Cultures Of Embryonic Fibroblasts Research Articles

Differences in phenotypes of normal and malignant cells concerning chromosomal fragility and ganglioside expression

The spontaneous chromosomal fragility was tested by light microscopy observation of metaphases from peripheral blood lymphocytes of 8 patients with malignancies and of 8 healthy controls. In the tested patients, a significantly higher frequency of the spontaneous chromosomal fragility was observed compared to the controls, especially in the centromere chromosomal regions. Of particular interest were interactions involving gangliosides, the reduced form of tri-peptide glutathione (GSH) and/or of tumor-suppressor protein HACE1. The average titers of gangliosides and of anti-ganglioside antibodies in extracts from experimental in vitro models of laboratory-incubated cultures of mouse embryonic 3T3 fibroblasts, of mouse malignant myeloma cells, as well as of mixed cultures of both cellular types, were determined after previous passing of each one through GSH-agarose columns about the “selection” of the molecules in each one of the described samples, possessing affinity to GSH. Additionally, the presence and expression of the tumor-suppressor gene HACE-1 in the genome of mouse embryonic stem cells (mESCs) and malignant human cervical carcinoma HeLa cells, both containing an additional copy of this gene, inserted by transfection with appropriate recombinant DNA vectors containing a copy of the tumor-suppressor gene, were tested. The developed experimental in vitro models show specific intermolecular interactions, which could prevent the disease development. Furthermore, a possibility about the production of antibodies/immunoglobulins by non-lymphoid cellular types was shown. Because the antibodies produced in this manner are outside the germinal centers in the specialized lymphoid tissues and organs, the control of their functions by small ions and molecules, such as gangliosides, is important.

Isolation and culture of chickenembryonic synovial fibroblasts.

Cells obtained from chicken embryos are often preferred for in vitro studies. These cells, which easily adapt to rapid and continuous growth in the appropriate cell culture environment, are thought to be one of the effective methods in the investigation of leg diseases that are frequently observed in poultry. Leg diseases, especially affecting the joints in chickens, cause locomotor problems and adversely affect animal welfare. In addition, they cause significant health problems and increase mortality. It is known that synovial fibroblasts play an important role in joint diseases. In this study, chicken embryonic synovial fibroblasts were isolated from tissue explants taken from the tibio-metatarsal joint region of brown layer chicken embryos. Characterization of cells was evaluated by immunocytochemistry and hemacolor staining. chicken embryonic synovial fibroblasts showed a strong positive reaction to the vimentin antibody. As a result of hemacolor staining, it was noted that the cell morphology was spindle-shaped. The absence of macrophages in chicken embryonic synovial fibroblast culture was confirmed by the carbon powder uptake. In this present study, we aim to present a useful cell culture protocol such as primary culture, passage, and characterization suitable for chicken embryonic synovial fibroblast to be used in the new scientific research.

Imaging Subcellular AMPK Activity Using an Excitation‐Ratiometric AMPK Activity Reporter

Adenosine monophosphate (AMP)-activated protein kinase (AMPK) is a master regulator of cellular metabolism, phosphorylating a variety of downstream targets throughout the cell. Subcellular AMPK activity results in regulation of glycolysis, lipid and protein biosynthesis, mitochondrial function, and gene expression. But how AMPK senses and responds to stimuli in a compartment-specific manner is not well understood, leaving an incomplete picture of compartmentalized AMPK activity. Key tools for studying subcellular AMPK activity are genetically encoded AMPK activity reporters (AMPKARs), which allow for the quantitative visualization of subcelluar AMPK activity. However, many AMPKARs suffer from poor dynamic range and sensitivity, limiting their application. I recently reported the development of a new excitation-ratiometric (ExRai) AMPKAR, a single-fluorophore AMPKAR with enhanced dynamic range for detection of subtle, subcellular AMPK activity. I used ExRai AMPKAR to study subcellular AMPK activity at several locations, including the lysosome and mitochondria, identifying new mechanisms for the regulation of AMPK activity. Here, I describe the use of ExRai AMPKAR to image subcellular AMPK activity in mouse embryonic fibroblasts using both widefield and confocal microscopy. I also describe the culture of mouse embryonic fibroblasts. Through the use of ExRai AMPKAR, subcellular AMPK activity can be illuminated to better understand how this central kinase regulates cellular metabolism. © 2023 The Author. Current Protocols published by Wiley Periodicals LLC. Basic Protocol: Imaging subcellular AMPK activity using ExRai AMPKAR Support Protocol 1: Culturing of mouse embryonic fibroblasts for live-cell imaging Support Protocol 2: Live-cell imaging of ExRai AMPKAR using confocal microscopy.

The telomerase activator TA-65 protects from cigarette smoke-induced small airway remodeling in mice through extra-telomeric effects

Small airway remodeling (SAR) is a key phenomenon of airflow obstruction in smokers, leading to chronic obstructive pulmonary disease (COPD). SAR results in an increased thickness of small airway walls, with a combination of peribronchiolar fibrosis with increased fibrous tissue and accumulation of mesenchymal and epithelial cells. SAR pathogenesis is still unclear but recent data suggest that alterations in telomerase activity could represent a possible underlying mechanism of SAR. Our study was dedicated to identify a potential protective role of TA-65, a pharmacological telomerase activator, in a cigarette smoke (CS) model of SAR in mice, and to further precise if extra-telomeric effects of telomerase, involving oxidative stress modulation, could explain it. C57BL/6J mice were daily exposed to air or CS during 4 weeks with or without a concomitant administration of TA-65 starting 7 days before CS exposure. Morphological analyses were performed, and mucus production, myofibroblast differentiation, collagen deposition, as well as transforming growth factor-β1 (TGF-β1) expression in the small airway walls were examined. In addition, the effects of TA-65 treatment on TGF-β expression, fibroblast-to-myofibroblast differentiation, reactive oxygen species (ROS) production and catalase expression and activity were evaluated in primary cultures of pulmonary fibroblasts and/or mouse embryonic fibroblasts in vitro. Exposure to CS during 4 weeks induced SAR in mice, characterized by small airway walls thickening and peribronchiolar fibrosis (increased deposition of collagen, expression of α-SMA in small airway walls), without mucus overproduction. Treatment of mice with TA-65 protected them from CS-induced SAR. This effect was associated with the prevention of CS-induced TGF-β expression in vivo, the blockade of TGF-β-induced myofibroblast differentiation, and the reduction of TGF-β-induced ROS production that correlates with an increase of catalase expression and activity. Our findings demonstrate that telomerase is a critical player of SAR, probably through extra-telomeric anti-oxidant effects, and therefore provide new insights in the understanding and treatment of COPD pathogenesis.

Stabilization of hESCs in two distinct substates along the continuum of pluripotency.

A detailed understanding of the developmental substates of human pluripotent stem cells (hPSCs) is needed to optimize their use in cell therapy and for modeling early development. Genetic instability and risk of tumorigenicity of primed hPSCs are well documented, but a systematic isogenic comparison between substates has not been performed. We derived four hESC lines in naive human stem cell medium (NHSM) and generated isogenic pairs of NHSM and primed cultures. Through phenotypic, transcriptomic, and methylation profiling, we identified changes that arose during the transition to a primed substate. Although early NHSM cultures displayed naive characteristics, including greater proliferation and clonogenic potential compared with primed cultures, they drifted toward a more primed-like substate over time, including accumulation of genetic abnormalities. Overall, we show that transcriptomic and epigenomic profiling can be used to place human pluripotent cultures along a developmental continuum and may inform their utility for clinical and research applications.

Влияние водорастворимых производных фуллерена С60 на уровень окислительного стресса и на транскрипционную активность генов, регулирующих про- и антиоксидантную активность эмбриональных фибробластов легких человека, культивируемых in vitro

The paper considers the effect of two water-soluble C60 fullerene derivatives modified with amino acid residues on the level of reactive oxygen species (ROS) in cultured human cells and on the transcriptional activity of genes that regulate pro- and antioxidant activity of cells. C60 fullerene derivatives with attached serine and phenibut amino acid residues were synthesized from C60Cl6 chlorofullerenes. Human embryonic lung fibroblast cultures were used in in vitro experiments. Various concentrations of fullerene derivatives were added to the culture medium, the cells were cultured in the presence of compounds from 1 to 72 hours. The level of ROS was determined using the dye 2,7-dichlorodihydrofluorescein diacetate (DCFH-DA), which is oxidized by free radicals to form fluorescent 2,7-dichlorofluorescein (DCF), by fluorescence microscopy, flow cytometry, and using a plate reader. The level of protein expression was determined by flow cytometry using specific antibodies. The level of gene expression was assessed by real-time polymerase chain reaction. It was shown that when the studied compounds are introduced into the cellular environment, they intensively absorb reactive oxygen species due to double conjugated bonds in the framework. At the same time, fullerene derivatives contribute to the development of secondary oxidative stress in cells 24 hours after administration. This effect occurs due to the activation of the NOX4 enzyme. In the cells of human embryonic lung fibroblasts, which were injected with the studied C60 fullerene derivatives, a correlation was found between the average value of the NOX4 enzyme protein and the level of reactive oxygen species. The lack of activation of the antioxidant transcription factor NRF2 upon incubation of human embryonic lung fibroblasts in the presence of C60 fullerene derivatives contributes to the development of secondary oxidative stress in cells.

Moving towards a novel therapeutic strategy for hyperammonemia that targets glutamine metabolism.

Patients with urea cycle disorders intermittently develop episodes of decompensation with hyperammonemia. Although such an episode is often associated with starvation and catabolism, its molecular basis is not fully understood. First, we attempted to elucidate the mechanism of such starvation-associated hyperammonemia. Using a mouse embryonic fibroblast (MEF) culture system, we found that glucose starvation increases ammonia production, and that this increase is associated with enhanced glutaminolysis. These results led us to focus on α-ketoglutarate (AKG), a glutamate dehydrogenase inhibitor, and a major anaplerotic metabolite. Hence, we sought to determine the effect of dimethyl α-ketoglutarate (DKG), a cell-permeable AKG analog, on MEFs and found that DKG mitigates ammonia production primarily by reducing flux through glutamate dehydrogenase. We also verified that DKG reduces ammonia in an NH4 Cl-challenged hyperammonemia mouse model and observed that DKG administration reduces plasma ammonia concentration to 22.8% of the mean value for control mice that received only NH4 Cl. In addition, we detected increases in ornithine concentration and in the ratio of ornithine to arginine following DKG treatment. We subsequently administered DKG intravenously to a newborn pig with hyperammonemia due to ornithine transcarbamylase deficiency and found that blood ammonia concentration declined significantly over time. We determined that this effect is associated with facilitated reductive amination and glutamine synthesis. Our present data indicate that energy starvation triggers hyperammonemia through enhanced glutaminolysis and that DKG reduces ammonia accumulation via pleiotropic mechanisms both in vitro and in vivo. Thus, cell-permeable forms of AKG are feasible candidates for a novel hyperammonemia treatment.

Functional genomics and the future of iPSCs in disease modeling.

SummaryInduced pluripotent stem cells (iPSCs) are valuable in disease modeling because of their potential to expand and differentiate into virtually any cell type and recapitulate key aspects of human biology. Functional genomics are genome-wide studies that aim to discover genotype-phenotype relationships, thereby revealing the impact of human genetic diversity on normal and pathophysiology. In this review, we make the case that human iPSCs (hiPSCs) are a powerful tool for functional genomics, since they provide an in vitro platform for the study of population genetics. We describe cutting-edge tools and strategies now available to researchers, including multi-omics technologies, advances in hiPSC culture techniques, and innovations in drug development. Functional genomics approaches based on hiPSCs hold great promise for advancing drug discovery, disease etiology, and the impact of genetic variation on human biology.

Invivo partial cellular reprogramming enhances liver plasticity and regeneration.

Mammals have limited regenerative capacity, whereas some vertebrates, like fish and salamanders, are able to regenerate their organs efficiently. The regeneration in these species depends on cell dedifferentiation followed by proliferation. We generate a mouse model that enables the inducible expression of the four Yamanaka factors (Oct-3/4, Sox2, Klf4, and c-Myc, or 4F) specifically in hepatocytes. Transient invivo 4F expression induces partial reprogramming of adult hepatocytes to a progenitor state and concomitantly increases cell proliferation. This is indicated by reduced expression of differentiated hepatic-lineage markers, an increase in markers of proliferation and chromatin modifiers, global changes in DNA accessibility, and an acquisition of liver stem and progenitor cell markers. Functionally, short-term expression of 4F enhances liver regenerative capacity through topoisomerase2-mediated partial reprogramming. Our results reveal that liver-specific 4F expression invivo induces cellular plasticity and counteracts liver failure, suggesting that partial reprogramming may represent an avenue for enhancing tissue regeneration.

Context-aware synthetic biology by controller design: Engineering the mammalian cell.

The rise of systems biology has ushered a new paradigm: the view of the cell as a system that processes environmental inputs to drive phenotypic outputs. Synthetic biology provides a complementary approach, allowing us to program cell behavior through the addition of synthetic genetic devices into the cellular processor. These devices, and the complex genetic circuits they compose, are engineered using a design-prototype-test cycle, allowing for predictable device performance to be achieved in a context-dependent manner. Within mammalian cells, context effects impact device performance at multiple scales, including the genetic, cellular, and extracellular levels. In order for synthetic genetic devices to achieve predictable behaviors, approaches to overcome context dependence are necessary. Here, we describe control systems approaches for achieving context-aware devices that are robust to context effects. We then consider cell fate programing as a case study to explore the potential impact of context-aware devices for regenerative medicine applications.

Mthfd2 Modulates Mitochondrial Function and DNA Repair to Maintain the Pluripotency of Mouse Stem Cells.

SummaryThe pluripotency of stem cells determines their developmental potential. While the pluripotency states of pluripotent stem cells are variable and interconvertible, the mechanisms underlying the acquisition and maintenance of pluripotency remain largely elusive. Here, we identified that methylenetetrahydrofolate dehydrogenase (NAD+-dependent), methenyltetrahydrofolate cyclohydrolase (Mthfd2) plays an essential role in maintaining embryonic stem cell pluripotency and promoting complete reprogramming of induced pluripotent stem cells. Mechanistically, in mitochondria, Mthfd2 maintains the integrity of the mitochondrial respiratory chain and prevents mitochondrial dysfunction. In the nucleus, Mthfd2 stabilizes the phosphorylation of EXO1 to support DNA end resection and promote homologous recombination repair. Our results revealed that Mthfd2 is a dual-function factor in determining the pluripotency of pluripotent stem cells through both mitochondrial and nuclear pathways, ultimately ensuring safe application of pluripotent stem cells.

ADAR1-Dependent RNA Editing Promotes MET and iPSC Reprogramming by Alleviating ER Stress.

RNA editing of adenosine to inosine (A to I) is catalyzed by ADAR1 and dramatically alters the cellular transcriptome, although its functional roles in somatic cell reprogramming are largely unexplored. Here, we show that loss of ADAR1-mediated A-to-I editing disrupts mesenchymal-to-epithelial transition (MET) during induced pluripotent stem cell (iPSC) reprogramming and impedes acquisition of induced pluripotency. Using chemical and genetic approaches, we show that absence of ADAR1-dependent RNA editinginducesaberrant innate immune responses through the double-stranded RNA (dsRNA) sensor MDA5, unleashing endoplasmic reticulum (ER) stress and hindering epithelial fate acquisition. We found that A-to-I editing impedes MDA5 sensing and sequestration of dsRNAs encoding membrane proteins, which promote ER homeostasis by activating the PERK-dependent unfolded protein response pathway to consequently facilitate MET. This study therefore establishes a critical role for ADAR1 and its A-to-I editing activity duringcell fate transitions and delineates a key regulatory layer underlying MET to control efficient reprogramming.

Rapid and Efficient Conversion of Human Fibroblasts into Functional Neurons by Small Molecules.

SummaryRecent studies have demonstrated that human astrocytes and fibroblasts can be directly converted into functional neurons by small molecules. However, fibroblasts, as a potentially better cell resource for transplantation, are not as easy to reprogram as astrocytes regarding their fate to neurons, and chemically induced neurons (iNs) with low efficiency from fibroblasts resulted in limited application for the treatment of neurological disorders, including depression. Here, we report that human fibroblasts can be efficiently and directly reprogrammed into glutamatergic neuron-like cells by serially exposing cells to a combination of small molecules. These iNs displayed neuronal transcriptional networks, and also exhibited mature firing patterns and formed functional synapses. Importantly, iNs could integrate into local circuits after transplantation into postnatal mouse brain. Our study provides a rapid and efficient transgene-free approach for chemically generating neuron-like cells from human fibroblasts. Furthermore, our approach offers strategies for disease modeling and drug discovery in central nervous system disorders.

Effects of substrate patterning on cellular spheroid growth and dynamics measured by gradient light interference microscopy (GLIM).

The development of three-dimensional (3D) cellular architectures during development and pathological processes involves intricate migratory patterns that are modulated by genetics and the surrounding microenvironment. The substrate composition of cell cultures has been demonstrated to influence growth, proliferation and migration in 2D. Here, we study the growth and dynamics of mouse embryonic fibroblast cultures patterned in a tissue sheet which then exhibits 3D growth. Using gradient light interference microscopy (GLIM), a label-free quantitative phase imaging approach, we explored the influence of geometry on cell growth patterns and rotational dynamics. We apply, for the first time to our knowledge, dispersion-relation phase spectroscopy (DPS) in polar coordinates to generate the radial and rotational cell mass-transport. Our data show that cells cultured on engineered substrates undergo rotational transport in a radially independent manner and exhibit faster vertical growth than the control, unpatterned cells. The use of GLIM and polar DPS provides a novel quantitative approach to studying the effects of spatially patterned substrates on cell motility and growth.

Defining Human Pluripotency.

Human pluripotent stem cells harbor the capacity to differentiate into cells from the three embryonic germ layers, and this ability grants them a central role in modeling human disorders and in the field of regenerative medicine. Here, we review pluripotency in human cells with respect to four different aspects: (1) embryonic development, (2) transcriptomes of pluripotent cell stages, (3) genes and pathways that reprogram somatic cells into pluripotent stem cells, and finally (4) the recent identification of the human pluripotent stem cell essentialome. These four aspects of pluripotency collectively culminate in a broader understanding of what makes a cell pluripotent.

PF531 TRANSFORMING ACTIVITIES OF THE NUP98-KMT2A FUSION GENE ASSOCIATED WITH MYELODYSPLASIA AND ACUTE MYELOID LEUKEMIA

Background: Inv (11)(p15q23) found in myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) was previously shown to lead to the expression of a fusion consisting of the N-terminal part of nucleoporin 98 (NUP98) and almost the entire open reading frame (ORF) of the lysine methyltransferase 2A (KMT2A, aka MLL1). Aims: To address the role of the NUP98-KMT2A fusion as a potential leukemogenic oncogene. Methods: To overcome the limitations related to the large size of the fusion ORF, we generated DOX-inducible transgenic iNUP98-KMT2A mice. We studied the effects of iNUP98-KMT2A expression in hematopoietic cells ex vivo in clonogenic assays; and in vivo by assessing blood counts, histology, and immunophenotyping as well as by competitive repopulation assays. In addition, we established primary mouse embryonic fibroblast (MEF) cultures to address the effects of iNUP98-KMT2A on cell cycle progression and cellular senescence. Results: In contrast to other KMT2A fusion such as MLL-AF9, induction of iNUP98-KMT2A did not alter differentiation but impaired growth of bone marrow (BM)-derived cells in vitro. Induction of iNUP98-KMT2A in vivo resulted in signs of disease after a highly variable latency of 13–106 weeks (median latency = 80 weeks, n = 22). Some symptomatic mice presented with increased white blood counts with morphological signs of dysplasia, reduced red blood cells, and increased apoptosis in the BM with signs of extramedullary hematopoiesis. In addition, we observed a 3-fold expansion of Lin−Sca-1+c-Kit+ (LSK) hematopoietic stem and progenitor cells (HSPC) in the BM of these mice. BM cells from symptomatic iNUP98-KMT2A mice had a competitive advantage in reconstitution assays. About 20% (5/22) of the mice on DOX presented with transplantable AML with elevated WBC counts and leukemic blasts in the peripheral blood with infiltration of multiple organs. Expression of iNUP98-KMT2A was associated with aberrant cell cycle progression in LSK cells from primary-induced mice. Similarly, iNUP98-KMT2A expression affected cell cycle progression and abrogated cellular senescence in MEF associated with aberrant expression of Sirt1, Tert, Rbl2, Twist1, Vim, and Prkcd that was also observed in BM cells. Notably, similar to patients with NUP98-KMT2A, and in contrast to other KMT2A fusions, primary AML cells from diseased iNUP98-KMT2A mice expressed very low levels of the Hox-A-B-C gene cluster. In addition, iNUP98-KMT2A leukemic blasts were resistant to the effects of pharmacological targeting of Menin/KMT2A interface or BET-family proteins. Summary/Conclusion: Our work shows that the NUP98-KMT2A fusion has oncogenic potential in mice leading to an MDS-like disease or AML. In contrast to other KMT2A fusions, NUP98-KMT2A does not primarily block differentiation and provide aberrant self-renewal potential, but alters cell cycle progression leading to dysplasia and impairs cellular senescence.

Reprogramming Captures the Genetic and Tumorigenic Properties of Neurofibromatosis Type 1 Plexiform Neurofibromas.

SummaryNeurofibromatosis type 1 (NF1) is a tumor predisposition genetic disease caused by mutations in the NF1 tumor suppressor gene. Plexiform neurofibromas (PNFs) are benign Schwann cell (SC) tumors of the peripheral nerve sheath that develop through NF1 inactivation and can progress toward a malignant soft tissue sarcoma. There is a lack of non-perishable model systems to investigate PNF development. We reprogrammed PNF-derived NF1(−/−) cells, descendants from the tumor originating cell. These NF1(−/−)-induced pluripotent stem cells (iPSCs) captured the genomic status of PNFs and were able to differentiate toward neural crest stem cells and further to SCs. iPSC-derived NF1(−/−) SCs exhibited a continuous high proliferation rate, poor myelination ability, and a tendency to form 3D spheres that expressed the same markers as their PNF-derived primary SC counterparts. They represent a valuable model to study and treat PNFs. PNF-derived iPSC lines were banked for making them available.

Generation and Culture of Mouse Embryonic Fibroblasts.

In addition to leukocytes, a variety of cells also participate in the innate immune response, including endothelial cells, epithelial cells, and fibroblasts. Thus, the study of these cells is highly relevant in broadening our understanding of mechanisms that modulate innate immunity. With the rise of genetically engineered animals, it is now common to confirm in vitro data acquired using immortalized cell lines with more physiologically relevant primary cells from these animals ex vivo. Indeed, many studies exploring innate immune system function employ mouse embryonic fibroblasts (MEFs). These cells are relatively simple to generate and are a powerful tool to explore regulatory networks, examine biochemical profiling of protein complexes, and investigate novel signaling pathways associated with innate immune system signaling. Here, we provide a robust protocol to isolate, maintain, and store primary MEFs. This protocol is designed for users with minimal experience using mouse models. We have also added precautions and common pitfalls associated with these procedures.

Kidney organoids—a new tool for kidney therapeutic development

Kidney organoids, derived from human pluripotent stem cells, have the potential to greatly facilitate drug development. Boreström etal. have used CRISPR/Cas9 to create kidney fluorescent lineage markers for SIX2 and NPHS1 to monitor the differentiation process to tubular and glomerular structures and optimize maturity. The convergence of "personalized" kidney organoids with genome editing and single-cell sequencing technology hold great promise to result in better insight to disease, better human cell disease models, more predictive toxicology, and potentially "clinical trials in a dish."

Mitochondrial Dysregulation and Impaired Autophagy in iPSC-Derived Dopaminergic Neurons of Multiple System Atrophy.

SummaryMultiple system atrophy (MSA) is a progressive neurodegenerative disease that affects several areas of the CNS, whose pathogenesis is still widely unclear and for which an effective treatment is lacking. We have generated induced pluripotent stem cell-derived dopaminergic neurons from four MSA patients and four healthy controls and from two monozygotic twins discordant for the disease. In this model, we have demonstrated an aberrant autophagic flow and a mitochondrial dysregulation involving respiratory chain activity, mitochondrial content, and CoQ10 biosynthesis. These defective mechanisms may contribute to the onset of the disease, representing potential therapeutic targets.