ARTICLE | doi:10.20944/preprints202205.0020.v1
Subject: Biology, Physiology Keywords: limb girdle muscular dystrophies; induced pluripotent stem cells; skeletal muscle cells; pathological modeling
Online: 5 May 2022 (03:44:03 CEST)
Limb girdle muscular dystrophies (LGMD), caused by mutations in 29 different genes, are the fourth most prevalent group of genetic muscle diseases, leading to progressive weakness and atrophy of the skeletal muscles. Although the link between LGMD and their genetic origins has been determined, LGMD still represent an unmet medical need. In this paper, we describe a platform for modeling LGMD based on the use of human induced pluripotent stem cells (hiPSC). Thanks to the self-renewing and pluripotency properties of hiPSC, this platform provides an alternative and renewable source of skeletal muscle cells (skMC) to primary, immortalized or overexpressing cells. We report that skMC derived from hiPSC express the majority of the genes and proteins causing LGMD. As a proof of concept, we demonstrate the importance of this cellular model for studying LGMDR9 by evaluating disease-specific phenotypes in skMC derived from hiPSC obtained from four patients.
ARTICLE | doi:10.20944/preprints201904.0200.v1
Subject: Medicine & Pharmacology, General Medical Research Keywords: adipose-derived; bone regeneration; cartilage regeneration; clinical application; clinical studies; differentiation; hair loss; induced pluripotent stem cells; maxillary sinus augmentation; osteoarthritis; pluripotency; regenerative
Online: 17 April 2019 (11:25:14 CEST)
Various tissue resident stem cells are receiving attention from basic scientists and clinicians as they hold certain promise for regenerative medicine. This paper is intended to clarify and facilitate the understanding, development and adoption of regenerative medicine in general and specifically of therapies based on unmodified, autologous adipose-derived regenerative cells (UA-ADRCs). To this end, results of landmark experiments on stem cells and stem cell therapy performed in the labs of the authors are summarized, the most intriguing of which are the following: (i) vascular associated mesenchymal stem cells (MSCs) can be isolated from different organs (adipose tissue, heart, skin, bone marrow and skeletal muscle) and differentiated into ectoderm, mesoderm and endoderm, providing significant support for the hypothesis of the existence of a small, ubiquitously distributed, universal vascular associated stem cell with full pluripotency; (ii) the orientation and differentiation of MSCs are driven by signals of the respective microenvironment; and (iii) these stem cells irrespective of the tissue origin exhibit full pluripotent differentiation potential without any prior genetic modification or the need for culturing. They can be obtained from a small amount of adipose tissue when using the appropriate technology for isolating the cells, and can be harvested from and re-applied to the same patient at the point of care without the need for complicated processing, manipulation, culturing, expensive equipment, or repeat interventions. These findings demonstrate the potential of UA-ADRCs for triggering the development of an entire new generation of medicine for the benefit of patients and of healthcare systems.
ARTICLE | doi:10.20944/preprints201804.0017.v1
Subject: Life Sciences, Cell & Developmental Biology Keywords: minicircle; induced pluripotent stem cells; chondrogenesis; chondrocyte; bone morphogenetic proteins; transforming growth factors
Online: 2 April 2018 (09:59:50 CEST)
The human degenerative cartilage has low regenerative potential. Chondrocyte transplantation offers a promising strategy for cartilage treatment and regeneration. Currently chondrogenesis using human pluripotent stem cells are accomplished using human recombinant growth factors. Here, we differentiated human induced pluripotent stem cells (hiPSCs) into chondrocytes and cartilage pellet using minicircle vectors. Minicircles are used as a non-viral gene delivery system for gene therapy in various diseases. Non-viral gene delivery can produce growth factors without integrating into the host genome. Minicircle vectors containing bone morphogenetic protein 2 (BMP2) and transforming growth factor, beta 3 (TGFβ3) were successfully generated and delivered to hiPSC-derived outgrowth (OG) cells. Cell pellets generated using minicircle-transfected OG cells successfully differentiated into chondrogenic lineage. Chondrogenic pellets transfected with growth factor-encoding minicircles effectively recovered osteochondral defect in rat models. Taken together, this work shows the potential application of minicircles in cartilage regeneration using hiPSCs.
ARTICLE | doi:10.20944/preprints202203.0143.v1
Subject: Life Sciences, Cell & Developmental Biology Keywords: human pluripotent stem cells; human embryonic stem cells; human induced pluripotent stem cells; cellular metabolism; oxygen; self-renewal; pluripotency; differentiation; volatile organic compounds; Selected ion flow tube-mass spectrometry
Online: 10 March 2022 (10:23:46 CET)
Human pluripotent stem cells (hPSCs) have widespread potential biomedical applications. There is a need for large-scale in vitro production of hPSCs, and optimal culture methods are vital in achieving this. Physiological oxygen (2% O2) improves key hPSCs attributes, including genomic integrity, viability, and clonogenicity, however, its impact on hPSC metabolism remains un-clear. Here, Selected Ion Flow Tube-Mass Spectrometry (SIFT-MS) was used to detect and quantify metabolic Volatile Organic Compounds (VOCs) in the headspace of hPSCs and their differentiated progeny. hPSCs were cultured in either 2% O2 or 21% O2. Media was collected from cell cultures and transferred into glass bottles for SIFT-MS measurement. The VOCs acetaldehyde and dimethyl sulfide (DMS)/ethanethiol were significantly increased in undifferentiated hPSCs compared to their differentiating counterparts, and these observations were more apparent in 2% O2. Pluripotent marker expression was consistent across both O2 concentrations tested. Transcript levels of ADH4, ADH5, and CYP2E1, encoding enzymes involved in converting ethanol to acetaldehyde, were upregulated in 2% O2, and chemical inhibition of ADH and CYP2E1 decreased acetaldehyde levels in hPSCs. Acetaldehyde and DMS/ethanethiol may be indicators of altered metabolism pathways in physiological oxygen culture conditions. The identification of non-destructive biomarkers for hPSC characterization has the potential to facilitate large-scale in vitro manufacture for future biomedical application.
Subject: Life Sciences, Biochemistry Keywords: Human induced pluripotent stem cells (hiPSCs); monoclonal antibodies; R-10G; R-17F; keratan sulfate; podocalyxin; keratanase II; endo-β-galactosidase
Online: 9 March 2021 (12:13:56 CET)
We developed two human induced pluripotent stem cell (hiPSC)/human embryonic stem cell-specific glycan-recognizing mouse antibodies, R-10G and R-17F, using the Tic (JCRB1331) hiPSC line as an antigen. R-10G recognizes a low-sulfate keratan sulfate, and R-17F recognizes lacto-N-fucopentaose-1. To evaluate the general characteristics of stem cell glycans, we used the hiPSC line 201B7 (HPS0063), a prototype iPSC line. Using an R-10G affinity column, an R-10G-binding protein was isolated. The protein yielded a single but very broad band from 480 to 1,236 kDa by blue native gel electrophoresis. After trypsin digestion, the protein was identified as podocalyxin by liquid chromatography/mass spectrometry. According to Western blotting, the protein reacted with R-10G and R-17F. The R-10G positive band was resistant to digestion with glycan-degrading enzymes, including peptide N-glycanase, but the intensity of the band was decreased significantly by digestion with keratanase, keratanase II, and endo-β-galactosidase, suggesting the R-10G epitope to be a keratan sulfate. These results suggest that keratan sulfate-type epitopes are shared by hiPSCs. However, the keratan sulfate from 201B7 cells contained a polylactosamine disaccharide unit (Galβ1-4GlcNAc) at a significant frequency, whereas that from Tic cells consisted mostly of keratan sulfate disaccharide units (Galβ1-4GlcNAc(6S)). In addition, the abundance of the R-10G epitope was significantly lower in 201B7 cells than in Tic cells.
REVIEW | doi:10.20944/preprints202004.0242.v1
Subject: Life Sciences, Other Keywords: extracellular vesicles; stem cells; induced pluripotent stem cells (iPSCs); regenerative medicine
Online: 15 April 2020 (10:08:44 CEST)
Regenerative medicine aims to repair damaged or missing cells, tissues or organs for the treatment of various diseases, poorly managed with conventional drugs and medical procedures. To date there are different approaches to obtain these results. Multimodal regenerative methods include transplant of healthy organs, tissues, or cells, body stimulation to activate a self healing response in damaged tissues, as well as the combined use of cells and bio-degradable scaffold to obtain functional tissues. Certainly, stem cells and derived products are promising tools in regenerative medicine due to their ability to induce de novo tissue formation and/or promote tissue and organ repair and regeneration. Currently, several studies have shown that the beneficial stem cell effects in damaged tissue restore are not depending on their engraftment and differentiation on the injury site, but rather to their paracrine activity. It is now well known that paracrine action of stem cells is due to their ability to release Extracellular Vesicles (EVs). EVs play a fundamental role in cell-to cell communication and are directly involved in tissue regeneration. In the present review, we tried to summarize the molecular mechanisms trough which EVs carry out their therapeutic action and their possible application for the treatment of several diseases.
REVIEW | doi:10.20944/preprints202207.0219.v1
Subject: Medicine & Pharmacology, Psychiatry & Mental Health Studies Keywords: personalized psychiatry; psychiatric disorders; induced pluripotent stem cells; brain organoids
Online: 14 July 2022 (11:46:51 CEST)
The polygenic and multifactorial nature of many psychiatric disorders has hampered the personalized medicine approach implementation in clinical practice. However, induced pluripotent stem cell (iPSC) technology has emerged as an innovative tool for patient-specific disease modeling to expand the pathophysiology knowledge and treatment perspectives in the last decade. Current technologies enable adult human somatic cell reprogramming into induced pluripotent stem cells (iPSCs) to generate neural cells and direct neural cell conversion to model organisms that exhibit phenotypes close to human diseases, thereby effectively representing relevant aspects of neuropsychiatric disorders. iPSCs reflect patient pathophysiology and pharmacological responsiveness, particularly when cultured under conditions that recapitulate spatial tissue organization in brain organoids. Recently, the application of iPSCs has been frequently associated with gene editing that targets the disease-causing gene to deepen the illness pathophysiology and conduct drug screening. Moreover, gene editing has provided a unique opportunity to repair the putative causative genetic lesions in patient-derived cells. Here, we review the use of iPSC technology to model and potentially treat neuropsychiatric disorders by illustrating the key studies on a series of mental disorders, including schizophrenia, major depression disorder, bipolar disorder, and autism spectrum disorder. The future perspective will involve the development of organ-on-a-chip platforms that control the microenvironmental conditions to reflect individual pathophysiological by adjusting physiochemical parameters according to personal health data. This strategy could open new ways to build a disease model that considers individual variability and tailors personalized treatments.
REVIEW | doi:10.20944/preprints201909.0079.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: Thromboangiitis Obliterans; inflammation; angiogenesis; immunomodulation; pluripotent stem cell; mesenchymal stem cell
Online: 7 September 2019 (00:31:05 CEST)
Buerger's disease or Thromboangiitis Obliterans (TAO) is a nonatherosclerotic segmental vascular disease which affects small and medium arteries and veins in the upper and lower extremities. Based on pathological findings, TAO can be considered as a distinct form of vasculitis that is most prevalent in young male smokers. There is no definitive cure for this disease as therapeutic modalities are limited in number and efficacy. Surgical bypass has limited utility and 24% of patients will ultimately require amputation. Recently, studies have shown that therapeutic angiogenesis and immunomodulatory approaches through the delivery of cells to target tissues are potential options for ischemic lesion treatment. In this review, we summarize the current knowledge of TAO treatment and provide an overview of stem cell-based treatment modalities.
ARTICLE | doi:10.20944/preprints201910.0229.v1
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: malignant melanoma; head and neck cancer; cancer stem cell; melanoma metastasis; induced pluripotent stem cell
Online: 19 October 2019 (17:15:36 CEST)
Cancer stem cells (CSCs) have been identified in many cancer types. This study identified and characterized CSCs in head and neck metastatic malignant melanoma (HNmMM) to regional lymph nodes using induced pluripotent stem cell (iPSC) markers. Immunohistochemical (IHC) staining performed on 20 HNmMM tissue samples demonstrated expression of iPSC markers OCT4, SOX2, KLF4 and c-MYC in all samples while NANOG was expressed at low levels in two samples. Immunofluorescence (IF) staining demonstrated an OCT4+/SOX2+/KLF4+/c-MYC+ CSC subpopulation within the tumor nests (TNs) and another within the peritumoral stroma (PTS) of HNmMM tissues. IF also showed expression of NANOG by some OCT4+/SOX2+/KLF4+/c-MYC+ cells within the TNs in an HNmMM tissue sample that expressed NANOG on IHC staining. In situ hybridization (n=6) and reverse-transcription quantitative polymerase chain reaction (n=5) on the HNmMM samples confirmed expression of all five iPSC markers. Western blotting of four primary cell lines derived from four of the 20 HNmMM tissue samples showed expression of SOX2, KLF4, and c-MYC but not OCT4 and NANOG, and three of these cell lines formed tumorspheres in vitro. We demonstrate the presence of two putative CSC subpopulations within HNmMM, which may be a novel therapeutic target in the treatment of this aggressive cancer.
ARTICLE | doi:10.20944/preprints201911.0162.v1
Subject: Life Sciences, Cell & Developmental Biology Keywords: human pluripotent stem cells; human stem cell-derived hepatocytes; in vitro; metabolic diseases; transcriptomics; maturation; characterization
Online: 14 November 2019 (11:24:24 CET)
There is a strong anticipated future for human pluripotent stem cell-derived hepatocytes (hiPS-HEP), but so far their use has been limited due to insufficient functionality. We investigated the potential of hiPS-HEP as an in vitro model for metabolic diseases by combining transcriptomics with multiple functional assays. The transcriptomics analysis revealed that 86% of the genes were expressed at similar levels in hiPS-HEP as in human primary hepatocytes (hphep). Adult characteristics of the hiPS-HEP were confirmed by the presence of important hepatocyte features, e.g. Albumin secretion and expression of major drug metabolizing genes. Normal energy metabolism is crucial for modeling metabolic diseases, and both transcriptomics data and functional assays showed that hiPS-HEP were similar to hphep regarding uptake of glucose, LDL and fatty acids. Importantly, the inflammatory state of the hiPS-HEP was low under standard conditions, but in response to lipid accumulation and ER stress the inflammation marker TNFα was upregulated. Furthermore, hiPS-HEP could be co-cultured with primary hepatic stellate cells both in 2D and in 3D spheroids, paving the way for using these co-cultures for modeling NASH. Taken together, hiPS-HEP have the potential to serve as an in vitro model for metabolic diseases. Furthermore, differently expressed genes identified in this study can serve as targets for future improvements of the hiPS-HEP.
ARTICLE | doi:10.20944/preprints202008.0091.v1
Subject: Life Sciences, Cell & Developmental Biology Keywords: induced pluripotent stem cells; disease modelling; neuronal differentiation; cholinergic neurons; Alzheimer’s disease; frontotemporal dementia
Online: 4 August 2020 (11:17:44 CEST)
The study of neurodegenerative diseases using pluripotent stem cells requires new methods to assess neurodevelopment and neurodegeneration of specific neuronal subtypes. The cholinergic system, characterized by its use of the neurotransmitter acetylcholine, is one of the first to degenerate in Alzheimer’s disease and is also affected in frontotemporal dementia. We developed a differentiation protocol to generate basal forebrain cholinergic neurons (BFCNs) from induced pluripotent stem cells (iPSCs) aided by the use of small molecule inhibitors and growth factors. Ten iPSC lines were successfully differentiated into BFCNs using this protocol. The neuronal cultures were characterised through RNA and protein expression, and functional analysis of neurons was confirmed by whole-cell patch clamp. We have developed a reliable protocol using only small molecule inhibitors and growth factors, while avoiding transfection or cell sorting methods, to achieve a BFCN culture that expresses the characteristic markers of cholinergic neurons.
ARTICLE | doi:10.20944/preprints201907.0347.v1
Subject: Medicine & Pharmacology, Ophthalmology Keywords: autograft; embryonic stem cells (ESC); growth factor (GF); hereditary retinal disease; induced pluripotent stem cells (iPSCs); Limoli retinal restoration technique (LRRT); mesenchymal stem cell (MSC); retinitis pigmentosa; spectral domain-optical coherence tomography (SD-OCT)
Online: 31 July 2019 (04:45:51 CEST)
To evaluate whether autologous mesenchymal cells, adipose derived stem cells and platelet-rich plasma, grafted into the supracoroideal space by surgical treatment according to Limoli retinal restoration technique (LRRT), can produce growth factors in order to exert a beneficial effect in retinitis pigmentosa (RP) patients. Twenty-one eyes underwent surgery and divided based on retinal foveal thickness ≤ 190 or >190 µm into group A and group B, respectively. The specific LRRT triad was grafted in a deep scleral pocket above the choroid of each eye. At 6-month follow-up, group B showed an improvement in residual close-up visus and sensitivity at microperimetry compared to group A. After an in-depth review of molecular biology studies concerning degenerative phenomena underlying the etiopathogenesis of RP, it can be confirmed that further research is needed on tapeto-retinal degenerations both from a clinical and molecular point of view to obtain better functional results. In particular, it is necessary to increase the number of patients, extend observation times, and treat subjects in the presence of still trophic retinal tissue to allow adequate biochemical and functional catering.
REVIEW | doi:10.20944/preprints201911.0170.v1
Subject: Biology, Other Keywords: PI3K signalling; cancer; stemness; pluripotent stem cells; development
Online: 15 November 2019 (03:59:00 CET)
The PI3K/AKT pathway is a key target in oncology where most efforts are focussed on phenotypes such as cell proliferation and survival. Comparatively little attention has been paid to PI3K in stemness regulation, despite the emerging link between acquisition of stem cell-like features and therapeutic failure in cancer. The aim of this review is to summarise current known and unknowns of PI3K-dependent stemness regulation, by integrating knowledge from the fields of developmental, signalling and cancer biology. Particular attention is given to the role of the PI3K pathway in pluripotent stem cells (PSCs) and the emerging parallels to dedifferentiated cancer cells with stem cell-like features. Compelling evidence suggests that PI3K/AKT signalling forms part of a ‘core molecular stemness programme’ in both mouse and human PSCs. In cancer, the oncogenic PIK3CAH1047R variant causes constitutive activation of the PI3K pathway and has recently been linked to increased stemness in a dose-dependent manner, similar to observations in mouse PSCs with heterozygous versus homozygous Pten loss. There is also evidence that the stemness phenotype may become ‘locked’ and thus independent of the original PI3K activation, posing limitations for the success of PI3K monotherapy in cancer.Ongoing therapeutic developments for PI3K-associated cancers may therefore benefit from a better understanding of the pathway’s two-layered and highly context-dependent regulation of cell growth versus stemness.
REVIEW | doi:10.20944/preprints202110.0251.v1
Subject: Life Sciences, Cell & Developmental Biology Keywords: pluripotent; embryo; stem cells; genomic stability; cell cycle; apoptosis; differentiation; cancer
Online: 18 October 2021 (15:12:11 CEST)
Abstract: Remarkably, the p53 transcription factor, referred to as “the guardian of the genome”, is not essential for mammalian development. Moreover, efforts to identify p53‑dependent developmental events have produced contradictory conclusions. Given the importance of pluripotent stem cells as models of mammalian development, and their applications in regenerative medicine and disease, resolving these conflicts is essential. Here we attempt to reconcile disparate data into justifiable conclusions predicated on reports that p53‑dependent transcription is first detected in late mouse blastocysts, that p53 activity first becomes potentially lethal during gastrulation, and that apoptosis does not depend on p53. Furthermore, p53 does not regulate expression of genes required for pluripotency in embryonic stem cells (ESCs); it contributes to ESC genomic stability and differentiation. Depending on conditions, p53 accelerates initiation of apoptosis in ESCs in response to DNA damage, but cell cycle arrest as well as the rate and extent of apoptosis in ESCs are p53-independent. In embryonic fibroblasts, p53 induces cell cycle arrest to allow repair of DNA damage, and cell senescence to prevent proliferation of cells with extensive damage.
ARTICLE | doi:10.20944/preprints202101.0552.v1
Subject: Biology, Anatomy & Morphology Keywords: organoid; induced pluripotent stem cell; Parkinson’s disease; neurotransmission; neuroimmunity; neuroinflammation; chikungunya; neuroinvasive
Online: 27 January 2021 (10:31:06 CET)
Arboviruses of medical and veterinary significance have been identified on all 7 continents with every human and animal population at risk for exposure. Like arboviruses, chronic neurodegenerative diseases like Alzheimer’s and Parkinson’s disease are found wherever there are humans. Viral parkinsonism has been documented for a variety of human pathogens though there are few studies that evaluate the effects of viral infection on degenerative neurological diseases. Significant differences in baseline gene and protein expression have been determined between Human Induced Pluripotent Stem Cell lines derived from a non-Parkinson’s disease individual and from an individual with reported Parkinson’s disease. While the organoids generated from each cell line were physically indistinguishable, significant differences were observed in gene and protein expression for neurotransmission and immunity. It was hypothesized that these inherent differences would impact cerebral organoid responses to viral infection. In this preliminary observational study, cerebral organoids from a non-Parkinson’s and Parkinson’s patient were infected with Chikungunya virus and observed for 2 weeks. Parkinson’s organoids lost mass and exhibited a dysfunctional antiviral response. Neurotransmission data from both non-Parkinson’s and Parkinson’s organoids had dysregulation of IL-1, IL-10, IL-6. These cytokines are associated with mood and could be contributing to persistent depression seen in patients following CHIKV infection. Both organoid types had increased expression of CCR5 and CXCL10 which are linked to demyelination, highlighting a potential mechanism for virus-associated parkinsonism. The dysfunctional antiviral response of Parkinson’s organoids highlights the need for more research in neurotropic infections in a neurologically compromised host.
ARTICLE | doi:10.20944/preprints202101.0480.v1
Subject: Biology, Anatomy & Morphology Keywords: organoid; induced pluripotent stem cell; Parkinson’s disease; neurotransmission; neuroimmunity; neuroinflammation; viral infection
Online: 25 January 2021 (10:55:03 CET)
The development of 3D cerebral brain organoids which accurately resemble aspects of the human brain permits a more accurate characterization of physiological processes and neurological diseases. Cerebral organoids can be grown from stem cell lines with various genetic backgrounds allowing multiple neurodegenerative diseases to be modeled. While dysfunction in neurotransmission of patients with neurodegenerative diseases is expected, the impact of chronic neurodegeneration on the response to viral infection of the CNS is poorly understood. For instance, several mosquito-borne viruses like Dengue virus and West Nile Virus cause post-viral parkinsonism. How CNS infection might impact a host with inherent CNS dysfunction such as Parkinson’s Disease in poorly understood. This preliminary, observational study aimed to understand dysfunction in intrinsic and innate expression of a patient with a neurodegenerative disease and a non-affected individual in relation to potential viral infection in the CNS. Cerebral organoids were generated from human induced pluripotent stem cells with a normal genetic background or with idiopathic Parkinson’s Disease. After differentiation and maturation, organoid size, gene expression and immunofluorescence were evaluated to assess neurotransmission and innate immunity. While there was no significant difference in size of the organoids with a normal or Parkinson’s genetic background, gene expression studies identified multiple differences in innate immunity and neurotransmission. Immunofluorescence also identified differences in protein expression related to neurotransmission and innate immunity. Of note, organoids derived from a Parkinson’s patient exhibited endogenous up-regulation of dopamine and muscarinic acetylcholine receptors, GABA, glycine, and glutamate targets, and the majority of cytokines. This expression pattern suggests a chronic state of neuroexcitation and neuroinflammation in this population of organoids.
REVIEW | doi:10.20944/preprints202006.0277.v2
Subject: Life Sciences, Cell & Developmental Biology Keywords: Diabetes; transcription factor; β-cell mass; pluripotent stem cells; pancreatic progenitors; cell therapy
Online: 19 October 2020 (16:04:27 CEST)
Understanding the biology underlying the mechanisms and pathways regulating pancreatic β-cell development is necessary to understand the pathology of diabetes mellitus (DM), which is characterized by the progressive reduction in insulin producing β-cell mass. Pluripotent stem cells (PSCs) can potentially offer an unlimited supply of functional β-cells for cellular therapy and disease modeling of DM. Homeobox protein NKX6.1 is a transcription factor (TF) that plays a critical role in pancreatic β-cell function and proliferation. In human pancreatic islet, NKX6.1 expression is exclusive toβ-cells and is undetectable in other islet cells. Several reports showed that activation of NKX6.1 in PSC-derived pancreatic progenitors (MPCs), expressing PDX1 (PDX1+/NKX6.1+), warrants their future commitment to monohormonal β-cells. However, further differentiation of MPCs lacking NKX6.1 expression (PDX1+/NKX6.1-) results in an undesirable generation of non-functional polyhormonal β-cells. The importance of NKX6.1 as a crucial regulator in MPC specification into functional β-cells directs attentions to further investigating its mechanism and enhancing NKX6.1 expression as a mean to increase β-cell function and mass. Here, we shed light on the role of NKX6.1 during pancreatic β-cell development and in directing the MPCs to functional monohormonal lineage. Furthermore, we address the transcriptional mechanisms and targets of NKX6.1 as well as its association with diabetes.
ARTICLE | doi:10.20944/preprints202301.0238.v1
Subject: Life Sciences, Cell & Developmental Biology Keywords: induced pluripotent stem cells; embryoid bodies; light-sheet microscopy; multicolor fluorescence in situ hybridization; chromosomes
Online: 13 January 2023 (07:10:46 CET)
Embryoid bodies (EBs) are multicellular three-dimensional (3D) aggregates generated from induced pluripotent stem cells (iPSCs) in suspension and serve as useful biological sources for many downstream applications. Imaging of live EBs has been hampered mainly due to the inherent limitations of the imaging techniques applied to date. This study aimed to image human iPSC (hiPSC) derived EBs to obtain their 3D volume, determining size, morphology, and cell viability from day 7 to 14 using Light Sheet Fluorescence Microscopy (LSFM). Furthermore, chromosomal stability was assessed using Multicolor fluorescence in situ hybridization (M-FISH) from day 8 to 14. EB volume increased from day 7 to 13 which, decreased at day 14. From day 7 to 11, the EBs mainly appeared spherical and morphed into an ellipsoidal shape by day 13. All EBs showed varied external morphologies and larger cavities at day 14. The EB karyotype was diploid 46XY at day 8 and exhibited a low level of aneuploidy from day 10 to 14. This study shows that an increase in cell death affects the morphology and chromosomal stability in EBs derived from hiPSC. We demonstrate that the combination of LSFM and M-FISH helps characterize EBs that will assist future stem cell therapies.
ARTICLE | doi:10.20944/preprints202211.0074.v1
Subject: Life Sciences, Cell & Developmental Biology Keywords: telomerase; TERT promoter; DNMT3B; pluripotent stem cells; characterization; epigenetic; meth-ylation; physiological oxygen; DNA methyltransferase
Online: 3 November 2022 (09:16:20 CET)
Telomere repeats at the ends of human chromosomes protect chromosomes from degradation, and telomerase has a prominent role in telomere maintenance. Telomerase also affects cell proliferation, DNA replication, differentiation, and tumourigenesis. TERT (telomerase reverse transcriptase enzyme) is the catalytic subunit of telomerase and is critical for enzyme activity. TERT promoter mutations and promoter methylation are strongly associated with increased telomerase activation in cancer cells. Notably, TERT and telomerase are downregulated in stem cells during their differentiation. Therefore, the link between differentiation and telomerase provides a valuable tool for studying the epigenetic regulation of TERT enzyme. Oxygen tension affects several cellular behaviours including proliferation, metabolic activity, stemness, and differentiation. The role of oxygen tension in driving promoter modifications of the TERT gene in embryonic stem cells (ESCs) is poorly understood either in vitro or in vivo. We adopted a monolayer ESCs differentiation model to explore the role of low, physiological, oxygen (physoxia) in the epigenetic regulation of telomerase and associated genes, including TERT, DNMTs, and HDACs. Cells were cultured in either air, a 2% O2 incubator, or a 2% O2 oxygen workstation to provide a fully defined 2% O2 environment. Pre-gassed media (pre-conditioned to 2% O2 in a HypoxyCool unit) was used in all 2% O2 experimentation. As anticipated, physoxia culture increased the proliferation rate and stemness of ESCs and a slower onset of differentiation in physoxia was evident. Further, downregulated TERT expression was correlated to reduced telomerase activity during differentiation. TERT expression and telomerase activity remained significantly elevated in physoxia during differentiation. A substantial increase in TERT promoter methylation levels was noted during differentiation. Chemical inhibition of DNMT3B reduced TERT promoter methylation and was associated with increased TERT gene and telomerase activity during differentiation. DNMT3B CHiP demonstrated that downregulated TERT expression and increased proximal promoter methylation were associated with DNMT3B binding to the promoter. In conclusion, we have demonstrated that DNMT3B can directly bind TERT promoter, change its methylation levels, and contribute to regulation of telomerase activity.
REVIEW | doi:10.20944/preprints202109.0189.v1
Subject: Life Sciences, Molecular Biology Keywords: circadian clock; epigenetic clock; aging; senescence; reprogramming; methylome; DNA methylation; CpG-islands; induced pluripotent stem cells
Online: 10 September 2021 (15:13:04 CEST)
This review summarizes current understanding of the interaction between circadian rhythms of gene expression and epigenetic clocks characterized by the specific profile of DNA methylation in CpG-islands which mirror the chronological age of individual cells and the entire organism. Basic mechanisms of regulation for circadian genes CLOCK- BMAL1 as well as downstream clock-controlled genes (ССG) are also discussed here. It has been shown that circadian rhythms operate by finely tuned regulation of transcription and rely on various epigenetic mechanisms including activation of enhancers / suppressors, acetylation / deacetylation of histones and other proteins as well as DNA methylation. Overall, up to 20% of all genes expressed by the cell are subject to expression oscillations associated with circadian rhythms. Also included in the review is a brief list of genes involved in the regulation of circadian rhythms, along with genes important for metabolic control, aging, and oncogenesis. Knocking out some of them (for example, Sirt1) accelerates the aging process, while overexpression of Sirt1, on the contrary, protects against age-related changes. Circadian regulators control a number of genes that activate the cell cycle (Wee1, c-Myc, p20, p21, and Cyclin D1) and regulate histone modification and DNA methylation. Approaches for determining the epigenetic age from methylation profiles across CpG islands in individual cells are described. DNA methylation, which characterizes the function of the epigenetic clock, appears to link together such key biological processes as regeneration and functioning of stem cells, aging and malignant transformation. Finally, main features of adult stem cell aging in stem cell niches and current possibilities for modulating the epigenetic clock as part of antiaging therapy are discussed.
REVIEW | doi:10.20944/preprints201703.0125.v1
Subject: Medicine & Pharmacology, Pathology & Pathobiology Keywords: Extracellular vesicles (EVs); Peptidylarginine deiminases (PADs); Chlor-amidine (Cl-Am); cancer; neurodegeneration; deimination; cytoskeleton; induced pluripotent stem cells (iPSCs); histone H3; epigenetics
Online: 16 March 2017 (17:54:15 CET)
Extracellular vesicle (EV) release, which occurs in most eukaryotic cells, has recently been associated with peptidylarginine deiminase (PAD)-driven protein deimination. Evidence points to the involvement of deiminated cytoskeletal proteins and changes in histone deimination. Both PADs and EVs are associated with various pathologies including cancers, autoimmune and neurodegenerative diseases. The elevated PAD expression observed in cancers may contribute to increase in EV shedding observed from cancer cells, contributing to cancer progression. Similarly, elevated PAD expression observed in neurodegenerative diseases may cause increased EV shedding and spread of neurodegenerative EV cargo, contributing to disease progression and pathologies. Pharmacological inhibition of PAD-mediated deimination using pan-PAD inhibitor Cl-amidine, reduced cellular EV release in prostate cancer cells, rendering them significantly more susceptible to chemotherapeutic drugs. Studies on models of central nervous system damage have demonstrated critical functional roles for PADs and neuroprotective effects using PAD inhibitors in vivo, while human neurodegenerative iPSC in vitro models showed evidence of increased protein deimination. Besides using refined PAD inhibitors to selectively manipulate EV biogenesis for novel combination therapies in cancer treatment, we also speculate how EV biogenesis could be targeted via the newly identified PAD-pathway to ameliorate neurodegenerative disease progression.
REVIEW | doi:10.20944/preprints201811.0018.v1
Subject: Life Sciences, Genetics Keywords: Duchenne muscular dystrophy (DMD); CRISPR/Cas9; exon skipping therapy; gene editing; human induced pluripotent stem cells (hiPSCs); immortalized patient muscle cells; mdx mice; humanized dystrophic mouse models; deltaE50-MD dog model
Online: 2 November 2018 (05:14:23 CET)
Duchenne muscular dystrophy (DMD) is a fatal X-linked recessive neuromuscular disease prevalent in 1 in 3500 to 5000 males worldwide. As a result of mutations that interrupt the reading frame of the dystrophin gene (DMD), DMD is characterized by a loss of dystrophin protein which leads to decreased muscle membrane integrity, which increases susceptibility to degeneration. CRISPR/Cas9 technology has garnered interest as an avenue for DMD therapy due to its potential for permanent exon skipping, which can restore the disrupted DMD reading frame in DMD and lead to dystrophin restoration. An RNA-guided DNA endonuclease system, CRISPR/Cas9 allows for the targeted editing of specific sequences in the genome. The efficacy and safety of CRISPR/Cas9 as a therapy for DMD has been evaluated by numerous studies in vitro and in vivo, with varying rates of success. Despite the potential of CRISPR/Cas9-mediated gene editing for the long-term treatment of DMD, its translation into the clinic is currently challenged by issues such as off-targeting, immune response activation, and sub-optimal in vivo delivery. Its nature as being mostly a personalized form of therapy also limits applicability to DMD patients, who exhibit a wide spectrum of mutations. This review summarizes the various CRISPR/Cas9 strategies that have been tested in vitro and in vivo for the treatment of DMD. Perspectives on the approach will be provided, and the challenges faced by CRISPR/Cas9 in its road to the clinic will be briefly discussed.
REVIEW | doi:10.20944/preprints202010.0578.v1
Subject: Biology, Anatomy & Morphology Keywords: Type 1 diabetes; insulin therapy; C-peptide; islet transplantation, mesenchymal stem cells; induced pluripotent stem cells; pancreatic β cell; gene therapy; β-cell regeneration and reprogramming, type 1 diabetes precision medicine, diabetes personalized care.
Online: 28 October 2020 (10:02:34 CET)
Type 1 diabetes affects millions of people globally and requires careful management to avoid serious long-term complications, including heart and kidney disease, stroke, and loss of sight. The present standard-of-care for type 1 diabetes is exogenic insulin substitutional therapy. The most advanced stretegies in this area is the development of hybrid-closed loop system and the producing of long-acting insulins. Progresses in stem cell therapies have started to revolutionize the care of patients with type 1 diabetes; however, significant challenges remain including the limited islets availability, difficulties in maintaining the viability, the heterogeneity within a complex pathology and in patients’ responses to treatment. On the way, a considerable amount of efforts in maximizing the islet transplantation effectiveness by controlling the advantageous of different stem cell approaches. With the availability and the use of big data, the concept of precision medicine is gaining wide attention worldwide and could bring the dream of “presonlaized” therapies as a reality in the near future. Here we review the current range of treatments available as well as recent pre-clinical breakthroughs in the field of personlaized medicine for type 1 diabetes.