Alignment of Carbon Nanotubes: An Approach to Modulate Cell Orientation and Asymmetry

Stem cells offer a promising tool in tissue engineering strategies, as their differentiated derivatives can be used to reconstruct most biological tissues. These approaches rely on controlling the biophysical cues that tune the ultimate fate of cells. In this context, significant effort has gone to parse out the role of conflicting matrix-elicited signals (e.g., topography and elasticity) in regulation of macroscopic characteristics of cells (e.g., shape and polarity). A critical hurdle, however, lies in our inability to recapitulate the nanoscale spatiotemporal pattern of these signals. The study presented in this manuscript took an initial step to overcome this challenge by developing a carbon nanotube (CNT)-based substrate for nanoresolution control of focal adhesion formation and cell alignment. The utility of this system was studied using human umbilical vascular endothelial cells (HUVECs) and human embryonic stem cells (hESCs) at a single cell level. Our results demonstrated the ability to control cell orientation by merely controlling the alignment of focal adhesions at a nanoscale size. Our long-term vision is to use these nanoengineered substrates to mimic cell orientation in earlier development and explore the role of polarity in asymmetric division and lineage specification of dividing cells.

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Evolutionarily Conserved Role of Nucleostemin: Controlling Proliferation of Stem/Progenitor Cells during Early Vertebrate Development

Molecular and Cellular Biology ◽

10.1128/mcb.01183-06 ◽

2006 ◽

Vol 26 (24) ◽

pp. 9291-9301 ◽

Cited By ~ 73

Author(s):

Chantal Beekman ◽

Massimo Nichane ◽

Sarah De Clercq ◽

Marion Maetens ◽

Thomas Floss ◽

...

Keyword(s):

Stem Cells ◽

Cell Proliferation ◽

Embryonic Stem Cells ◽

Progenitor Cells ◽

Control Cell ◽

Embryonic Stem ◽

Physiological Role ◽

Specific Gene

ABSTRACT Nucleostemin (NS) is a putative GTPase expressed preferentially in the nucleoli of neuronal and embryonic stem cells and several cancer cell lines. Transfection and knockdown studies indicated that NS controls the proliferation of these cells by interacting with the p53 tumor suppressor protein and regulating its activity. To assess the physiological role of NS in vivo, we generated a mutant mouse line with a specific gene trap event that inactivates the NS allele. The corresponding NS −/− embryos died around embryonic day 4. Analyses of NS mutant blastocysts indicated that NS is not required to maintain pluripotency, nucleolar integrity, or survival of the embryonic stem cells. However, the homozygous mutant blastocysts failed to enter S phase even in the absence of functional p53. Haploid insufficiency of NS in mouse embryonic fibroblasts leads to decreased cell proliferation. NS also functions in early amphibian development to control cell proliferation of neural progenitor cells. Our results show that NS has a unique ability, derived from an ancestral function, to control the proliferation rate of stem/progenitor cells in vivo independently of p53.

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The role of nucleotide excision repair in protecting embryonic stem cells from genotoxic effects of UV-induced DNA damage

Nucleic Acids Research ◽

10.1093/nar/27.16.3276 ◽

1999 ◽

Vol 27 (16) ◽

pp. 3276-3282 ◽

Cited By ~ 65

Author(s):

P. P. H. Van Sloun ◽

J. G. Jansen ◽

G. Weeda ◽

L. H. F. Mullenders ◽

A. A. van Zeeland ◽

...

Keyword(s):

Stem Cells ◽

Dna Damage ◽

Embryonic Stem Cells ◽

Nucleotide Excision Repair ◽

Excision Repair ◽

Embryonic Stem ◽

Genotoxic Effects ◽

Nucleotide Excision

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Modulation of Differentiation of Embryonic Stem Cells by Polypyrrole: The Impact on Neurogenesis

International Journal of Molecular Sciences ◽

10.3390/ijms22020501 ◽

2021 ◽

Vol 22 (2) ◽

pp. 501

Author(s):

Kateřina Skopalová ◽

Katarzyna Anna Radaszkiewicz ◽

Věra Kašpárková ◽

Jaroslav Stejskal ◽

Patrycja Bober ◽

...

Keyword(s):

Stem Cells ◽

Embryonic Stem Cells ◽

Embryonic Stem ◽

Stem Cell Differentiation ◽

Active Role ◽

Low Molecular Weight ◽

Conducting Materials ◽

The Impact ◽

Erk Kinase

The active role of biomaterials in the regeneration of tissues and their ability to modulate the behavior of stem cells in terms of their differentiation is highly advantageous. Here, polypyrrole, as a representantive of electro-conducting materials, is found to modulate the behavior of embryonic stem cells. Concretely, the aqueous extracts of polypyrrole induce neurogenesis within embryonic bodies formed from embryonic stem cells. This finding ledto an effort to determine the physiological cascade which is responsible for this effect. The polypyrrole modulates signaling pathways of Akt and ERK kinase through their phosphorylation. These effects are related to the presence of low-molecular-weight compounds present in aqueous polypyrrole extracts, determined by mass spectroscopy. The results show that consequences related to the modulation of stem cell differentiation must also be taken into account when polypyrrole is considered as a biomaterial.

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Discovering the role of VEGF signaling pathway in mesendodermal induction of human embryonic stem cells

Biochemical and Biophysical Research Communications ◽

10.1016/j.bbrc.2021.03.036 ◽

2021 ◽

Vol 553 ◽

pp. 58-64

Author(s):

Chenge Xin ◽

Chaonan Zhu ◽

Ying Jin ◽

Hui Li

Keyword(s):

Stem Cells ◽

Embryonic Stem Cells ◽

Signaling Pathway ◽

Human Embryonic Stem Cells ◽

Embryonic Stem ◽

Vegf Signaling ◽

Vegf Signaling Pathway

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Akt signaling is activated by TGFβ2 and impacts tenogenic induction of mesenchymal stem cells

Stem Cell Research & Therapy ◽

10.1186/s13287-021-02167-2 ◽

2021 ◽

Vol 12 (1) ◽

Cited By ~ 1

Author(s):

Sophia K. Theodossiou ◽

Jett B. Murray ◽

LeeAnn A. Hold ◽

Jeff M. Courtright ◽

Anne M. Carper ◽

...

Keyword(s):

Stem Cells ◽

Mesenchymal Stem Cells ◽

Signaling Pathways ◽

Transforming Growth Factor ◽

Akt Signaling ◽

Cell Alignment ◽

Limited Information ◽

Akt Inhibitor ◽

Tenogenic Differentiation

Abstract Background Tissue engineered and regenerative approaches for treating tendon injuries are challenged by the limited information on the cellular signaling pathways driving tenogenic differentiation of stem cells. Members of the transforming growth factor (TGF) β family, particularly TGFβ2, play a role in tenogenesis, which may proceed via Smad-mediated signaling. However, recent evidence suggests some aspects of tenogenesis may be independent of Smad signaling, and other pathways potentially involved in tenogenesis are understudied. Here, we examined the role of Akt/mTORC1/P70S6K signaling in early TGFβ2-induced tenogenesis of mesenchymal stem cells (MSCs) and evaluated TGFβ2-induced tenogenic differentiation when Smad3 is inhibited. Methods Mouse MSCs were treated with TGFβ2 to induce tenogenesis, and Akt or Smad3 signaling was chemically inhibited using the Akt inhibitor, MK-2206, or the Smad3 inhibitor, SIS3. Effects of TGFβ2 alone and in combination with these inhibitors on the activation of Akt signaling and its downstream targets mTOR and P70S6K were quantified using western blot analysis, and cell morphology was assessed using confocal microscopy. Levels of the tendon marker protein, tenomodulin, were also assessed. Results TGFβ2 alone activated Akt signaling during early tenogenic induction. Chemically inhibiting Akt prevented increases in tenomodulin and attenuated tenogenic morphology of the MSCs in response to TGFβ2. Chemically inhibiting Smad3 did not prevent tenogenesis, but appeared to accelerate it. MSCs treated with both TGFβ2 and SIS3 produced significantly higher levels of tenomodulin at 7 days and morphology appeared tenogenic, with localized cell alignment and elongation. Finally, inhibiting Smad3 did not appear to impact Akt signaling, suggesting that Akt may allow TGFβ2-induced tenogenesis to proceed during disruption of Smad3 signaling. Conclusions These findings show that Akt signaling plays a role in TGFβ2-induced tenogenesis and that tenogenesis of MSCs can be initiated by TGFβ2 during disruption of Smad3 signaling. These findings provide new insights into the signaling pathways that regulate tenogenic induction in stem cells.

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