Editorial for Special Issue: iPS Cells (iPSCs) for Modelling and Treatment of Human Diseases

Human induced pluripotent stem cells (iPSCs) have evolved as a powerful tool to model diseases and study treatment possibilities [1] iPSCs have many advantages over classical disease models, such as animals, cell lines or patient-derived primary cells. They can be generated from any cell of the adult body with limited inconvenience for the patient, especially when urine cells are used as a starting material. Thus, it is easy to obtain cells from any desired genetic background; additionally, rare diseases can be studied using these cells. Using genome-editing techniques, isogenic controls and reporter cell lines can be obtained. These enable the investigation of the genetic basis for certain diseases, and reporter cell lines ensure that the desired cell type can be studied in isolation, as well as in combination with other relevant cell types for the organ. Being of human origin, they have the potential to outperform animal studies with respect to toxicological predictions, as drug metabolism varies substantially between species. However, until now, the lack of maturity of in vitro differentiated cells has limited their use in this field, and more research is needed to close this gap

Correction: Nguyen et al. The Nephrotoxin Puromycin Aminonucleoside Induces Injury in Kidney Organoids Differentiated from Induced Pluripotent Stem Cells. Cells 2022, 11, 635

In the original publication [...

Characterization of dermal fibroblast-derived iPSCs from a patient with low grade steatosis

AbstractPrimary fibroblasts from a low grade steatosis patient were reprogrammed by transduction of a combination of two episomal-based plasmids OCT4,SOX2, c-MYC and KLF4. iPSCs were characterized by immunocytochemistry, embryonic body-formation, DNA-fingerprint karyotype analysis and comparative transcriptome analyses with the human embryonic stem cell line H1 revealed a Pearsons correlation of 0.9251

A stem cell based in vitro model of NAFLD enables the analysis of patient specific individual metabolic adaptations in response to a high fat diet and AdipoRon interference

Non-alcoholic fatty liver disease (NAFLD) is a multifactorial disease. Its development and progression depend on genetically predisposed susceptibility of the patient towards several ‘hits’ that induce fat storage first and later inflammation and fibrosis. Here, we differentiated induced pluripotent stem cells (iPSCs) derived from four distinct donors with varying disease stages into hepatocyte like cells (HLCs) and determined fat storage as well as metabolic adaptations after stimulations with oleic acid. We could recapitulate the complex networks that control lipid and glucose metabolism and we identified distinct gene expression profiles related to the steatosis phenotype of the donor. In an attempt to reverse the steatotic phenotype, cells were treated with the small molecule AdipoRon, a synthetic analogue of adiponectin. Although the responses varied between cells lines, they suggest a general influence of AdipoRon on metabolism, transport, immune system, cell stress and signalling

Unrestricted somatic stem cells (USSC) from human umbilical cord blood display uncommitted epigenetic signatures of the major stem cell pluripotency genes

AbstractUnrestricted somatic stem cells (USSC) from human cord blood display a broad differentiation potential for ectodermal, mesodermal, and endodermal cell types. The molecular basis for these stem cell properties is unclear and unlike embryonic stem cells (ESC) none of the major stem cell factors OCT4, SOX2, and NANOG exhibits significant expression in USSC. Here, we report that these key stem cell genes hold an epigenetic state in between that of an ESC and a terminally differentiated cell type. DNA methylation analysis exhibits partial demethylation of the regulatory region of OCT4 and a demethylated state of the NANOG and SOX2 promoter/enhancer regions. Further genome-wide DNA methylation profiling identified a partially demethylated state of the telomerase gene hTERT. Moreover, none of the pluripotency factors exhibited a repressive histone signature. Notably, SOX2 exhibits a bivalent histone signature consisting of the opposing histone marks dimeH3K4 and trimeH3K27, which is typically found on genes that are "poised" for transcription. Consequently, ectopic expression of OCT4 in USSC led to rapid induction of expression of its known target gene SOX2. Our data suggest that incomplete epigenetic repression and a "poised" epigenetic status of pluripotency genes preserves the USSC potential to be able to react adequately to distinct differentiation and reprogramming cues

The Nephrotoxin Puromycin Aminonucleoside Induces Injury in Kidney Organoids Differentiated from Induced Pluripotent Stem Cells

Kidney diseases, including acute kidney injury (AKI) and chronic kidney disease (CKD), which can progress to end stage renal disease (ESRD), are a worldwide health burden. Organ transplantation or kidney dialysis are the only effective available therapeutic tools. Therefore, in vitro models of kidney diseases and the development of prospective therapeutic options are urgently needed. Within the kidney, the glomeruli are involved in blood filtration and waste excretion and are easily affected by changing cellular conditions. Puromycin aminonucleoside (PAN) is a nephrotoxin, which can be employed to induce acute glomerular damage and to model glomerular disease. For this reason, we generated kidney organoids from three iPSC lines and treated these with PAN in order to induce kidney injury. Morphological observations revealed the disruption of glomerular and tubular structures within the kidney organoids upon PAN treatment, which were confirmed by transcriptome analyses. Subsequent analyses revealed an upregulation of immune response as well as inflammatory and cell-death-related processes. We conclude that the treatment of iPSC-derived kidney organoids with PAN induces kidney injury mediated by an intertwined network of inflammation, cytoskeletal re-arrangement, DNA damage, apoptosis and cell death. Furthermore, urine-stem-cell-derived kidney organoids can be used to model kidney-associated diseases and drug discovery

Cell fate decisions of human iPSC-derived bipotential hepatoblasts depend on cell density

<div><p>During embryonic development bipotential hepatoblasts differentiate into hepatocytes and cholangiocytes- the two main cell types within the liver. Cell fate decision depends on elaborate interactions between distinct signalling pathways, namely Notch, WNT, TGFβ, and Hedgehog. Several <i>in vitro</i> protocols have been established to differentiate human pluripotent stem cells into either hepatocyte or cholangiocyte like cells (HLC/CLC) to enable disease modelling or drug screening. During HLC differentiation we observed the occurrence of epithelial cells with a phenotype divergent from the typical hepatic polygonal shape- we refer to these as endoderm derived epithelial cells (EDECs). These cells do not express the mature hepatocyte marker ALB or the progenitor marker AFP. However they express the cholangiocyte markers SOX9, OPN, CFTR as well as HNF4α, CK18 and CK19. Interestingly, they express both E Cadherin and Vimentin, two markers that are mutually exclusive, except for cancer cells. EDECs grow spontaneously under low density cell culture conditions and their occurrence was unaffected by interfering with the above mentioned signalling pathways.</p></div

Interference with various signalling pathways does not change cell fate.

<p>iPSCs were differentiated into EDECs. Directly after low-density splitting, small molecules were applied in order to interfere with signalling pathways important for differentiation into hepatocytes or cholangiocytes. (A-G) Immunocytochemistry for ALB (red) and CK19 (green). (A) DMSO control, (B) activation of WNT signalling with Chir99021, (C) inhibition of WNT signaling with PKF118-310, (D) activation of Hh signalling with Purmorphamine, (E) inhibition of Hh signalling with Cyclopamine-KAAD, (F) inhibition of TGFβ signalling with SB431242, (G) inhibition of TGFβ signalling with A-83-01. Scale bar: 100 μm.</p

Fibroblast-derived integration-free iPSC line ISRM-NBS1 from an 18-year-old Nijmegen Breakage Syndrome patient carrying the homozygous NBN c.657_661del5 mutation

Human fibroblasts cells from a female diagnosed with Nijmegen Breakage Syndrome (NBS) carrying the homozygous NBN c.657_661del5 mutation were used to generate integration-free induced pluripotent stem cells (iPSCs) by over-expressing episomal-based plasmids harbouring OCT4, SOX2, NANOG, KLF4, c-MYC and LIN28. The derived iPSC line – ISRM-NBS1 was defined as pluripotent based on (i) expression of pluripotency-associated markers (ii) embryoid body-based differentiation into cell types representative of the three germ layers and (iii) the similarity between the transcriptome of the iPSC line and the human embryonic stem cell line H1 with a Pearson correlation of 0.955