We thank members of the Demaria lab for fruitful discussions, and Thijmen van Vliet for sharing data and protocol on the UV-induced senescence.

<ol>
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L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Targeting+DNA+topoisomerase+II+in+cancer+chemotherapy.">Targeting DNA topoisomerase II in cancer chemotherapy.</a> Nature Reviews Cancer. 9 (5), 338-350 (2009).</li><li>Pazolli, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chromatin+remodeling+underlies+the+senescence-+associated+secretory+phenotype+of+tumor+stromal+fibroblasts+that+supports+cancer+progression.">Chromatin remodeling underlies the senescence- associated secretory phenotype of tumor stromal fibroblasts that supports cancer progression.</a> Cancer Research. 72, 2251-2261 (2012).</li><li>Venturelli, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differential+induction+of+apoptosis+and+senescence+by+the+DNA+methyltransferase+inhibitors+5-azacytidine+and+5-aza-2'-deoxycytidine+in+solid+tumor+cells.">Differential induction of apoptosis and senescence by the DNA methyltransferase inhibitors 5-azacytidine and 5-aza-2'-deoxycytidine in solid tumor cells.</a> Molecular Cancer Therapeutics. 12, 2226-2236 (2013).</li><li>Tennant, J. 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The protocols explained here were optimized for human primary fibroblasts, particularly BJ and WI-38 cells. The protocols for replicative senescence, ionizing radiation and doxorubicin, have been successfully applied to other types of fibroblasts (HCA2 and IMR90) and in other cell types (namely neonatal melanocytes and keratinocytes or iPSC-derived cardiomyocytes) in our laboratory. However, adaptations for additional cell types can be optimized by adjusting some details such as the number of seeded cells, the methods an...

In 1961, Hayflick and Moorhead reported that primary fibroblasts in culture lose their proliferative potential after successive passages1. This process is caused by the sequential shortening of telomeres after each cell division. When telomeres reach a critically short length, they are recognized by the DNA-damage response (DDR) that activates an irreversible arrest of proliferation &#8212; also defined as replicative senescence. Replicative senescence is currently one of the many stimuli that are known to induce a state of permanent cell cycle arrest that renders cells insensitive both to mitogens and to apoptotic signals2,3. The senescence program is normally characterized by additional features including high lysosomal activity, mitochondrial dysfunction, nuclear changes, chromatin rearrangements, endoplasmic reticulum stress, DNA damage and a senescence-associated secretory phenotype (SASP)3,4. Senescent cells have multiple functions in the body: development, wound healing and tumor suppression2. Equally, they are known to play an important role in aging and, paradoxically, in tumor progression5. The negative, and partially contradictory, effects of senescence are often attributed to the SASP6.
Recently, it was shown that elimination of senescent cells from mice leads to lifespan extension and to elimination of many of the aging features7,8,9,10,11,12. In the same way, multiple drugs have been developed to either eliminate senescent cells (senolytics) or to target the SASP13,14. The anti-aging therapeutic potential has recently attracted more attention to the field.
The study of mechanisms associated to cellular senescence and the screenings for pharmacological interventions heavily rely on ex vivo models, particularly on human primary fibroblasts. While there are some common features activated by diverse senescence inducers, a large variability in the senescence phenotype is observed and dependent on various factors including cell type, stimulus and time point3,15,16,17. It is imperative to consider the heterogeneity for studying and targeting senescent cells. Therefore, this protocol aims to provide a series of methods used to induce senescence in primary fibroblasts by using different treatments. As it will be explained, the methods can easily be adapted to other cell types.
Apart from replicative senescence, we describe five other senescence-inducing treatments: ionizing radiation, ultraviolet (UV) radiation, doxorubicin, oxidative stress and epigenetic changes (namely promotion of histone acetylation or DNA demethylation). Both, ionizing radiation and UV-radiation cause direct DNA damage and, at the appropriate dose, trigger senescence18,19. Doxorubicin also causes senescence mainly through DNA damage by intercalating into the DNA and disrupting topoisomerase II function and thus halting DNA repair mechanisms20. The expression of genes essential for senescence is normally controlled by histone acetylation and DNA methylation. As a consequence, histone deacetylase inhibitors (e.g., sodium butyrate and SAHA) and DNA demethylating (e.g., 5-aza) agents trigger senescence in otherwise normal cells21,22.
Finally, four of the most common markers associated to senescent cells will be explained: activity of the senescence associated-&#946;-galactosidase (SA-&#946;-gal), rate of DNA synthesis by EdU incorporation assay, overexpression of the cell cycle regulators and cyclin-dependent kinase inhibitors p16 and p21, and overexpression and secretion of members of the SASP.

<table>
	<tbody>
		<tr>
			<td>DMEM Media - GlutaMAX</td>
			<td>Gibco</td>
			<td>31966-047</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum</td>
			<td>Hyclone</td>
			<td>SV30160.03</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin-Streptomycin (P/S; 10,000 U/ml)</td>
			<td>Lonza</td>
			<td>DE17-602E</td>
			<td></td>
		</tr>
		<tr>
			<td>Dimethyl Sulfoxide (DMSO)</td>
			<td>Sigma-Aldrich</td>
			<td>SC-202581</td>
			<td></td>
		</tr>
		<tr>
			<td>Nuclease-Free Water (not DEPC-Treated)</td>
			<td>Ambion</td>
			<td>AM9937</td>
			<td></td>
		</tr>
		<tr>
			<td>T75 flask</td>
			<td>Sarstedt</td>
			<td>833911002</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin/EDTA Solution</td>
			<td>Lonza</td>
			<td>CC-5012</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS tablets</td>
			<td>Gibco</td>
			<td>18912-014</td>
			<td></td>
		</tr>
		<tr>
			<td>1.5 ml microcentrifuge tubes</td>
			<td>Sigma-Aldrich</td>
			<td>T9661-1000EA</td>
			<td></td>
		</tr>
		<tr>
			<td>Corning&#160;15 mL centrifuge tubes</td>
			<td>Sigma-Aldrich</td>
			<td>CLS430791</td>
			<td></td>
		</tr>
		<tr>
			<td>6-well plate</td>
			<td>Sarstedt</td>
			<td>83.3920</td>
			<td></td>
		</tr>
		<tr>
			<td>24-well plate</td>
			<td>Sarstedt</td>
			<td>83.3922</td>
			<td></td>
		</tr>
		<tr>
			<td>13mm round coverslips</td>
			<td>Sarstedt</td>
			<td>83.1840.002</td>
			<td></td>
		</tr>
		<tr>
			<td>Steriflip</td>
			<td>Merck Chemicals</td>
			<td>SCGP00525</td>
			<td></td>
		</tr>
		<tr>
			<td>Cesium137-source</td>
			<td></td>
			<td></td>
			<td>IBL 637 Cesium-137&#947;-ray machine</td>
		</tr>
		<tr>
			<td>UV radiation chamber</td>
			<td></td>
			<td></td>
			<td>Opsytec, Dr. G&#246;bel BS-02</td>
		</tr>
		<tr>
			<td>Doxorubicin dihydrochloride&#160;</td>
			<td>BioAustralis Fine Chemicals</td>
			<td>BIA-D1202-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Hydrogen peroxide solution</td>
			<td>Sigma-Aldrich</td>
			<td>7722-84-1</td>
			<td></td>
		</tr>
		<tr>
			<td>5-aza-2&#8217;-deoxycytidine</td>
			<td>Sigma-Aldrich</td>
			<td>A3656</td>
			<td></td>
		</tr>
		<tr>
			<td>SAHA</td>
			<td>Sigma-Aldrich</td>
			<td>SML0061</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Butyrate&#160;</td>
			<td>Sigma-Aldrich</td>
			<td>B5887</td>
			<td></td>
		</tr>
		<tr>
			<td>X-gal (5-Bromo-4-chloro-3-indolyl-&#946;-D-galactopyranoside)</td>
			<td>Fisher Scientific</td>
			<td>7240-90-6</td>
			<td></td>
		</tr>
		<tr>
			<td>Citric acid monohydrate</td>
			<td>Sigma-Aldrich</td>
			<td>5949-29-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium dibasic phosphate</td>
			<td>Acros organics</td>
			<td>7782-85-6</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium ferrocyanide&#160;</td>
			<td>Fisher Scientific</td>
			<td>14459-95-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium ferricyanide</td>
			<td>Fisher Scientific</td>
			<td>13746-66-2</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Chloride</td>
			<td>Merck Millipore</td>
			<td>7647-14-5</td>
			<td></td>
		</tr>
		<tr>
			<td>Magnesium Chloride</td>
			<td>Fisher Chemicals</td>
			<td>7791-18-6</td>
			<td></td>
		</tr>
		<tr>
			<td>25% glutaraldehyde</td>
			<td>Fisher Scientific</td>
			<td>111-30-8,7732-18-5</td>
			<td></td>
		</tr>
		<tr>
			<td>16% formaldehyde (w/v)</td>
			<td>Thermo-Fisher Scientific</td>
			<td>28908</td>
			<td></td>
		</tr>
		<tr>
			<td>EdU (5-ethynyl-2&#8217;-deoxyuridine)</td>
			<td>Lumiprobe</td>
			<td>10540</td>
			<td></td>
		</tr>
		<tr>
			<td>Sulfo-Cyanine3 azide (Sulfo-Cy3-Azide)</td>
			<td>Lumiprobe</td>
			<td>D1330</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium ascorbate</td>
			<td>Sigma-Aldrich</td>
			<td>A4034</td>
			<td></td>
		</tr>
		<tr>
			<td>Copper(II) sulfate pentahydrate (Cu(II)SO4.5H2O)</td>
			<td>Sigma-Aldrich</td>
			<td>209198</td>
			<td></td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>Acros organics</td>
			<td>215682500</td>
			<td></td>
		</tr>
		<tr>
			<td>TRIS base</td>
			<td>Roche</td>
			<td>11814273001</td>
			<td></td>
		</tr>
		<tr>
			<td>LightCycler 480 Multiwell Plate 384, white&#160;</td>
			<td>Roche</td>
			<td>4729749001</td>
			<td></td>
		</tr>
		<tr>
			<td>Lightcycler 480 sealing foil&#160;</td>
			<td>Roche</td>
			<td>4729757001</td>
			<td></td>
		</tr>
		<tr>
			<td>Sensifast Probe Lo-ROX kit&#160;</td>
			<td>Bioline</td>
			<td>BIO-84020</td>
			<td></td>
		</tr>
		<tr>
			<td>UPL Probe Library</td>
			<td>Sigma-Aldrich</td>
			<td>Various</td>
			<td></td>
		</tr>
		<tr>
			<td>Human IL-6 DuoSet ELISA</td>
			<td>R&#38;D</td>
			<td>D6050</td>
			<td></td>
		</tr>
		<tr>
			<td>Bio-Rad TC20</td>
			<td>Bio-Rad</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Counting slides</td>
			<td>Bio-Rad</td>
			<td>145-0017</td>
			<td></td>
		</tr>
		<tr>
			<td>Dry incubator</td>
			<td>Thermo-Fisher Scientific</td>
			<td>Heratherm</td>
			<td></td>
		</tr>
		<tr>
			<td>Dimethylformamide</td>
			<td>Merck Millipore</td>
			<td>1.10983</td>
			<td></td>
		</tr>
		<tr>
			<td>Parafilm &#39;M&#39; laboratory film</td>
			<td>Bemis&#160;</td>
			<td>#PM992</td>
			<td></td>
		</tr>
		<tr>
			<td>Tweezers</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Needles</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

induction and validation of cellular senescence in primary human cells

Cellular senescence is a state of permanent cell cycle arrest activated in response to different damaging stimuli. Activation of cellular senescence is a hallmark of various pathophysiological conditions including tumor suppression, tissue remodeling and aging. The inducers of cellular senescence in vivo are still poorly characterized. However, a number of stimuli can be used to promote cellular senescence ex vivo. Among them, most common senescence-inducers are replicative exhaustion, ionizing and non-ionizing radiation, genotoxic drugs, oxidative stress, and demethylating and acetylating agents. Here, we will provide detailed instructions on how to use these stimuli to induce fibroblasts into senescence. This protocol can easily be adapted for different types of primary cells and cell lines, including cancer cells. We also describe different methods for the validation of senescence induction. In particular, we focus on measuring the activity of the lysosomal enzyme Senescence-Associated &#946;-galactosidase (SA-&#946;-gal), the rate of DNA synthesis using 5-ethynyl-2&#39;-deoxyuridine (EdU) incorporation assay, the levels of expression of the cell cycle inhibitors p16 and p21, and the expression and secretion of members of the Senescence-Associated Secretory Phenotype (SASP). Finally, we provide example results and discuss further applications of these protocols.

Enrichment of SA-&#946;-gal staining in senescent fibroblasts
&#914;-galactosidase (&#946;-gal) is a lysosomal enzyme that is expressed in all cells and that has an optimum pH of 4.025,26. However, during senescence, lysosomes increase in size and, consequently, senescent cells accumulate &#946;-gal. The increased amounts of this enzyme make it possible to detect its activi...

Watch this Scientific Journal Video about Induction and Validation of Cellular Senescence in Primary Human Cells at JoVE.com

Induction and Validation of Cellular Senescence in Primary Human Cells

Here, we discuss a series of protocols for induction and validation of cellular senescence in cultured cells. We focus on different senescence-inducing stimuli and describe the quantification of common senescence-associated markers. We provide technical details using fibroblasts as a model, but the protocols can be adapted to various cellular models.

Cellular senescence is a state of permanent cell cycle arrest activated in response to different damaging stimuli. Activation of cellular senescence is a ...

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16.5K Views.  University of Groningen, University Medical Center Groningen. Here, we discuss a series of protocols for induction and validation of cellular senescence in cultured cells. We focus on different senescence-inducing stimuli and describe the quantification of common senescence-associated markers. We provide technical details using fibroblasts as a model, but the protocols can be adapted to various cellular models.

Video: Induction and Validation of Cellular Senescence in Primary Human Cells

Induction of Protein Deletion Through In Utero Electroporation to Define Deficits in Neuronal Migration in Transgenic Models

Genetic deletion using the Cre-Lox system in transgenic mouse lines is a powerful tool used to study protein function. However, except in very specific Cre models, deletion of a protein throughout a tissue or cell population often leads to complex phenotypes resulting from multiple interacting mechanisms. Determining whether a phenotype results from disruption of a cell autonomous mechanism, which is intrinsic to the cell in question, or from a non-cell autonomous mechanism, which would result from impairment of that cell&#8217;s environment, can be difficult to discern. To gain insight into protein function in an in vivo context, in utero electroporation (IUE) enables gene deletion in a small subset of cells within the developing cortex or some other selected brain region. IUE can be used to target specific brain areas, including the dorsal telencephalon, medial telencephalon, hippocampus, or ganglionic eminence. This facilitates observation of the consequences of cell autonomous gene deletion in the context of a healthy environment. The goal of this protocol is to show how IUE can be used to analyze a defect in radial migration in a floxed transgenic mouse line, with an emphasis on distinguishing between the cell autonomous and non-cell autonomous effects of protein deletion. By comparing the phenotype resulting from gene deletion within the entire cortex versus IUE-mediated gene deletion in a limited cell population, greater insight into protein function in brain development can be obtained than by using either technique in isolation.

Induction of Protein Deletion Through In Utero Electroporation to Define Deficits in Neuronal Migration in Transgenic Models

Neuron migration is regulated by numerous cell autonomous and non-cell autonomous factors. This protocol shows how in utero electroporation can be used to determine whether a phenotype in a transgenic mouse is due to disruption of a cell intrinsic mechanism or impairment of interaction between the neuron and its environment.

Genetic deletion using the Cre-Lox system in transgenic mouse lines is a powerful tool used to study protein function. However, except in very specific ...

Isolation and Quantitative Immunocytochemical Characterization of Primary Myogenic Cells and Fibroblasts from Human Skeletal Muscle

The repair and regeneration of skeletal muscle requires the action of satellite cells, which are the resident muscle stem cells. These can be isolated from human muscle biopsy samples using enzymatic digestion and their myogenic properties studied in culture. Quantitatively, the two main adherent cell types obtained from enzymatic digestion are: (i) the satellite cells (termed myogenic cells or muscle precursor cells), identified initially as CD56+ and later as CD56+/desmin+ cells and (ii) muscle-derived fibroblasts, identified as CD56&#8211; and TE-7+. Fibroblasts proliferate very efficiently in culture and in mixed cell populations these cells may overrun myogenic cells to dominate the culture. The isolation and purification of different cell types from human muscle is thus an important methodological consideration when trying to investigate the innate behavior of either cell type in culture. Here we describe a system of sorting based on the gentle enzymatic digestion of cells using collagenase and dispase followed by magnetic activated cell sorting (MACS) which gives both a high purity (&#62;95% myogenic cells) and good yield (~2.8 x 106 &#177; 8.87 x 105 cells/g tissue after 7 days in vitro) for experiments in culture. This approach is based on incubating the mixed muscle-derived cell population with magnetic microbeads beads conjugated to an antibody against CD56 and then passing cells though a magnetic field. CD56+ cells bound to microbeads are retained by the field whereas CD56&#8211; cells pass unimpeded through the column. Cell suspensions from any stage of the sorting process can be plated and cultured. Following a given intervention, cell morphology, and the expression and localization of proteins including nuclear transcription factors can be quantified using immunofluorescent labeling with specific antibodies and an image processing and analysis package.

The main adherent cell types derived from human muscle are myogenic cells and fibroblasts. Here, cell populations are enriched using magnetic-activated cell sorting based on the CD56 antigen. Subsequent immunolabelling with specific antibodies and use of image analysis techniques allows quantification of cytoplasmic and nuclear characteristics in individual cells.

The repair and regeneration of skeletal muscle requires the action of satellite cells, which are the resident muscle stem cells. These can be isolated ...

Direct Induction of Human Neural Stem Cells from Peripheral Blood Hematopoietic Progenitor Cells

Human disease specific neuronal cultures are essential for generating in vitro models for human neurological diseases. However, the lack of access to primary human adult neural cultures raises unique challenges. Recent developments in induced pluripotent stem cells (iPSC) provides an alternative approach to derive neural cultures from skin fibroblasts through patient specific iPSC, but this process is labor intensive, requires special expertise and large amounts of resources, and can take several months. This prevents the wide application of this technology to the study of neurological diseases. To overcome some of these issues, we have developed a method to derive neural stem cells directly from human adult peripheral blood, bypassing the iPSC derivation process. Hematopoietic progenitor cells enriched from human adult peripheral blood were cultured in vitro and transfected with Sendai virus vectors containing transcriptional factors Sox2, Oct3/4, Klf4, and c-Myc. The transfection results in morphological changes in the cells which are further selected by using human neural progenitor medium containing basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF). The resulting cells are characterized by the expression for neural stem cell markers, such as nestin and SOX2. These neural stem cells could be further differentiated to neurons, astroglia and oligodendrocytes in specified differentiation media. Using easily accessible human peripheral blood samples, this method could be used to derive neural stem cells for further differentiation to neural cells for in vitro modeling of neurological disorders and may advance studies related to the pathogenesis and treatment of those diseases.

A method was developed to directly derive human neural stem cells from hematopoietic progenitor cells enriched from peripheral blood cells.

Human disease specific neuronal cultures are essential for generating in vitro models for human neurological diseases. However, the lack of access to ...

Direct Induction of Hemogenic Endothelium and Blood by Overexpression of Transcription Factors in Human Pluripotent Stem Cells

During development, hematopoietic cells arise from a specialized subset of endothelial cells, hemogenic endothelium (HE). Modeling HE development in vitro is essential for mechanistic studies of the endothelial-hematopoietic transition and hematopoietic specification. Here, we describe a method for the efficient induction of HE from human pluripotent stem cells (hPSCs) by way of overexpression of different sets of transcription factors. The combination of ETV2 and GATA1 or GATA2 TFs is used to induce HE with pan-myeloid potential, while a combination of GATA2 and TAL1 transcription factors allows for the production of HE with erythroid and megakaryocytic potential. The addition of LMO2 to GATA2 and TAL1 combination substantially accelerates differentiation and increases erythroid and megakaryocytic cells production. This method provides an efficient and rapid means of HE induction from hPSCs and allows for the observation of the endothelial-hematopoietic transition in a culture dish. The protocol includes hPSCs transduction procedures and post-transduction analysis of HE and blood progenitors.

This protocol describes the efficient induction of hemogenic endothelium and multipotential hematopoietic progenitors from human pluripotent stem cells via the forced expression of transcription factors.

During development, hematopoietic cells arise from a specialized subset of endothelial cells, hemogenic endothelium (HE). Modeling HE development in vitro ...

Directed Differentiation of Primitive and Definitive Hematopoietic Progenitors from Human Pluripotent Stem Cells

One of the major goals for regenerative medicine is the generation and maintenance of hematopoietic stem cells (HSCs) derived from human pluripotent stem cells (hPSCs). Until recently, efforts to differentiate hPSCs into HSCs have predominantly generated hematopoietic progenitors that lack HSC potential, and instead resemble yolk sac hematopoiesis.&#160;These resulting hematopoietic progenitors may have limited utility for in vitro disease modeling of various adult hematopoietic disorders, particularly those of the lymphoid lineages. However, we have recently described methods to generate erythro-myelo-lymphoid multilineage definitive hematopoietic progenitors from hPSCs using a stage-specific directed differentiation protocol, which we outline here. Through enzymatic dissociation of hPSCs on basement membrane matrix-coated plasticware, embryoid bodies (EBs) are formed. EBs are differentiated to mesoderm by recombinant BMP4, which is subsequently specified to the definitive hematopoietic program by the GSK3&#946; inhibitor, CHIR99021. Alternatively, primitive hematopoiesis is specified by the PORCN inhibitor, IWP2. Hematopoiesis is further driven through the addition of recombinant VEGF and supportive hematopoietic cytokines. The resulting hematopoietic progenitors generated using this method have the potential to be used for disease and developmental modeling, in vitro.

Here, we present human pluripotent stem cell (hPSC) culture protocols, used to differentiate hPSCs into CD34+ hematopoietic progenitors. This method uses stage-specific manipulation of canonical WNT signaling to specify cells exclusively to either the definitive or primitive hematopoietic program.

One of the major goals for regenerative medicine is the generation and maintenance of hematopoietic stem cells (HSCs) derived from human pluripotent stem ...

Induction of Mesenchymal-Epithelial Transitions in Sarcoma Cells

Phenotypic plasticity refers to a phenomenon in which cells transiently gain traits of another lineage. During carcinoma progression, phenotypic plasticity drives invasion, dissemination and metastasis. Indeed, while most of the studies of phenotypic plasticity have been in the context of epithelial-derived carcinomas, it turns out sarcomas, which are mesenchymal in origin, also exhibit phenotypic plasticity, with a subset of sarcomas undergoing a phenomenon that resembles a mesenchymal-epithelial transition (MET). Here, we developed a method comprising the miR-200 family and grainyhead-like 2 (GRHL2) to mimic this MET-like phenomenon observed in sarcoma patient samples.We sequentially express GRHL2 and the miR-200 family using cell transduction and transfection, respectively, to better understand the molecular underpinnings of these phenotypic transitions in sarcoma cells. Sarcoma cells expressing miR-200s and GRHL2 demonstrated enhanced epithelial characteristics in cell morphology and alteration of epithelial and mesenchymal biomarkers. Future studies using these methods can be used to better understand the phenotypic consequences of MET-like processes on sarcoma cells, such as migration, invasion, metastatic propensity, and therapy resistance.

We present here a cell culture method for inducing mesenchymal-epithelial transitions (MET) in sarcoma cells based on combined ectopic expression of microRNA-200 family members and grainyhead-like 2 (GRHL2). This method is suitable for better understanding the biological impact of phenotypic plasticity on cancer aggressiveness and treatments.

Phenotypic plasticity refers to a phenomenon in which cells transiently gain traits of another lineage. During carcinoma progression, phenotypic ...

Evaluation of Injury-induced Senescence and In Vivo Reprogramming in the Skeletal Muscle

Cellular senescence is a stress response that is characterized by a stable cellular growth arrest, which is important for many physiological and pathological processes, such as cancer and ageing. Recently, senescence has also been implicated in tissue repair and regeneration. Therefore, it has become increasingly critical to identify senescent cells in vivo. Senescence-associated &#946;-galactosidase (SA-&#946;-Gal) assay is the most widely used assay to detect senescent cells both in culture and in vivo. This assay is based on the increased lysosomal contents in the senescent cells, which allows the histochemical detection of lysosomal &#946;-galactosidase activity at suboptimum pH (6 or 5.5). In comparison with other assays, such as flow cytometry, this allows the identification of senescent cells in their resident environment, which offers valuable information such as the location relating to the tissue architecture, the morphology, and the possibility of coupling with other markers via immunohistochemistry&#160;(IHC). The major limitation of the SA-&#946;-Gal assay is the requirement of fresh or frozen samples.
Here, we present a detailed protocol to understand how cellular senescence promotes cellular plasticity and tissue regeneration in vivo. We use SA-&#946;-Gal to detect senescent cells in the skeletal muscle upon injury, which is a well-established system to study tissue regeneration. Moreover, we use&#160;IHC to detect Nanog, a marker of pluripotent stem cells, in a transgenic mouse model. This protocol enables us to examine and quantify cellular senescence in the context of induced cellular plasticity and in vivo reprogramming.

Evaluation of Injury-induced Senescence and In Vivo Reprogramming in the Skeletal Muscle

Here we present a detailed protocol to detect both senescent and pluripotent stem cells in the skeletal muscle upon injury while inducing in vivo reprogramming. This method is suitable for evaluating the role of cellular senescence during tissue regeneration and reprogramming in vivo.

Cellular senescence is a stress response that is characterized by a stable cellular growth arrest, which is important for many physiological and ...

In Vivo Tracking of Human Adipose-derived Mesenchymal Stem Cells in a Rat Knee Osteoarthritis Model with Fluorescent Lipophilic Membrane Dye

In order to support the clinical application of human adipose-derived mesenchymal stem cell (haMSC) therapy for knee osteoarthritis (KOA), we examined the efficacy of cell persistence and biodistribution of haMSCs in animal models. We demonstrated a method to label the cell membrane of haMSCs with lipophilic fluorescent dye. Subsequently, intra-articular injection of the labeled cells in rats with surgically induced KOA was monitored dynamically by an in vivo imaging system. We employed the lipophilic carbocyanines DiD (DilC18 (5)), a far-red fluorescent Dil (dialkylcarbocyanines) analog, which utilized a red laser to avoid excitation of the natural green autofluorescence from surrounding tissues. Furthermore, the red-shifted emission spectra of DiD allowed deep-tissue imaging in live animals and the labeling procedure caused no cytotoxic effects or functional damage to haMSCs. This approach has been shown to be an efficient tracking method for haMSCs in a rat KOA model. The application of this method could also be used to determine the optimal administration route and dosage of MSCs from other sources in pre-clinical studies.

In Vivo Tracking of Human Adipose-derived Mesenchymal Stem Cells in a Rat Knee Osteoarthritis Model with Fluorescent Lipophilic Membrane Dye

This protocol describes an efficient way to monitor the cell persistence and biodistribution of human adipose-derived mesenchymal stem cells (haMSCs) by far-red fluorescence labeling in a rat knee osteoarthritis (KOA) model via intra-articular (IA) injection.

In order to support the clinical application of human adipose-derived mesenchymal stem cell (haMSC) therapy for knee osteoarthritis (KOA), we examined the ...

Culture and Transfection of Zebrafish Primary Cells

Zebrafish embryos are transparent and develop rapidly outside the mother, thus allowing for excellent in vivo imaging of dynamic biological processes in an intact and developing vertebrate. However, the detailed imaging of the morphologies of distinct cell types and subcellular structures is limited in whole mounts. Therefore, we established an efficient and easy-to-use protocol to culture live primary cells from zebrafish embryos and adult tissue.
In brief, 2 dpf zebrafish embryos are dechorionated, deyolked, sterilized, and dissociated to single cells with collagenase. After a filtration step, primary cells are plated onto glass bottom dishes and cultivated for several days. Fresh cultures, as much as long term differenciated ones, can be used for high resolution confocal imaging studies. The culture contains different cell types, with striated myocytes and neurons being prominent on poly-L-lysine coating. To specifically label subcellular structures by fluorescent marker proteins, we also established an electroporation protocol which allows the transfection of plasmid DNA into different cell types, including neurons. Thus, in the presence of operator defined stimuli, complex cell behavior, and intracellular dynamics of primary zebrafish cells can be assessed with high spatial and temporal resolution. In addition, by using adult zebrafish brain, we demonstrate that the described dissociation technique, as well as the basic culturing conditions, also work for adult zebrafish tissue.

We present an efficient and easy-to-use protocol for preparing primary cell cultures of zebrafish embryos for transfection and live cell imaging as well as a protocol to prepare primary cells from adult zebrafish brain.

Zebrafish embryos are transparent and develop rapidly outside the mother, thus allowing for excellent in vivo imaging of dynamic biological processes in ...

A Quantitative Measurement of Reactive Oxygen Species and Senescence-associated Secretory Phenotype in Normal Human Fibroblasts During Oncogene-induced Senescence

Cellular senescence has been considered a state of irreversible growth arrest upon exhaustion of proliferative capacity or exposure to various stresses. Recent studies have extended the role of cellular senescence to various physiological processes, including development, wound healing, immune surveillance, and age-related tissue dysfunction. Although cell cycle arrest is a critical hallmark of cellular senescence, an increased intracellular reactive oxygen species (ROS) production has also been demonstrated to play an important role in the induction of cellular senescence. In addition, recent studies revealed that senescent cells exhibit potent paracrine activities on neighboring cells and tissues through a senescence-associated secretory phenotype (SASP). The sharp increase in interest regarding therapeutic strategies against cellular senescence emphasizes the need for a precise understanding of senescence mechanisms, including intracellular ROS and the SASP. Here, we describe protocols for quantitatively assessing intracellular ROS levels during H-Ras-induced cellular senescence using ROS-sensitive fluorescent dye and flow cytometry. In addition, we introduce sensitive techniques for the analysis of the induction of mRNA expression and secretion of SASP factors. These protocols can be applied to various cellular senescence models.

Intracellular ROS has been shown to play an important role in the induction of cellular senescence. Here, we describe a sensitive assay for quantifying ROS levels during cellular senescence. We also provide protocols for assessing the senescence-associated secretory phenotype, which reportedly contributes to various age-related dysfunctions.

Cellular senescence has been considered a state of irreversible growth arrest upon exhaustion of proliferative capacity or exposure to various stresses. ...