| 31. |
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| 32. |
- Ellerström, Catharina, et al.
(författare)
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Facilitated expansion of human embryonic stem cells by single-cell enzymatic dissociation
- 2007
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Ingår i: Stem Cells. - : Oxford University Press (OUP). - 1549-4918 .- 1066-5099. ; 25:7, s. 1690-1696
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Tidskriftsartikel (refereegranskat)abstract
- Traditionally, human embryonic stem cells (hESCs) are propagated by mechanical dissection or enzymatic dissociation into clusters of cells. To facilitate up-scaling and the use of hESC in various experimental manipulations, such as fluorescence-activated cell sorting, electroporation, and clonal selection, it is important to develop new, stable culture systems based on single-cell enzymatic propagation. Here, we show that hESCs, which were derived and passaged by mechanical dissection, can be rapidly adjusted to propagation by enzymatic dissociation to single cells. As an indication of the stability of this culture system, we demonstrate that hESCs can be maintained in an undifferentiated, pluripotent, and genetically normal state for up to 40 enzymatic passages. We also demonstrate that a recombinant trypsin preparation increases clonal survival compared with porcine trypsin. Finally, we show that human foreskin fibroblast feeders are superior to the commonly used mouse embryonic fibroblast feeders in terms of their ability to prevent spontaneous differentiation after single-cell passaging. Importantly, the culture system is widely applicable and should therefore be of general use to facilitate reliable large-scale cultivation of hESCs, as well as their use in various experimental manipulations.
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| 33. |
- Fritze, Jonas, et al.
(författare)
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Loss of Cxcr5 alters neuroblast proliferation and migration in the aged brain
- 2020
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Ingår i: Stem Cells. - : Oxford University Press (OUP). - 1066-5099 .- 1549-4918. ; 38:9, s. 1175-1187
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Tidskriftsartikel (refereegranskat)abstract
- Neurogenesis, the production of new neurons from neural stem cells, dramatically decreases during aging concomitantly with increased inflammation both systemically and in the brain. However, the precise role of inflammation and whether local or systemic factors drive the neurogenic decline during aging is poorly understood. Here, we identify CXCR5/5/CXCL13 signaling as a novel regulator of neurogenesis in the aged brain. The chemokine Cxcl13 was found to be upregulated in the brain during aging. Loss of its receptor, Cxcr5, led to increased proliferation and decreased numbers of neuroblasts in the aged subventricular zone (SVZ), together with accumulation of neuroblasts in the rostral migratory stream and olfactory bulb (OB), without increasing the amount of new mature neurons in the OB. The effect on proliferation and migration was specific to neuroblasts and likely mediated through increased levels of systemic IL-6 and local Cxcl12 expression in the SVZ. Our study raises the possibility of a new mechanism by which interplay between systemic and local alterations in inflammation regulates neurogenesis during aging.
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| 34. |
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| 35. |
- Gao, H, et al.
(författare)
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CD36 Is a Marker of Human Adipocyte Progenitors with Pronounced Adipogenic and Triglyceride Accumulation Potential
- 2017
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Ingår i: Stem cells (Dayton, Ohio). - : Oxford University Press (OUP). - 1549-4918 .- 1066-5099. ; 35:7, s. 1799-1814
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Tidskriftsartikel (refereegranskat)abstract
- White adipose tissue (WAT) expands in part through adipogenesis, a process involving fat cell generation and fatty acid (FA) storage into triglycerides (TGs). Several findings suggest that inter-individual and regional variations in adipogenesis are linked to metabolic complications. We aimed to identify cellular markers that define human adipocyte progenitors (APs) with pronounced adipogenic/TG storage ability. Using an unbiased single cell screen of passaged human adipose-derived stromal cells (hADSCs), we identified cell clones with similar proliferation rates but discordant capabilities to undergo adipogenic differentiation. Transcriptomic analyses prior to induction of differentiation showed that adipogenic clones displayed a significantly higher expression of CD36, encoding the scavenger receptor CD36. CD36+ hADSCs, in comparison with CD36-cells, displayed almost complete adipogenic differentiation while CD36 RNAi attenuated lipid accumulation. Similar findings were observed in primary CD45-/CD34+/CD31-APs isolated from human WAT where the subpopulation of MSCA1+/CD36+ cells displayed a significantly higher differentiation degree/TG storage capacity than MSCA1+/CD36-cells. Functional analyses in vitro and ex vivo confirmed that CD36 conferred APs an increased capacity to take up FAs thereby facilitating terminal differentiation. Among primary APs from subcutaneous femoral, abdominal and visceral human WAT, the fraction of CD36+ cells was significantly higher in depots associated with higher adipogenesis and reduced metabolic risk (i.e., femoral WAT). We conclude that CD36 marks APs with pronounced adipogenic potential, most probably by facilitating lipid uptake. This may be of value in developing human adipocyte cell clones and possibly in linking regional variations in adipogenesis to metabolic phenotype.
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| 36. |
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| 37. |
- Genander, M, et al.
(författare)
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Ephrins negatively regulate cell proliferation in the epidermis and hair follicle
- 2010
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Ingår i: Stem cells (Dayton, Ohio). - : Oxford University Press (OUP). - 1549-4918 .- 1066-5099. ; 28:7, s. 1196-1205
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Tidskriftsartikel (refereegranskat)abstract
- Ephrins and their Eph tyrosine kinase receptors control many processes during embryonic development. They have more recently also been identified as important regulators of proliferation of stem/progenitor cells in the adult brain and intestine and have been implicated in tumorigenesis in a large number of tissues. We here describe the expression of a large number of ephrins and Eph receptors in the adult mouse skin. Disruption of the ephrin-Eph interaction in vivo with antagonists against the A or B class resulted in an approximate doubling of cell proliferation in the hair follicle and epidermis of adult mice. We conclude that ephrins are negative regulators of proliferation in the skin and that blocking the ephrin-Eph interaction may be an attractive strategy for regenerative therapies.
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| 38. |
- Grinnemo, Karl-Henrik, et al.
(författare)
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Costimulation blockade induces tolerance to HESC transplanted to the testis and induces regulatory T-cells to HESC transplanted into the heart
- 2008
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Ingår i: Stem Cells. - : Oxford University Press (OUP). - 1549-4918 .- 1066-5099. ; 26:7, s. 1850-1857
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Tidskriftsartikel (refereegranskat)abstract
- In order to study the ability of costimulation blockade to induce tolerance to human embryonic stem cells (HESC), severe combined immunodeficient (SCID), and immunocompetent C57BL/6 mice treated with costimulation blockade received intratesticular and intramyocardial HESC transplants. All SCID mice with intratesticular HESC transplants developed teratoma. When SCID mice were transplanted intramyocardially, only two of five mice developed teratoma-like tumors. C57BL/6 mice transplanted intratesticularly and treated with costimulation blockade all developed teratoma and were surrounded by CD4(+)CD25(+)Foxp3(+) T-cells, while isotype control treated recipients rejected their grafts. Most C57BL/6 mice transplanted intramyocardially and treated with costimulation blockade demonstrated lymphocytic infiltrates 1 month after transplantation, whereas one maintained its graft. Isolation of regulatory T-cells from intramyocardial transplanted recipients treated with costimulation blockade demonstrated specificity toward undifferentiated HESC and down-regulated naive T-cell activation toward HESC. These results demonstrate that costimulation blockade is sufficiently robust to induce tolerance to HESC in the immune-privileged environment of the testis. HESC specific regulatory T-cells developed to HESC transplanted to the heart and the success of transplantation was similar to that seen in SCID mice.
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| 39. |
- Hall, Vanessa, et al.
(författare)
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Using therapeutic cloning to fight human disease: A conundrum or reality?
- 2006
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Ingår i: Stem Cells. - : Oxford University Press (OUP). - 1549-4918 .- 1066-5099. ; 24:7, s. 1628-1637
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Tidskriftsartikel (refereegranskat)abstract
- The development and transplantation of autologous cells derived from nuclear transfer embryonic stem cell (NT-ESC) lines to treat patients suffering from disease has been termed therapeutic cloning. Human NT is still a developing field, with further research required to improve somatic cell NT and human embryonic stem cell differentiation to deliver safe and effective cell replacement therapies. Furthermore, the implications of transferring mitochondrial heteroplasmic cells, which may harbor aberrant epigenetic gene expression profiles, are of concern. The production of human NT-ESC lines also remains plagued by ethical dilemmas, societal concerns, and controversies. Recently, a number of alternate therapeutic strategies have been proposed to circumvent the moral implications surrounding human nuclear transfer. It will be critical to overcome these biological, legislative, and moral restraints to maximize the potential of this therapeutic strategy and to alleviate human disease.
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| 40. |
- Hansson, Mats G., et al.
(författare)
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Commentary: Isolated Stem Cells - Patentable as Cultural Artifacts?
- 2007
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Ingår i: Stem Cells. - : Oxford University Press (OUP). - 1066-5099 .- 1549-4918. ; 25:6, s. 1507-1510
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Tidskriftsartikel (refereegranskat)abstract
- This article argues that an isolated embryonic stem cell basically represents a cultural artifact that has no equivalent to cells of the embryo, and that it is likely that the isolation of adult stem cells has a similar consequence. An isolated stem cell could thus be distinguished as something other than the stem cell existing as part of a human body. Since isolation of stem cells implies modification, product patents should, where the results carry enough novelty, inventive step, and potential for industrial application, as a matter of principle be a viable option for patent authorities. Questions of morality, which may affect the patentability, should also be viewed in light of the distinction between isolated result and body part. At the same time, it is essential that patent authorities do not accept broad patent claims that will be detrimental to research. Disclosure of potential conflicts of interest is found at the end of this article.
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