Faculty Opinions recommendation of Genetic Variability Overrides the Impact of Parental Cell Type and Determines iPSC Differentiation Potential.

AbstractThe need for an autologous cell source for bone tissue engineering and medical applications has led researchers to explore multipotent mesenchymal stromal cells (MSC), which show stem cell plasticity, in various human tissues. However, MSC with different tissue origins vary in their biological properties and their capability for osteogenic differentiation. Furthermore, MSC-based therapies require large-scale ex vivo expansion, accompanied by cell type-specific replicative senescence, which affects osteogenic differentiation. To elucidate cell type-specific differences in the osteogenic differentiation potential and replicative senescence, we analysed the impact of BMP and TGF-β signaling in adipose-derived stromal cells (ASC), fibroblasts (FB), and dental pulp stromal cells (DSC). We used inhibitors of BMP and TGF-β signaling, such as SB431542, dorsomorphin and/or a supplemental addition of BMP-2. The expression of high-affinity binding receptors for BMP-2 and calcium deposition with alizarin red S were evaluated to assess osteogenic differentiation potential. Our study demonstrated that TGF-β signaling inhibits osteogenic differentiation of ASC, DSC and FB in the early cell culture passages. Moreover, DSC had the best osteogenic differentiation potential and an activation of BMP signaling with BMP-2 could further enhance this capacity. This phenomenon is likely due to an increased expression of activin receptor-like kinase-3 and -6. However, in DSC with replicative senescence (in cell culture passage 10), osteogenic differentiation sharply decreased, and the simultaneous use of BMP-2 and SB431542 did not result in further improvement of this process. In comparison, ASC retain a similar osteogenic differentiation potential regardless of whether they were in the early (cell culture passage 3) or later (cell culture passage 10) stages. Our study elucidated that ASC, DSC, and FB vary functionally in their osteogenic differentiation, depending on their tissue origin and replicative senescence. Therefore, our study provides important insights for cell-based therapies to optimize prospective bone tissue engineering strategies.

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The impact of statins on biological characteristics of stem cells provides a novel explanation for their pleiotropic beneficial and adverse clinical effects

AJP Cell Physiology ◽

10.1152/ajpcell.00406.2014 ◽

2015 ◽

Vol 309 (8) ◽

pp. C522-C531 ◽

Cited By ~ 23

Author(s):

Reza Izadpanah ◽

Deborah J. Schächtele ◽

Andreas B. Pfnür ◽

Dong Lin ◽

Douglas P. Slakey ◽

...

Keyword(s):

Stem Cells ◽

Cardiovascular Mortality ◽

Memory Loss ◽

Clinical Effects ◽

Differentiation Potential ◽

Plaque Instability ◽

Fibrous Cap ◽

Macrophage Density ◽

Increased Risk ◽

The Impact

Statins reduce atherosclerotic events and cardiovascular mortality. Their side effects include memory loss, myopathy, cataract formation, and increased risk of diabetes. As cardiovascular mortality relates to plaque instability, which depends on the integrity of the fibrous cap, we hypothesize that the inhibition of the potential of mesenchymal stem cells (MSCs) to differentiate into macrophages would help to explain the long known, but less understood “non-lipid-associated” or pleiotropic benefit of statins on cardiovascular mortality. In the present investigation, MSCs were treated with atorvastatin or pravastatin at clinically relevant concentrations and their proliferation, differentiation potential, and gene expression profile were assessed. Both types of statins reduced the overall growth rate of MSCs. Especially, statins reduced the potential of MSCs to differentiate into macrophages while they exhibited no direct effect on macrophage function. These findings suggest that the limited capacity of MSCs to differentiate into macrophages could possibly result in decreased macrophage density within the arterial plaque, reduced inflammation, and subsequently enhance plaque stability. This would explain the non-lipid-associated reduction in cardiovascular events. On a negative side, statins impaired the osteogenic and chondrogenic differentiation potential of MSCs and increased cell senescence and apoptosis, as indicated by upregulation of p16, p53 and Caspase 3, 8, and 9. Statins also impaired the expression of DNA repair genes, including XRCC4, XRCC6, and Apex1. While the effect on macrophage differentiation explains the beneficial side of statins, their impact on other biologic properties of stem cells provides a novel explanation for their adverse clinical effects.

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Effect of Substrate Elasticity on In Vitro Aging of Human Mesenchymal Stem Cells

MRS Proceedings ◽

10.1557/opl.2012.1678 ◽

2012 ◽

Vol 1498 ◽

pp. 39-45

Author(s):

Courtney E. LeBlon ◽

Caitlin R. Fodor ◽

Tony Zhang ◽

Xiaohui Zhang ◽

Sabrina S. Jedlicka

Keyword(s):

Stem Cells ◽

Mesenchymal Stem Cells ◽

Elastic Modulus ◽

Myogenic Differentiation ◽

Human Mesenchymal Stem Cells ◽

Immunofluorescent Staining ◽

Differentiation Potential ◽

Gene And Protein Expression ◽

The Impact

ABSTRACTHuman mesenchymal stem cells (hMSCs) were routinely cultured on tissue-culture polystyrene (TCPS) to investigate the in vitro aging and cell stiffening. hMSCs were also cultured on thermoplastic polyurethane (TPU), which is a biocompatible polymer with an elastic modulus of approximately 12.9MPa, to investigate the impact of substrate elastic modulus on cell stiffening and differentiation potential. Cells were passaged over several generations on each material. At each passage, cells were subjected to osteogenic and myogenic differentiation. Local cell elastic modulus was measured at every passage using atomic force microscopy (AFM) indentation. Gene and protein expression was examined using qRT-PCR and immunofluorescent staining, respectively, for osteogenic and myogenic markers. Results show that the success of myogenic differentiation is highly reliant on the elastic modulus of the undifferentiated cells. The success of osteogenic differentiations is most likely somewhat dependent on the cell elastic modulus, as differentiations were more successful in earlier passages, when cells were softer.

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Evolutionary origin of the cell nucleus and its functional architecture

Essays in Biochemistry ◽

10.1042/bse0480001 ◽

2010 ◽

Vol 48 ◽

pp. 1-24 ◽

Cited By ~ 15

Author(s):

Jan Postberg ◽

Hans J. Lipps ◽

Thomas Cremer

Keyword(s):

Cell Nucleus ◽

Interdisciplinary Research ◽

Nuclear Organization ◽

Nuclear Architecture ◽

Evolutionary Origin ◽

Cell Type ◽

Research Strategies ◽

Evolutionarily Conserved ◽

Species Specific ◽

The Impact

Understanding the evolutionary origin of the nucleus and its compartmentalized architecture provides a huge but, as expected, greatly rewarding challenge in the post-genomic era. We start this chapter with a survey of current hypotheses on the evolutionary origin of the cell nucleus. Thereafter, we provide an overview of evolutionarily conserved features of chromatin organization and arrangements, as well as topographical aspects of DNA replication and transcription, followed by a brief introduction of current models of nuclear architecture. In addition to features which may possibly apply to all eukaryotes, the evolutionary plasticity of higher-order nuclear organization is reflected by cell-type- and species-specific features, by the ability of nuclear architecture to adapt to specific environmental demands, as well as by the impact of aberrant nuclear organization on senescence and human disease. We conclude this chapter with a reflection on the necessity of interdisciplinary research strategies to map epigenomes in space and time.

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Genetic variability in COVID-19-related genes in the Brazilian population

10.1101/2020.12.04.411736 ◽

2020 ◽

Author(s):

Rodrigo Secolin ◽

Tânia K. de Araujo ◽

Marina C. Gonsales ◽

Cristiane S. Rocha ◽

Michel Naslavsky ◽

...

Keyword(s):

Genetic Variability ◽

Rare Variants ◽

Brazilian Population ◽

Type I ◽

Phase 3 ◽

Clinical Prognosis ◽

Hla Alleles ◽

Link Type ◽

Human Lung Cells ◽

The Impact

ABSTRACTSARS-CoV-2 employs the angiotensin-converting enzyme 2 (ACE2) receptor and the transmembrane serine protease (TMPRSS2) to infect human lung cells. Previous studies have suggested that different host genetic backgrounds in ACE2 and TMPRSS2 could contribute to differences in the rate of infection or severity of COVID-19. Recent studies also showed that variants in 15 genes related to type I interferon immunity to influenza virus could predispose to life-threatening COVID-19 pneumonia. Additional genes (SLC6A20, LZTFL1, CCR9, FYCO1, CXCR6, XCR1, IL6, CTSL, ABO, and FURIN) and HLA alleles have also been implicated in response to infection with SARS-CoV-2. Currently, Brazil has recorded the third-highest number of COVID-19 patients worldwide. We aim to investigate the genetic variation present in COVID-19-related genes in the Brazilian population. We analysed 27 candidate genes and HLA alleles in 954 admixed Brazilian exomes. We used the information available in two public databases (http://www.bipmed.org and http://abraom.ib.usp.br/), and additional exomes from individuals born in southeast Brazil, the region with the highest number of COVID-19 patients in the country. Variant allele frequencies were compared with the 1000 Genomes Project phase 3 (1KGP) and the gnomAD databases. We found 395 non-synonymous variants; of these, 325 were also found in the 1000 Genome Project phase 3 (1KGP) and/or gnomAD. Six of these variants were previously reported as putatively influencing the rate of infection or clinical prognosis for COVID-19. The remaining 70 variants were identified exclusively in the Brazilian sample, with a mean allele frequency of 0.0025. In silico prediction of the impact in protein function revealed that three of these rare variants were pathogenic. Furthermore, we identified HLA alleles that were previously associated with COVID-19 response at loci DQB1 and DRB1. Our results showed genetic variability common to other populations, but also rare and ultra-rare variants exclusively found in the Brazilian population. These findings could potentially lead to differences in the rate of infection or response to infection by SARS-CoV-2 and should be further investigated in patients with the disease.

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Differences in DNA methylation of white blood cell types at birth and in adulthood reflect postnatal immune maturation and influence accuracy of cell type prediction

10.1101/399279 ◽

2018 ◽

Cited By ~ 3

Author(s):

Meaghan J Jones ◽

Louie Dinh ◽

Hamid Reza Razzaghian ◽

Olivia de Goede ◽

Julia L MacIsaac ◽

...

Keyword(s):

Dna Methylation ◽

Immune System ◽

Blood Cell ◽

Cord Blood ◽

White Blood Cell ◽

Blood Cells ◽

Cell Types ◽

Cell Type ◽

Cell Type Specific ◽

The Impact

AbstractBackgroundDNA methylation profiling of peripheral blood leukocytes has many research applications, and characterizing the changes in DNA methylation of specific white blood cell types between newborn and adult could add insight into the maturation of the immune system. As a consequence of developmental changes, DNA methylation profiles derived from adult white blood cells are poor references for prediction of cord blood cell types from DNA methylation data. We thus examined cell-type specific differences in DNA methylation in leukocyte subsets between cord and adult blood, and assessed the impact of these differences on prediction of cell types in cord blood.ResultsThough all cell types showed differences between cord and adult blood, some specific patterns stood out that reflected how the immune system changes after birth. In cord blood, lymphoid cells showed less variability than in adult, potentially demonstrating their naïve status. In fact, cord CD4 and CD8 T cells were so similar that genetic effects on DNA methylation were greater than cell type effects in our analysis, and CD8 T cell frequencies remained difficult to predict, even after optimizing the library used for cord blood composition estimation. Myeloid cells showed fewer changes between cord and adult and also less variability, with monocytes showing the fewest sites of DNA methylation change between cord and adult. Finally, including nucleated red blood cells in the reference library was necessary for accurate cell type predictions in cord blood.ConclusionChanges in DNA methylation with age were highly cell type specific, and those differences paralleled what is known about the maturation of the postnatal immune system.

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Proliferation and differentiation potential of rat forebrain oligodendroglial progenitors both in vitro and in vivo

Development ◽

10.1242/dev.111.4.1061 ◽

1991 ◽

Vol 111 (4) ◽

pp. 1061-1080 ◽

Cited By ~ 7

Author(s):

R. Hardy ◽

R. Reynolds

Keyword(s):

Progenitor Cell ◽

Neonatal Rat ◽

Myelin Proteins ◽

Brdu Incorporation ◽

Cell Type ◽

Differentiation Potential ◽

Serum Free ◽

Rat Forebrain

We have followed the development of the O-2A progenitor cell from the neonatal rat forebrain, both in dissociated cell culture and in cryostat sections, using immunocytochemical techniques employing a panel of antibodies that recognise the cells at different stages of their development. This included the monoclonal antibody LB1, which binds to the surface ganglioside GD3 expressed on O-2A progenitor cells. In secondary cultures enriched for O-2A progenitors maintained in a serum-free chemically defined medium, a large proportion of the cells are primed to differentiate into oligodendroglia and go on to express the oligodendroglial specific surface glycolipid galactocerebroside (GC) and then the myelin proteins CNP and MBP. However, a significant proportion of immature bipolar GD3+ cells remained after 6 days in secondary culture. It appears that not all the O-2A progenitors in our cultures differentiate immediately and some cells remain in an undifferentiated state and divide to replenish progenitor numbers. We have also identified in our cultures a small apolar GD3- cell, which when isolated differentiated into a GD3+ bipolar O-2A progenitor cell. We have termed this cell type a preprogenitor. The differentiation of this cell type into O-2A progenitors may be the source of the immature GD3+ cells present at the later stages of our secondary cultures. The proliferative profile of the cultures was studied using 5′bromo-2-deoxyuridine (BrdU) incorporation as an index of mitosis. Only the immature, bipolar O-2A progenitors were seen to divide at any time in serum-free culture. Neither the more mature multipolar O-2A cells nor the oligodendroglia were seen to divide. The developmental profile of the O-2A cells in the rat forebrain in vivo showed a largely similar progression to that in culture, with a time lag of at least 6 days between GD3 expression and the onset of myelination. BrdU incorporation studies in vivo also showed that the GD3+ progenitor cell is mitotic whereas the GC(+)-expressing oligodendroglia is not. We have shown that there are several significant alterations in the timing of antigen expression in both O-2A progenitors and oligodendroglia in vitro compared to that seen in vivo.

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The Impact of Apolipoprotein E Genetic Variability in Health and Life Span

The Journals of Gerontology Series A ◽

10.1093/gerona/glaa175 ◽

2020 ◽

Vol 75 (10) ◽

pp. 1855-1857

Author(s):

Nalini Raghavachari

Keyword(s):

Genetic Variability ◽

Apolipoprotein E ◽

Life Span ◽

The Impact

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Neuronal Circuits in Barrel Cortex for Whisker Sensory Perception

Physiological Reviews ◽

10.1152/physrev.00019.2019 ◽

2021 ◽

Vol 101 (1) ◽

pp. 353-415

Author(s):

Jochen F. Staiger ◽

Carl C. H. Petersen

Keyword(s):

Barrel Cortex ◽

Specific Activity ◽

Sensory Information ◽

Inhibitory Neurons ◽

Future Research ◽

Cell Type ◽

Molecular Features ◽

Somatotopic Map ◽

Cell Type Specific ◽

The Impact

The array of whiskers on the snout provides rodents with tactile sensory information relating to the size, shape and texture of objects in their immediate environment. Rodents can use their whiskers to detect stimuli, distinguish textures, locate objects and navigate. Important aspects of whisker sensation are thought to result from neuronal computations in the whisker somatosensory cortex (wS1). Each whisker is individually represented in the somatotopic map of wS1 by an anatomical unit named a ‘barrel’ (hence also called barrel cortex). This allows precise investigation of sensory processing in the context of a well-defined map. Here, we first review the signaling pathways from the whiskers to wS1, and then discuss current understanding of the various types of excitatory and inhibitory neurons present within wS1. Different classes of cells can be defined according to anatomical, electrophysiological and molecular features. The synaptic connectivity of neurons within local wS1 microcircuits, as well as their long-range interactions and the impact of neuromodulators, are beginning to be understood. Recent technological progress has allowed cell-type-specific connectivity to be related to cell-type-specific activity during whisker-related behaviors. An important goal for future research is to obtain a causal and mechanistic understanding of how selected aspects of tactile sensory information are processed by specific types of neurons in the synaptically connected neuronal networks of wS1 and signaled to downstream brain areas, thus contributing to sensory-guided decision-making.

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