SciCombinator

Discover the most talked about and latest scientific content & concepts.

Journal: Stem cell research

166

We developed a three-dimensional (3D) cellular microarray platform for the high-throughput (HT) analysis of human neural stem cell (hNSC) growth and differentiation. The growth of an immortalized hNSC line, ReNcell VM, was evaluated on a miniaturized cell culture chip consisting of 60nl spots of cells encapsulated in alginate, and compared to standard 2D well plate culture conditions. Using a live/dead cell viability assay, we demonstrated that the hNSCs are able to expand on-chip, albeit with lower proliferation rates and viabilities than in conventional 2D culture platforms. Using an in-cell, on-chip immunofluorescence assay, which provides quantitative information on cellular levels of proteins involved in neural fate, we demonstrated that ReNcell VM can preserve its multipotent state during on-chip expansion. Moreover, differentiation of the hNSCs into glial progeny was achieved both off- and on-chip six days after growth factor removal, accompanied by a decrease in the neural progenitor markers. The versatility of the platform was further demonstrated by complementing the cell culture chip with a chamber system that allowed us to screen for differential toxicity of small molecules to hNSCs. Using this approach, we showed differential toxicity when evaluating three neurotoxic compounds and one antiproliferative compound, and the null effect of a non-toxic compound at relevant concentrations. Thus, our 3D high-throughput microarray platform may help predict, in vitro, which compounds pose an increased threat to neural development and should therefore be prioritized for further screening and evaluation.

Concepts: DNA, Developmental biology, Stem cell, Bone marrow, Cellular differentiation, Cell culture

156

Aging is associated with increased inflammation and reduced hippocampal neurogenesis, which may in turn contribute to cognitive impairment. Taurine is a free amino acid found in numerous diets, with anti-inflammatory properties. Although abundant in the young brain, the decrease in taurine concentration with age may underlie reduced neurogenesis. Here, we assessed the effect of taurine on hippocampal neurogenesis in middle-aged mice. We found that taurine increased cell proliferation in the dentate gyrus through the activation of quiescent stem cells, resulting in increased number of stem cells and intermediate neural progenitors. Taurine had a direct effect on stem/progenitor cells proliferation, as observed in vitro, and also reduced activated microglia. Furthermore, taurine increased the survival of newborn neurons, resulting in a net increase in adult neurogenesis. Together, these results show that taurine increases several steps of adult neurogenesis and support a beneficial role of taurine on hippocampal neurogenesis in the context of brain aging.

Concepts: Central nervous system, Neuron, Brain, Amino acid, Stem cell, Hippocampus, Dentate gyrus, Neurogenesis

155

Somatic cells can be reprogrammed into induced pluripotent stem cells (iPSC) by the forced expression of the transcription factors OCT4, SOX2, KLF4 and c-MYC. Pluripotent reprogramming appears as a slow and inefficient process because of genetic and epigenetic barriers of somatic cells. In this report, we have extended previous observations concerning donor age and passage number of human fibroblasts as critical determinants of the efficiency of iPSC induction. Human fibroblasts from 11 different donors of variable age were reprogrammed by ectopic expression of reprogramming factors. Although all fibroblasts gave rise to iPSC colonies, the reprogramming efficiency correlated negatively and declined rapidly with increasing donor age. In addition, the late passage fibroblasts gave less reprogrammed colonies than the early passage cell counterparts, a finding associated with the cellular senescence-induced upregulation of p21. Knockdown of p21 restored iPSC generation even in long-term passaged fibroblasts of an old donor, highlighting the central role of the p53/p21 pathway in cellular senescence induced by both donor age and culture time.

Concepts: DNA, Genetics, Gene expression, Organism, Developmental biology, Stem cell, Stem cells, Induced pluripotent stem cell

150

Amyotrophic Lateral Sclerosis (ALS) is a severe and fatal neurodegenerative disease characterized by progressive loss of motoneurons, muscle atrophy and paralysis. Recent evidence suggests that ALS should be considered as a multi-systemic disease, in which several cell types contribute to motoneuron degeneration. In this view, mutations in ALS linked genes in other neural and non-neural cell types may exert non-cell autonomous effects on motoneuron survival and function. Induced Pluripotent Stem Cells (iPSCs) have been recently derived from several patients with ALS mutations and it has been shown that they can generate motoneurons in vitro, providing a valuable tool to study ALS. However, the potential of iPSCs could be further valorized by generating other cell types that may be relevant to the pathology. In this paper, by taking advantage of a novel inducible system for MyoD expression, we show that both control iPSCs and iPSCs carrying mutations in ALS genes can generate skeletal muscle cells. We provide evidence that both control and mutant iPSC-derived myotubes are functionally active. This in vitro system will be instrumental to dissect the molecular and cellular pathways impairing the complex motoneuron microenvironment in ALS.

Concepts: DNA, Gene, Cell, Developmental biology, Stem cell, Muscle, Amyotrophic lateral sclerosis, Atrophy

149

Human umbilical cord (hUC) blood and tissue are non-invasive sources of potential stem/progenitor cells with similar cell surface properties as bone marrow stromal cells (BMSCs). While they are limited in cord blood, they may be more abundant in hUC. However, the hUC is an anatomically complex organ and the potential of cells in various sites of the hUC has not been fully explored. We dissected the hUC into its discrete sites and isolated hUC cells from the cord placenta junction (CPJ), cord tissue (CT), and Wharton’s jelly (WJ). Isolated cells displayed fibroblastoid morphology, and expressed CD29, CD44, CD73, CD90, and CD105, and showed evidence of differentiation into multiple lineages in vitro. They also expressed low levels of pluripotency genes, OCT4, NANOG, SOX2 and KLF4. Passaging markedly affected cell proliferation with concomitant decreases in the expression of pluripotency and other markers, and an increase in chondrogenic markers. Microarray analysis further revealed the differences in the gene expression of CPJ-, CT- and WJ-hUC cells. Five coding and five lncRNA genes were differentially expressed in low vs. high passage hUC cells. Only MAEL was expressed at high levels in both low and high passage CPJ-hUC cells. They displayed a greater proliferation limit and a higher degree of multi-lineage differentiation in vitro and warrant further investigation to determine their full differentiation capacity, and therapeutic and regenerative medicine potential.

Concepts: DNA, Gene, Gene expression, Bacteria, Developmental biology, Stem cell, Bone marrow, Umbilical cord

148

Epigenetic changes, such as alteration of DNA methylation patterns, have been proposed as a molecular mechanism underlying the effect of alcohol on the maintenance of adult stem cells. We have performed genome-wide gene expression microarray and DNA methylome analysis to identify molecular alterations via DNA methylation changes associated with exposure of human dental pulp stem cells (DPSCs) to ethanol (EtOH). By combined analysis of the gene expression and DNA methylation, we have found a significant number of genes that are potentially regulated by EtOH-induced DNA methylation. As a focused approach, we have also performed a pathway-focused RT-PCR array analysis to examine potential molecular effects of EtOH on genes involved in epigenetic chromatin modification enzymes, fibroblastic markers, and stress and toxicity pathways in DPSCs. We have identified and verified that lysine specific demethylase 6B (KDM6B) was significantly dysregulated in DPSCs upon EtOH exposure. EtOH treatment during odontogenic/osteogenic differentiation of DPSCs suppressed the induction of KDM6B with alterations in the expression of differentiation markers. Knockdown of KDM6B resulted in a marked decrease in mineralization from implanted DPSCs in vivo. Furthermore, an ectopic expression of KDM6B in EtOH-treated DPSCs restored the expression of differentiation-related genes. Our study has demonstrated that EtOH-induced inhibition of KDM6B plays a role in the dysregulation of odontogenic/osteogenic differentiation in the DPSC model. This suggests a potential molecular mechanism for cellular insults of heavy alcohol consumption that can lead to decreased mineral deposition potentially associated with abnormalities in dental development and also osteopenia/osteoporosis, hallmark features of fetal alcohol spectrum disorders.

Concepts: DNA, Gene, Gene expression, Histone, Epigenetics, Organism, Cellular differentiation, DNA methylation

147

Generating human podocytes in vitro could offer a unique opportunity to study human diseases. Here, we describe a simple and efficient protocol for obtaining functional podocytes in vitro from human induced pluripotent stem cells. Cells were exposed to a three-step protocol, which induced their differentiation into intermediate mesoderm, then into nephron progenitors and, finally, into mature podocytes. After differentiation, cells expressed the main podocyte markers, such as synaptopodin, WT1, α-Actinin-4, P-cadherin and nephrin at the protein and mRNA level, and showed the low proliferation rate typical of mature podocytes. Exposure to Angiotensin II significantly decreased the expression of podocyte genes and cells underwent cytoskeleton rearrangement. Cells were able to internalize albumin and self-assembled into chimeric 3D structures in combination with dissociated embryonic mouse kidney cells. Overall, these findings demonstrate the establishment of a robust protocol that, mimicking developmental stages, makes it possible to derive functional podocytes in vitro.

Concepts: DNA, Protein, Gene expression, Developmental biology, Stem cell, Embryonic stem cell, Induced pluripotent stem cell, Podocyte

146

Human lymphoblast cells from a female and male patient diagnosed with Alzheimer’s disease (AD) with different genotypes of a functional copy number variation (CNV) in the AD risk gene CR1 were used to generate integration-free induced pluripotent stem cells (iPSCs) employing episomal plasmids expressing OCT4, SOX2, NANOG, LIN28, c-MYC and L-MYC. The iPSCs retained the CR1 CNV, and comparative transcriptome analyses with the human embryonic stem cell line H1 revealed a Pearson correlation of 0.956 for AD1-CR10 and 0.908 for AD1-CR14.

Concepts: DNA, Gene, Cell, Copy number variation, Stem cell, Stem cells, Embryonic stem cell, Induced pluripotent stem cell

146

Frontotemporal dementia with parkinsonism linked to chromosome 17q21.2 (FTDP-17) is an autosomal-dominant neurodegenerative disorder. Mutations in the gene coding the microtubule-associated protein tau (MAPT) can cause FTDP-17 but the underlying mechanisms of the disease are still unknown. Induced pluripotent stem cells (iPSCs) hold great promise to model FTDP-17 as such cells can be differentiated in vitro to the required neuronal cell type. Here, we report the generation of iPSCs from a 44-year-old symptomatic woman carrying a S305I mutation in the MAPT-gene.

Concepts: DNA, Gene, Cell, Developmental biology, Stem cell, Cell biology, Induced pluripotent stem cell, Progressive supranuclear palsy

146

Adipose tissue expansion during periods of excess nutrient intake requires significant turnover of the extracellular matrix (ECM) to allow for maximal lipid filling. Recent data suggest that stromal cells may be a primary contributor to ECM modifications in visceral adipose. The purpose of this study was to investigate the capacity for high fat diet (HFD)-induced obesity to alter adipose-derived stromal cell (ADSC) relative quantity and ECM gene expression, and determine the extent to which exercise training can mitigate such changes. Male C57BL/6J mice were placed on control or HFD for 8weeks prior to and following initiation of a 16week treadmill exercise program. ADSCs (Sca-1(+)CD45(-)) were isolated from epididymal adipose tissue and mRNA was evaluated using high throughput qPCR. Stromal cells were also obtained from skeletal muscle (MDSC). HFD decreased the quantity of ADSCs and markedly altered gene expression related to ECM remodeling (Col1α1, MMP2, MMP9, Timp1). Exercise did not reverse these changes. MDSCs were minimally altered by HFD or exercise. Overall, the data from this study suggest that ADSCs decrease in quantity and contribute to adipose ECM remodeling in response to obesity, and exercise training does not significantly impact these outcomes.

Concepts: DNA, Gene, Genetics, Cell nucleus, Gene expression, Organism, Obesity, Adipose tissue