Biology subjects

Hermanson, O.

Publications and source records attributed to Hermanson, O..

5 recordsLinked to original sources

bioRxiv2019

Pax6 and KDM5C co-occupy a subset of developmentally critical genes including Notch signaling regulators in neural progenitors

Pax6 is a key transcription factor in neural development. While generally viewed as a transcriptional activator, mechanisms underlying Pax6 function as a repressor is less well understood. Here we show that Pax6 acts as a direct repressor of transcription associated with a decrease in H3K4me3 levels. Genome wide analysis of the co-occupancy of the H3K4 demethylase KDM5C and Pax6 with H3K4me3-negative regions revealed 177 peaks on 131 genes. Specific analysis of these Pax6/KDM5C/H3K4me3-peaks unveiled a number of genes associated with Notch signaling, including Dll1, Dll4, and Hes1. RNA knockdown of PAX6/KDM5C in human neural progenitors resulted in increased DLL4 gene expression, decreased DLL1 expression, and no significant effect on HES1 mRNA levels, differences that could be due to gene-specific variations in the chromatin landscape. Our findings suggest that PAX6 and KDM5C co-regulate a subset of genes implicated in brain development, including members of the Notch signaling family.

molecular biology↗

bioRxiv2019

Lithium treatment reverses irradiation-induced changes in rodent neural progenitors

Cranial radiotherapy in children has detrimental effects on cognition, mood, and social competence in young cancer survivors. Treatments harnessing hippocampal neurogenesis are currently of great relevance in this context, and we previously showed that voluntary running introduced long after irradiation rescued hippocampal neurogenesis in young mice (Naylor et al. 2008a). Lithium, a well-known mood stabilizer, has both neuroprotective, pro-neurogenic as well as anti-tumor effects, and in the current study we introduced lithium treatment 4 weeks after irradiation, analogous to the voluntary running study. Female mice received a single 4 Gy whole-brain irradiation dose at postnatal day (PND) 21 and were randomized to 0.24% Li2CO3 chow or normal chow from PND 49 to 77. Hippocampal neurogenesis was assessed at PND 77, 91 and 105. We found that lithium treatment had a pro-proliferative effect on neural progenitors and promoted neuronal integration upon its discontinuation. Gene expression profiling and DNA methylation analysis identified two novel factors related to the observed effects, Tppp, associated with proliferation, and GAD2/65, associated with neuronal signaling. Our results show that lithium treatment reverses irradiation-induced impairment of hippocampal neurogenesis even when introduced long after the injury. We propose that lithium treatment should be intermittent in order to first make neural progenitors proliferate and then, upon discontinuation, allow them to differentiate. Our findings suggest that pharmacological treatment of cognitive so-called late effects in childhood cancer survivors is possible.

neuroscience↗

bioRxiv2019

Live detection of neural stem and glioblastoma cells by an oligothiophene derivative

Here we report a luminescent conjugated oligothiophene (LCO), named p-HTMI, for non-invasive and non-amplified real-time detection of live human patient-derived glioblastoma (GBM) cells and embryonic neural stem cells (NSCs). While p-HTMI stained only a small fraction of other cell types investigated, the mere addition of p-HTMI to the cell culture resulted in efficient detection of NSCs or GBM cells from rodents and humans within minutes. p-HTMI is functionalized with a methylated imidazole moiety resembling the side chain of histidine/histamine, and non-methylated analogues were not functional. p-HTMI were readily able to detect a subpopulation of human cells in vivo in mouse brain sections with tumors developed from orthotopically transplanted patient-derived GBM cells. Cell sorting experiments of human GBM cells demonstrated that p-HTMI labeled the same population as CD271, a proposed marker for stem cell-like cells and rapidly migrating cells in glioblastoma. Our results suggest that the LCO p-HTMI is a versatile tool for immediate and selective detection of subpopulations of neural stem and glioma cells.

bioengineering↗

bioRxiv2019

Optimization of 3D bioprinting of human neuroblastoma cells using sodium alginate hydrogel

There are many parameters in extrusion-based three-dimensional (3D) bioprinting of different materials that require fine-tuning to obtain the optimal print resolution and cell viability. To standardize this process, methods such as parameter optimization index (POI) have been introduced. The POI aims at pinpointing the optimal printing speed and pressure to achieve the highest accuracy keeping theoretical shear stress low. Here we applied the POI to optimize the process of 3D bioprinting human neuroblastoma cell-laden 2% sodium alginate (SA) hydrogel using freeform reversible embedding of suspended hydrogels (FRESH). Our results demonstrate a notable difference between optimal parameters for printing 2% SA with and without cells in the hydrogel. We also detected a significant influence of long-term cell culture on the printed constructs. This observation suggests that the POI has to be evaluated in the perspective of the final application. When taking these conditions into consideration, we could define a set of parameters that resulted in good quality prints maintaining high neuroblastoma cell viability (83% viable cells) during 7 days of cell culture using 2% SA and FRESH bioprinting. These results can be further used to manufacture neuroblastoma in vitro 3D culture systems to be used for cancer research.

bioengineering↗

bioRxiv2019

Recombinant spider silk protein matrices facilitate multi-analysis of calcium-signaling in neural stem cell-derived AMPA-responsive neurons

Neural progenitors or stem cells (NSCs) show great promise in drug discovery and clinical application. Yet few efforts have been made to optimize biocompatible materials for such cells to be expanded and used in clinical conditions. We have previously demonstrated that NSCs are readily cultured on substrates of certain recombinant spider silk protein without addition of animal- or human-derived components. The question remains however whether this material allows differentiation into functional neurons and glia, and whether such differentiation can take place also when the NSCs are cultured within the material in a pseudo-3D context. Here we demonstrate that \"foam\"-like structures generated from recombinant spider silk protein (4RepCT) provided excellent matrices for the generation and multicellular analysis of functional excitatory neurons from NSCs without addition of animal- or human-derived components. NSCs isolated from the cerebral cortices of rat embryos were cultured on either 4RepCT matrices shaped as foam-like structures without coating, or on conventional polystyrene plates coated with poly-L-ornithine and fibronectin. Upon treatment with recombinant proteins including the growth factor BMP4 or a combination of BMP4 and the signaling factor Wnt3a, the cortical NSCs cultured in 4RepCT foam-like structures differentiated efficiently into neurons that responded to glutamate receptor agonists, such as AMPA, to at least the same extent as control cultures. Matrices derived from recombinant spider silk proteins thus provide a functional microenvironment for neural stem cells without any animal- or human-derived components, and can be employed in the development of new strategies in stem cell research and tissue engineering.

bioengineering↗