Stem cells
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Mitochondrial diseases display pathological phenotypes according to the mixture of mutant versus wild-type mitochondrial DNA (mtDNA), known as heteroplasmy. We herein examined the impact of nuclear reprogramming and clonal isolation of induced pluripotent stem cells (iPSC) on mitochondrial heteroplasmy. Patient-derived dermal fibroblasts with a prototypical mitochondrial deficiency diagnosed as mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) demonstrated mitochondrial dysfunction with reduced oxidative reserve due to heteroplasmy at position G13513A in the ND5 subunit of complex I. ⋯ On comparative differentiation of iPSC clones, improved cardiogenic yield was associated with iPSC clones containing lower heteroplasmy compared with isogenic clones with high heteroplasmy. Thus, mtDNA heteroplasmic segregation within patient-derived stem cell lines enables direct comparison of genotype/phenotype relationships in progenitor cells and lineage-restricted progeny, and indicates that cell fate decisions are regulated as a function of mtDNA mutation load. The novel nuclear reprogramming-based model system introduces a disease-in-a-dish tool to examine the impact of mutant genotypes for MELAS patients in bioengineered tissues and a cellular probe for molecular features of individual mitochondrial diseases.
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The studies of differentiation of mouse or human embryonic stem cells (hESCs) into specific cell types of the intestinal cells would provide insights to the understanding of intestinal development and ultimately yield cells for the use in future regenerative medicine. Here, using an in vitro differentiation procedure of pluripotent stem cells into definitive endoderm (DE), inductive signal pathways' guiding differentiation into intestinal cells was investigated. We found that activation of Wnt/β-catenin and inhibition of Notch signaling pathways, by simultaneous application of 6-bromoindirubin-3'-oxime (BIO), a glycogen synthase kinase-3β inhibitor, and N-[(3,5-Difluorophenyl)acetyl]-L-alanyl-2-phenylglycine-1,1-dimethylethyl ester (DAPT), a known γ-secretase inhibitor, efficiently induced intestinal differentiation of ESCs cultured on feeder cell. ⋯ Further investigation revealed that in the mouse ESCs, fibroblast growth factor (FGF) and bone morphogenetic protein (BMP) signaling act synergistically with BIO and DAPT to potentiate differentiation into the intestinal epithelium. However, in hESCs, FGF signaling inhibited, and BMP signaling did not affect differentiation into the intestinal epithelium. We concluded that Wnt and Notch signaling function to pattern the anterior-posterior axis of the DE and control intestinal differentiation.
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The use of mesenchymal stromal cells (MSCs) for treatment of bacterial infections, including systemic processes like sepsis, is an evolving field of investigation. This study was designed to investigate the potential use of MSCs, harvested from compact bone, and their interactions with the innate immune system, during polymicrobial sepsis induced by cecal ligation and puncture (CLP). We also wanted to elucidate the role of endogenous heme oxygenase (HO)-1 in MSCs during a systemic bacterial infection. ⋯ Moreover, after depleting neutrophils in recipient mice, the beneficial effects of MSCs were entirely lost, demonstrating the importance of neutrophils for this MSC response. MSCs also decreased multiple organ injury in susceptible HO-1(-/-) mice, when administered after the onset of sepsis. Taken together, these data demonstrate that the beneficial effects of treatment with MSCs after the onset of polymicrobial sepsis is not dependent on endogenous HO-1 expression, and that neutrophils are crucial for this therapeutic response.
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Alzheimer's disease (AD) is the leading cause of age-related dementia, affecting over 5 million people in the U. S. alone. AD patients suffer from progressive neurodegeneration that gradually impairs their memory, ability to learn, and carry out daily activities. ⋯ Stem cells may also offer a powerful new approach to model and study AD. Patient-derived induced pluripotent stem cells, for example, may help to advance our understanding of disease mechanisms. Likewise, studies of human embryonic and NSCs are helping to decipher the normal functions of AD-related genes; revealing intriguing roles in neural development.
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Culturing cells in three dimension (3D) provides an insight into their characteristics in vivo. We previously reported that human mesenchymal stem/stromal cells (hMSCs) cultured as 3D spheroids acquire enhanced anti-inflammatory properties. Here, we explored the effects of hMSC spheroids on macrophages that are critical cells in the regulation of inflammation. ⋯ Spheroids formed by human adult dermal fibroblasts produced low levels of PGE2 and displayed negligible anti-inflammatory effects on stimulated macrophages, suggesting the features as unique to hMSCs. Moreover, production of PGE2 by hMSC spheroids was dependent on the activity of caspases and NFκB activation in the hMSCs. The results indicated that hMSCs in 3D-spheroid cultures are self-activated, in part by intracellular stress responses, to produce PGE2 that can change stimulated macrophages from a primarily proinflammatory M1 phenotype to a more anti-inflammatory M2 phenotype.