The response of human induced pluripotent stem cells to cyclic temperature changes explored by BIO-AFM

AbstractHuman induced pluripotent stem cells (hiPSCs) are highly sensitive to extrinsic physical and biochemical signals from their extracellular microenvironments. In this study, we analyzed the effect of cyclic temperature changes on hiPSCs behaviors, especially by means of scanning force microscopy (BIO-AFM). The alternation in cellular mechanics, as well as the secretion and pattern of deposition of extracellular matrix (ECM) protein in hiPSCs were evaluated. The arrangement of the actin cytoskeleton changed with the variation of the temperature. The rearranged cytoskeleton architecture led to the subsequent changes in cell mechanics (Young's modulus of hiPSCs). With the exposure to the cyclic cold stimuli, an increase in the average surface roughness (Ra) and roughness mean square (RMS) was detected. This observation might be at least in part due to the upregulated secretion of Laminin α5 during repeated temporary cooling. The expression of pluripotent markers, NANOG and SOX2, was not impaired in hiPSCs, when exposed to the cyclic cold stimuli for 24 h. Our findings provide an insight into the effect of temperature on the hiPSC behaviors, which may contribute to a better understanding of the application of locally controlled therapeutic hypothermia. Graphic abstract The cyclic temperature changes, from 37 to 10 °C, rapidly increased the mechanical strength of human-induced pluripotent stem cells (hiPSCs), which could be explained by the re-arrangement of cytoskeletons. The capacity of hiPSCs to remodel the extracellular matrix was also altered by the repeated temporary cooling, as they exhibit an enhanced ability to physically remodulate and secrete the ECM components.

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Modeling Western Pacific Amyotrophic Lateral Sclerosis and Parkinsonism dementia Complex with Microglia Containing Cerebral Organoids Derived from Induced Pluripotent Stem Cells

10.1101/2021.08.06.455467 ◽

2021 ◽

Author(s):

Yiling Hong ◽

Xu Dong ◽

Lawrence Chang ◽

Mariann Chang ◽

Chen Xie ◽

...

Keyword(s):

Stem Cells ◽

Extracellular Matrix ◽

Amyotrophic Lateral Sclerosis ◽

Neurodegenerative Disease ◽

Induced Pluripotent Stem Cells ◽

Pluripotent Stem Cells ◽

M2 Microglia ◽

Matrix Organization ◽

Induced Pluripotent ◽

Lateral Sclerosis

Western Pacific Amyotrophic Lateral Sclerosis and Parkinsonism dementia Complex (ALS-PDC) is a neurodegenerative disease linked to the traditional consumption of cycad seeds by the Chamorro people of Guam. Little is known about the etiological role of cycad toxin in ALS-PDC. Patient derived induced pluripotent stem cells were derived from age and sex matched affected and unaffected patient lymphoid cells then differentiated into cerebral organoids. After three months, the ALS-PDC affected organoids were smaller, their neurons had less extensive neurite outgrowth, and the organoids had more reactive astrocytes and M1 microglia, fewer resting and M2 microglia, and more open extracellular space. Most of these phenomena could be recapitulated by exposing unaffected organoids to β-methylamino L-alanine (BMAA), a toxic amino acid produced by cyanobacteria living with cycad plants. Furthermore, ALS-PDC affected organoids exhibited an exacerbated neuroinflammatory response to BMAA exposure via activation of caspase1/NLRP3 inflammasome. A genome-wide transcriptome analysis of the organoids showed that the most down regulated pathways were taurine, alanine, aspartate, and glutamate metabolism; protein digestion; and absorption. The most down-regulated biological processes were type I interferon signaling, regulation of neuron differentiation and extracellular matrix organization. Our results suggested that the etiology of ALS-PDC is due to metabolic disorders that shifted microglia to a more proinflammatory M1 state instead of a non-inflammatory, repairing M2 state, which exacerbated inflammation and reduced extracellular matrix strength. Supplementation of transforming growth factor beta to ALS/PDC affected organoids increased the expression of interferon-induced transmembrane proteins (IFITMs) and restored M2 microglia populations and extracellular matrix organization. Organoids containing networks of neurons, astrocytes, microglia derived from iPSC with our protocol provides an excellent cellular model for neurodegenerative disease modeling.

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