neural stem cells.