Unravelling mechanisms of heparan sulfate proteoglycan-mediated control of human neurogenesis

LE Oikari, RK Okolicsanyi, C Yu, LR Griffiths and LM Haupt

Genomics Research Centre, Institute of Health and Biomedical Innovation, School of Biomedical Sciences, Queensland University of Technology

Multipotent neural stem cells (NSCs) have the ability to differentiate towards neurons and glial cells, thus providing a model to study neurogenesis and gliogenesis in vitro as well as having great potential in the regenerative treatment of brain damage. Understanding how human NSC (hNSC) lineage specification is controlled is critical to our improved understanding of human nervous system biology and for the development of stem cell-based therapies for central nervous system injuries. We have recently reported that several cell surface heparan sulfate proteoglycans (HSPGs) are highly expressed in human embryonic stem cell-derived NSCs (hNSC H9) with neuronal and glial specification significantly altering the HSPG profile of these cells (Oikari et al. 2016 Stem Cell Res). With HSPGs likely being important in hNSC differentiation, we are now investigating the role of HSPGs in human neurogenesis. To do this, we have established long-term (day 40 and day 60) hNSC neuronal differentiation cultures under HS (heparin) and key signalling pathway (BDNF and PDGF) modulatory conditions and examined differences cell morphology, viability, neuronal marker expression and functional characteristics in these cultures. The addition of heparin in combination with key growth factors increased cell number and viability and the presence of proliferating cells were higher in the modulated neuronal cultures in comparison to untreated neuronal cultures. In addition, the combination of heparin with BDNF and PDGF had a stimulatory effect on neuronal marker expression when compared to the BDNF or PDGF alone treatment conditions but did not increase culture heterogeneity. These results suggest that modulation of HSPG expression along with key growth factors has the potential to enhance neuronal differentiation efficiency of hNSCs. Our ability to control hNSC lineage fate specification is crucial for downstream use of hNSCs, including the transplantation of these cells to areas of neuronal cell loss caused by neurodegenerative disease or brain trauma.