1. Hypoxia induced by CoCl2 solution
Cobalt (II) Chloride hexahydrate (CoCl2 &bull; 6H2O, MW=237.9) is a chemical inducer of hypoxia-inducible 
factor-1.3 8. This product is soluble in water (100 mg/ml), yielding a clear, red solution. 
<ol>
<li>Prepare a 25mM stock solution in sterile dd water, (prepare immediately before use)</li> 
<li>Use CoCl2 at the final concentration of 100&mu;M in your regular cell culture media to induce hypoxia.</li>
<li>Add the CoCl2 containing media to your cells and incubate the cultures for 24hours in a conventional incubator (37&deg;C; 5% C02).</li>
</ol>
The above concentration works for the cell lines we have tested but each cell line should be tested at various concentrations (to establish a dose-dependent curve) as well as at various incubation times in order to limit drug related toxicity and optimize the assay.
2. Hypoxia induced in Modular Incubator Chamber
<ol>
<li>Prepare at least two identical (twin culture) cell cultures. Cell cultures can be in Flasks, plates or culture dishes. To open the chamber, first open the two white plastic clamps located on the tubes attached to the chamber (tubes used for the injection/ purging the hypoxic gas) and gently open the steel ring clamp.</li>
<li>Release the clamp. The lid and trays can now be removed.</li>
<li>Place the cell culture in the hypoxic chamber. Also place a Petri dish containing sterile water in the chamber to provide adequate humidification of the cultures.</li>
<li>Place the "twin" cell culture in normoxia as control.</li>
<li>Make sure your trays are secured and not moving, and then close the chamber with its lid. Correctly position the steel ring clamp to ensure the hermetical closure of the chamber and close it.</li>
<li>To create hypoxia, attach the tubing to a "hypoxia tank" containing a 1% O2 gas mixture. If you have a flow meter connected to your tank your chamber will be directly connected to it (gas tank-flow meter &#x2013;chamber). We use a flow meter incorporated in our regulator.</li>
<li>It is important to remove most if not all oxygen present in the chamber and in your media, to do so flush the chamber by opening the gas tank at a flow rate of 20 liters per minutes for 7-10 minutes; then quickly turn off the gas flow and completely close the chamber by closing both white clamps.</li>
<li>Return the chamber to a conventional incubator for the desired period of time. If you use large cultures, allow media in cultures to de-gas for 1- 2 hours and then repeat flush. 
The above steps are based on the constructor recommendations' (Billups-Rothenberg, Inc). Make sure you gas tank are properly secured at all time.</li> 
</ol>
Notes:
<ul>
<li>In order to eliminate the O2 contained in the media it is advised to re-gas the chamber once after 1-3hours.</li>
<li>For incubation time longer than 48hours it is also advised to re-gas the chamber.</li>
<li>Oxygen sensors (electrodes/manometer) that allow measurements of the O2 contained in cells/chamber will provide a more precise measurement of the intracellular/chamber O2 contain).</li>
<li>Culturing cells at various time lengths to make a time-curve would help determine the optimal time expression of HIF-1&alpha; in your particular cells.</li>
</ul>
3. Evaluation of Hypoxia
<ol>
<li>HIF-1 &alpha; detection by western blot.
<ol>
<li>Re-open your chamber as described in section 2.2 and immediately place your cultures on ice.</li>
<li>Lyse hypoxia treated and non-treated cells with 5% SDS solution in the plates then transfer the cell lyzate to tubes, sonicate, spindown the cell debris and collect the supernatant.</li>
<li>Measure protein concentration using BCA kit, prepare sample by adding loading buffer and heating at 95&deg;C for 5 min.</li>
<li>Electrophorese proteins on an 8% SDS-polyacrylamide gel and transfer to Nitrocellulose membranes.</li> 
<li>Block the membrane in PBS containing 5% non-fat dry milk and 0.1% Tween 20 at room temperature for 1 hour or at 4&deg;C overnight on shaker.</li>
<li>Immunoblot overnight with anti-HIF-1&alpha; primary monoclonal antibody (1/600) in the same buffer at 4 &deg;C.</li> 
<li>Wash 3 times in PBS containing 0.1% Tween 20 at room temperature, 5min each time and incubate with HRP-secondary antibody (1/2000) in PBS + 0.1% Tween 20 for 45 min.</li>
<li>Wash 3 times in PBS containing 0.1% Tween 20 at room temperature, 5min / time.</li>
<li>Use Pierce ECL kit and X-ray film to show the protein band</li>
</ol>
</li>
<li>Hypoxia Responsive Element (HRE). 
HIF-1&alpha; regulates numerous genes (i.e VEGF, EPO) by binding to a sequence called Hypoxia Regulating Element (HRE). Using HRE associated to a marker gene it is 
possible to detect HIF activity 9. To use this method, first you need to transfect your cells with a HRE-luciferase 
plasmid using a transfection method adapted to your cells. For example we used Lipofectamine 2000. Cells need to be transfected at least 4 hours before 
to be incubated in hypoxia and normoxia. This time allows the DNA to enter the cells so that this first step is not affected by hypoxia. The luciferase signal 
is detected using a Luciferase Assay Kit.
<ol>
<li>Incubate your HRE-transfected cells in hypoxia in modular chamber or use HRE-transfected cells incubated with CoCl2, include a normoxia control.</li>
<li>After the desired incubation period, remove growth medium from cells.</li>
<li>Rinse cells in PBS, remove the PBS.</li>
<li>Dispense 400&mu;l 1X lysis reagent into culture dish and scrape the attached cells, then transfer them to a micro tube.</li> 
<li>Pellet debris by brief centrifugation.</li>
<li>Mix 20&mu;l of cell lysates supernatant with 100&mu;l of Luciferase Assay Reagent and measure the luminescence using a luminometer.</li>
</ol>
</li>
</ol>
4. Representative Results:
In K562 cells (human leukemia cell line) cultured 2 days in low oxygen, compared to normoxia, hypoxia induces an increase of HIF-1&alpha; protein that was detected by western blot (Figure 1). 
Using HRE-luciferase modified 293 cells (embryonic kidney cell line) cultured in hypoxia, a significant increased of HIF-1&alpha; activity was detected in hypoxic cells (Figure 2).
<img src="/files/ftp_upload/2899/2899fig1.jpg" alt="Figure 1"/> 
Figure 1: Increase HIF-1&alpha; in hypoxic cells. K562 cells were culture in normoxia and hypoxia (hypoxic chamber) for 48 hrs and analyzed by western blot using an antibody specific for HIF-1&alpha;. An antibody specific for actin was used for the loading control. 
<img src="/files/ftp_upload/2899/2899fig2.jpg" alt="Figure 2"/> 
Figure2: HIF-1&alpha; activity. HRE-luciferase modified 293 cells were cultured in hypoxia and normoxia for 48 hrs and then lysed to detect luciferase signal using a luciferase assay kit and a luminometer. Results are expressed as the relative luminescence unit (RLU).

<ol>
	<li>Swinson, D. E., O'Byrne, K. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interactions+between+hypoxia+and+epidermal+growth+factor+receptor+in+non-small-cell+lung+cancer.">Interactions between hypoxia and epidermal growth factor receptor in non-small-cell lung cancer.</a> Clin Lung Cancer. 7, 250-256 (2006).</li><li>van Laarhoven, H. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hypoxia+in+relation+to+vasculature+and+proliferation+in+liver+metastases+in+patients+with+colorectal+cancer.">Hypoxia in relation to vasculature and proliferation in liver metastases in patients with colorectal cancer.</a> Int J Radiat Oncol Biol Phys. 64, 473-482 (2006).</li><li>Hockel, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intratumoral+pO2+predicts+survival+in+advanced+cancer+of+the+uterine+cervix.">Intratumoral pO2 predicts survival in advanced cancer of the uterine cervix.</a> Radiother Oncol. 26, 45-50 (1993).</li><li>Semenza, G. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=HIF-1+and+human+disease:+one+highly+involved+factor.">HIF-1 and human disease: one highly involved factor.</a> Genes Dev. 14, 1983-1991 (2000).</li><li>Semenza, G. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hypoxia-inducible+factor+1:+master+regulator+of+O2+homeostasis.">Hypoxia-inducible factor 1: master regulator of O2 homeostasis.</a> Curr Opin Genet Dev. 8, 588-594 (1998).</li><li>Tatum, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hypoxia:+importance+in+tumor+biology,+noninvasive+measurement+by+imaging,+and+value+of+its+measurement+in+the+management+of+cancer+therapy.">Hypoxia: importance in tumor biology, noninvasive measurement by imaging, and value of its measurement in the management of cancer therapy.</a> Int J Radiat Biol. 82, 699-757 (2006).</li><li>Brahimi-Horn, M. C., Pouyssegur, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=HIF+at+a+glance.">HIF at a glance.</a> J Cell Sci. 122, 1055-1057 (2009).</li><li>Piret, J. P., Mottet, D., Raes, M., Michiels, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CoCl2,+a+chemical+inducer+of+hypoxia-inducible+factor-1,+and+hypoxia+reduce+apoptotic+cell+death+in+hepatoma+cell+line+HepG2.">CoCl2, a chemical inducer of hypoxia-inducible factor-1, and hypoxia reduce apoptotic cell death in hepatoma cell line HepG2.</a> Ann N Y Acad Sci. 973, 443-447 (2002).</li><li>Emerling, B. M., Weinberg, F., Liu, J. L., Mak, T. W., Chandel, N. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=PTEN+regulates+p300-dependent+hypoxia-inducible+factor+1+transcriptional+activity+through+Forkhead+transcription+factor+3a+(FOXO3a).">PTEN regulates p300-dependent hypoxia-inducible factor 1 transcriptional activity through Forkhead transcription factor 3a (FOXO3a).</a> Proc Natl Acad Sci U S A. 105, 2622-2627 (2008).</li></ol>

No conflicts of interest declared.

Cell proliferation and viability in hypoxic conditions vary a lot depending on the cell types. Therefore, you should adjust the cell number or the number of cultures plates you start with to make sure you will have enough cells/proteins for your experiments. 
The Cobalt Chloride method has the advantage to be inexpensive and fast. This product mimics hypoxia by inducing HIF-1/3&alpha; but can also regulate other genes, make sure this product is adapted to your project by checking what other effects it could have on the function and phenotype of your particular cells independently of the "mimic-hypoxic" effect. Another drug also used to mimic hypoxia is Deferoxamine mesylate (DFO, used at 100 &mu;M final concentration). The use of these drugs allows the experimentator to open the culture plate/dish/flask many times without affecting the "hypoxic condition".
The level of oxygen contained in the gas mixture can vary depending on your experiments and cell types as hypoxia values vary depending on the tissues and cell types. Indeed, some cells are hypoxic in 5% O2 other need less than 1% O2 to be hypoxic. 5%CO2 is added to the gas mixture to stabilize the pH of the cultures, the rest of the gas is usually Nitrogen.
Hypoxic chambers have the advantage of not using drugs that can alternate cell behavior independently of the oxygen tension. However, not all types of experimentation can be done as oxygen re-enters the chamber at each opening and thus lessens hypoxia. You should consider this factor in your experiments; hypoxia/re-oxygenation is a specific condition that can affect some cell types. An alternative is to use hypoxia workstations (connected to pre-mixed gas tanks or to gas mixing systems) or larger hypoxia incubator (hypoxia processing chamber with glove box) that allows the experimentation to change media and manipulate cells in continuous hypoxic environment. Various hypoxic chambers have been commercialized over the past decade and should be chosen according to your laboratory used, projects, space, size, and budget. Always ensure the good use and condition of your chamber to guarantee correct culture conditions. In general when using a chamber, the level of hypoxia can be modulated by selecting the various gas mixes (i.e. 1%, 5% 10% oxygen).
Regarding the detection of HIF-1&alpha;, it is important to know that some cancer cell line express HIF-1&alpha; in normoxia. It is therefore critical to use a normoxia-control to determine the basal level of HIF in these cell lines. HIF-1&alpha; can also be present in normoxia in non-malignant cells following cell stimulation or stress. This could also occur if these cells are starved, make sure your cell cultures are properly feed and maintained.

<table border="1">
 <tbody>
 <tr>
 <th>Name of the reagent</th>
 <th>Company</th>
 <th>Catalogue number</th>
 </tr>
 <tr>
 <td>Anti-HIF-1&alpha;</td>
 <td>Invitrogen</td>
 <td>458400</td>
 </tr>
 <tr>
 <td>Cobalt (II) Chloride </td>
 <td>Sigma</td>
 <td>C8661-25G</td>
 </tr>
 <tr>
 <td>Incubator Chamber</td>
 <td>Billups-rothenberg </td>
 <td>MIC-101</td>
 </tr>
 <tr>
 <td>HRE-Luciferase plasmid</td>
 <td>Adgene</td>
 <td>Plasmid 26731</td>
 </tr> 
 </tbody>
</table>

induction and testing of hypoxia in cell culture

Hypoxia is defined as the reduction or lack of oxygen in organs, tissues, or cells. This decrease of oxygen tension can be due to a reduced supply in oxygen (causes include insufficient blood vessel network, defective blood vessel, and anemia) or to an increased consumption of oxygen relative to the supply (caused by a sudden higher cell proliferation rate). Hypoxia can be physiologic or pathologic such as in solid cancers 1-3, rheumatoid arthritis, atherosclerosis etc&#x2026; Each tissues and cells have a different ability to adapt to this new condition. During hypoxia, hypoxia inducible factor alpha (HIF) is stabilized and regulates various genes such as those involved in angiogenesis or transport of oxygen 4. The stabilization of this protein is a hallmark of hypoxia, therefore detecting HIF is routinely used to screen for hypoxia 5-7. 
In this article, we propose two simple methods to induce hypoxia in mammalian cell cultures and simple tests to evaluate the hypoxic status of these cells.

Watch this Scientific Journal Video about Induction and Testing of Hypoxia in Cell Culture at JoVE.com

Induction and Testing of Hypoxia in Cell Culture

Here we propose simple methods to induce hypoxia in cell cultures and simple tests to evaluate the hypoxic status of the cultures.

Hypoxia is defined as the reduction or lack of oxygen in organs, tissues, or cells.  This decrease of oxygen tension can be due to a reduced supply in ...

induction-and-testing-of-hypoxia-in-cell-culture

Research

JoVE Journal

Biology

84.5K Aufrufe.  Baylor College of Medicine. Hier schlagen wir einfache Methoden, um eine Hypoxie in Zellkulturen und einfache Tests veranlassen, die hypoxischen Zustand der Kulturen zu bewerten.

Serie: Induction and Testing of Hypoxia in Cell Culture

Culture of Mouse Neural Stem Cell Precursors

Primary neural stem cell cultures are useful for studying the mechanisms underlying central nervous system development. Stem cell research will increase our understanding of the nervous system and may allow us to develop treatments for currently incurable brain diseases and injuries. In addition, stem cells should be used for stem cell research aimed at the detailed study of mechanisms of neural differentiation and transdifferentiation and the genetic and environmental signals that direct the specialization of the cells into particular cell types.  This video demonstrates a technique used to disaggregate cells from the embryonic day 12.5 mouse dorsal forebrain. The dissection procedure includes harvesting E12.5 mouse embryos from the uterus, removing the "skin" with fine dissecting forceps and finally isolating pieces of cerebral cortex. Following the dissection, the tissue is digested and mechanically dissociated. The resuspended dissociated cells are then cultured in "stem cell" media that favors growth of neural stem cells.

This video describes the method used for isolation of neuroprecursors from the developing cortex of embryonic mice. The procedure for removing embryos from the uterus, dissecting the cortical tissue, and digesting the isolated cerebral cortex is shown.

Primary neural stem cell cultures are useful for studying the mechanisms underlying central nervous system development. Stem cell research will increase ...

Induction and Monitoring of Adoptive Delayed-Type Hypersensitivity in Rats

Delayed type hypersensitivity (DTH) is an inflammatory reaction mediated by CCR7- effector memory T lymphocytes that infiltrate the site of injection of an antigen against which the immune system has been primed. The inflammatory reaction is characterized by redness and swelling of the site of antigenic challenge. It is a convenient model to determine the in vivo efficacy of immunosuppressants. Cutaneous DTH can be induced either by adoptive transfer of antigen-specific T lymphocytes or by active immunization with an antigen, and subsequent intradermal challenge with the antigen to induce the inflammatory reaction in a given skin area. DTH responses can be induced to various antigens, for example ovalbumin, tuberculin, tetanus toxoid, or keyhole limpet hemocyanin. Such reactions can also be induced against autoantigen, for example to myelin basic protein (MBP) in rats with experimental autoimmune encephalomyelitis induced with MBP, an animal model for multiple sclerosis (1).
Here we demonstrate how to induce an adoptive DTH reaction in Lewis rats. We will first stimulate ovalbumin-specific T cells in vitro and inject these activated cells intraperitoneally to naive rats. After allowing the cells to equilibrate in vivo for 2 days, we will challenge the rats with ovalbumin in the pinna of one ear, while the other ear wil receive saline. The inflammatory reaction will be visible 3-72 hours later and ear thickness will be measured as an indication of DTH severity.

Delayed type hypersensitivity (DTH) is an inflammatory reaction mediated by CCR7- effector memory T (TEM) lymphocytes. Here we demonstrate how to activate antigen-specific TEM cells, induce adoptive DTH in Lewis rats and monitor the inflammatory response.

Delayed type hypersensitivity (DTH) is an inflammatory reaction mediated by CCR7- effector memory T lymphocytes that infiltrate the site of injection of ...

Efficient Derivation of Human Cardiac Precursors and Cardiomyocytes from Pluripotent Human Embryonic Stem Cells with Small Molecule Induction

To date, the lack of a suitable human cardiac cell source has been the major setback in regenerating the human myocardium, either by cell-based transplantation or by cardiac tissue engineering1-3. Cardiomyocytes become terminally-differentiated soon after birth and lose their ability to proliferate. There is no evidence that stem/progenitor cells derived from other sources, such as the bone marrow or the cord blood, are able to give rise to the contractile heart muscle cells following transplantation into the heart1-3. The need to regenerate or repair the damaged heart muscle has not been met by adult stem cell therapy, either endogenous or via cell delivery1-3. The genetically stable human embryonic stem cells (hESCs) have unlimited expansion ability and unrestricted plasticity, proffering a pluripotent reservoir for in vitro derivation of large supplies of human somatic cells that are restricted to the lineage in need of repair and regeneration4,5. Due to the prevalence of cardiovascular disease worldwide and acute shortage of donor organs, there is intense interest in developing hESC-based therapies as an alternative approach. However, how to channel the wide differentiation potential of pluripotent hESCs efficiently and predictably to a desired phenotype has been a major challenge for both developmental study and clinical translation. Conventional approaches rely on multi-lineage inclination of pluripotent cells through spontaneous germ layer differentiation, resulting in inefficient and uncontrollable lineage-commitment that is often followed by phenotypic heterogeneity and instability, hence, a high risk of tumorigenicity6-8 (see a schematic in Fig. 1A). In addition, undefined foreign/animal biological supplements and/or feeders that have typically been used for the isolation, expansion, and differentiation of hESCs may make direct use of such cell-specialized grafts in patients problematic9-11. To overcome these obstacles, we have resolved the elements of a defined culture system necessary and sufficient for sustaining the epiblast pluripotence of hESCs, serving as a platform for de novo derivation of clinically-suitable hESCs and effectively directing such hESCs uniformly towards clinically-relevant lineages by small molecules12 (see a schematic in Fig. 1B). After screening a variety of small molecules and growth factors, we found that such defined conditions rendered nicotinamide (NAM) sufficient to induce the specification of cardiomesoderm direct from pluripotent hESCs that further progressed to cardioblasts that generated human beating cardiomyocytes with high efficiency (Fig. 2). We defined conditions for induction of cardioblasts direct from pluripotent hESCs without an intervening multi-lineage embryoid body stage, enabling well-controlled efficient derivation of a large supply of human cardiac cells across the spectrum of developmental stages for cell-based therapeutics.

We have established a protocol for induction of cardioblasts direct from pluripotent human embryonic stem cells maintained under defined conditions with small molecules, which enables derivation of a large supply of human cardiac progenitors and functional cardiomyocytes for cardiovascular repair.

To date, the lack of a suitable human cardiac cell source has been the major setback in regenerating the human myocardium, either by cell-based ...

Isolation and Primary Culture of Rat Hepatic Cells

Primary hepatocyte culture is a valuable tool that has been extensively used in basic research of liver function, disease, pathophysiology, pharmacology and other related subjects. The method based on two-step collagenase perfusion for isolation of intact hepatocytes was first introduced by Berry and Friend in 1969 1 and, since then, has undergone many modifications. The most commonly used technique was described by Seglenin 1976 2. Essentially, hepatocytes are dissociated from anesthetized adult rats by a non-recirculating collagenase perfusion through the portal vein. The isolated cells are then filtered through a 100 &mu;m pore size mesh nylon filter, and cultured onto plates. After 4-hour culture, the medium is replaced with serum-containing or serum-free medium, e.g. HepatoZYME-SFM, for additional time to culture. These procedures require surgical and sterile culture steps that can be better demonstrated by video than by text. Here, we document the detailed steps for these procedures by both video and written protocol, which allow consistently in the generation of viable hepatocytes in large numbers.

Primary hepatocytes provide a valuable tool to evaluate biochemical, molecular, and metabolic functions in a physiologically relevant experimental system. We describe a reliable protocol for rat in situ liver perfusion, which consistently generates viable hepatocytes up to 1.0 &times; 108 cells per preparation with cell viability between 88 ~ 96%.

Primary hepatocyte culture is a valuable tool that has been extensively used in basic research of liver function, disease, pathophysiology, pharmacology ...

The Slice Culture Method for Following Development of Tooth Germs In Explant Culture

Explant culture allows manipulation of developing organs at specific time points&#160;and is therefore an important method for the developmental biologist. For many organs it is difficult to access developing tissue to allow monitoring during ex vivo culture. The slice culture method allows access to tissue so that morphogenetic movements can be followed and specific cell populations can be targeted for manipulation or lineage tracing.
In this paper we describe a method of slice culture that has been very successful for culture of tooth germs in a range of species. The method provides excellent access to the tooth germs, which develop at a similar rate to that observed in vivo, surrounded by the other jaw tissues. This allows tissue interactions between the tooth and surrounding tissue to be monitored. Although this paper concentrates on tooth germs, the same protocol can be applied to follow development of a number of other organs, such as salivary glands, Meckel&#39;s cartilage, nasal glands, tongue, and ear.

Here we detail a method to culture tooth germs in mandible slices using a tissue chopper. This method allows unique access to the tooth during development, providing excellent opportunity for manipulation and lineage tracing, not available using more traditional culture methods.

Explant culture allows manipulation of developing organs at specific time points&#160;and is therefore an important method for the developmental ...

Isolation, Culture, and Transplantation of Muscle Satellite Cells

Muscle satellite cells are a stem cell population required for postnatal skeletal muscle development and regeneration, accounting for 2-5% of sublaminal nuclei in muscle fibers. In adult muscle, satellite cells are normally mitotically quiescent. Following injury, however, satellite cells initiate cellular proliferation to produce myoblasts, their progenies, to mediate the regeneration of muscle. Transplantation of satellite cell-derived myoblasts has been widely studied as a possible therapy for several regenerative diseases including muscular dystrophy, heart failure, and urological dysfunction. Myoblast transplantation into dystrophic skeletal muscle, infarcted heart, and dysfunctioning urinary ducts has shown that engrafted myoblasts can differentiate into muscle fibers in the host tissues and display partial functional improvement in these diseases. Therefore, the development of efficient purification methods of quiescent satellite cells from skeletal muscle, as well as the establishment of satellite cell-derived myoblast cultures and transplantation methods for myoblasts, are essential for understanding the molecular mechanisms behind satellite cell self-renewal, activation, and differentiation. Additionally, the development of cell-based therapies for muscular dystrophy and other regenerative diseases are also dependent upon these factors.

However, current prospective purification methods of quiescent satellite cells require the use of expensive fluorescence-activated cell sorting (FACS) machines. Here, we present a new method for the rapid, economical, and reliable purification of quiescent satellite cells from adult mouse skeletal muscle by enzymatic dissociation followed by magnetic-activated cell sorting (MACS). Following isolation of pure quiescent satellite cells, these cells can be cultured to obtain large numbers of myoblasts after several passages. These freshly isolated quiescent satellite cells or ex vivo expanded myoblasts can be transplanted into cardiotoxin (CTX)-induced regenerating mouse skeletal muscle to examine the contribution of donor-derived cells to regenerating muscle fibers, as well as to satellite cell compartments for the examination of self-renewal activities.

The isolation and culture of a pure population of quiescent satellite cells, a muscle stem cell population, is essential to the understanding of muscle stem cell biology and regeneration, as well as stem cell transplantation for therapies in muscular dystrophy and other degenerative diseases.&#160;

Muscle satellite cells are a stem cell population required for postnatal skeletal muscle development and regeneration, accounting for 2-5% of sublaminal ...

Analysis of Global RNA Synthesis at the Single Cell Level following Hypoxia

Hypoxia or lowering of the oxygen availability is involved in many physiological and pathological processes. At the molecular level, cells initiate a particular transcriptional program in order to mount an appropriate and coordinated cellular response. The cell possesses several oxygen sensor enzymes that require molecular oxygen as cofactor for their activity. These range from prolyl-hydroxylases to histone demethylases. The majority of studies analyzing cellular responses to hypoxia are based on cellular populations and average studies, and as such single cell analysis of hypoxic cells are seldom performed. Here we describe a method of analysis of global RNA synthesis at the single cell level in hypoxia by using Click-iT RNA imaging kits in an oxygen controlled workstation, followed by microscopy analysis and quantification.&nbsp; Using cancer cells exposed to hypoxia for different lengths of time, RNA is labeled and measured in each cell. This analysis allows the visualization of temporal and cell-to-cell changes in global RNA synthesis following hypoxic stress.

We describe a technique for analysis of global RNA synthesis in hypoxia using imaging. Click-chemistry labeling of RNA has not previously been performed under hypoxia and allows visualization of global RNA changes at the single cell level. This approach complements the existing averaged RNA techniques, allowing direct visualization of cell-to-cell changes in global RNA synthesis.

Hypoxia or lowering of the oxygen availability is involved in many physiological and pathological processes. At the molecular level, cells initiate a ...

The c-FOS Protein Immunohistological Detection: A Useful Tool As a Marker of Central Pathways Involved in Specific Physiological Responses In Vivo and Ex Vivo

Many studies seek to identify and map the brain regions involved in specific physiological regulations. The proto-oncogene c-fos, an immediate early gene, is expressed in neurons in response to various stimuli. The protein product can be readily detected with immunohistochemical techniques leading to the use of c-FOS detection to map groups of neurons that display changes in their activity. In this article, we focused on the identification of brainstem neuronal populations involved in the ventilatory adaptation to hypoxia or hypercapnia. Two approaches were described to identify involved neuronal populations in vivo in animals and ex vivo in deafferented brainstem preparations. In vivo, animals were exposed to hypercapnic or hypoxic gas mixtures. Ex vivo, deafferented preparations were superfused with hypoxic or hypercapnic artificial cerebrospinal fluid. In both cases, either control in vivo animals or ex vivo preparations were maintained under normoxic and normocapnic conditions. The comparison of these two approaches allows the determination of the origin of the neuronal activation i.e., peripheral and/or central. In vivo and ex vivo, brainstems were collected, fixed, and sliced into sections. Once sections were prepared, immunohistochemical detection of the c-FOS protein was made in order to identify the brainstem groups of cells activated by hypoxic or hypercapnic stimulations. Labeled cells were counted in brainstem respiratory structures. In comparison to the control condition, hypoxia or hypercapnia increased the number of c-FOS labeled cells in several specific brainstem sites that are thus constitutive of the neuronal pathways involved in the adaptation of the central respiratory drive.

The c-FOS Protein Immunohistological Detection: A Useful Tool As a Marker of Central Pathways Involved in Specific Physiological Responses In Vivo and Ex Vivo

Here, we present a protocol based on c-FOS protein immunohistological detection, a classical technique used for the identification of neuronal populations involved in specific physiological responses in vivo and ex vivo.

Many studies seek to identify and map the brain regions involved in specific physiological regulations. The proto-oncogene c-fos, an immediate early gene, ...

Detection of RNA-binding Proteins by In Vitro RNA Pull-down in Adipocyte Culture

RNA-binding proteins (RBPs) are emerging as a regulatory layer in the development and function of adipose. RBPs play a key role in the gene expression regulation at posttranscriptional levels by affecting the stability and translational efficiency of target mRNAs. RNA pull-down technique has been widely used to study RNA-protein interaction, which is necessary to elucidate the mechanism underlying RBPs&#39; as well as long non-coding RNAs&#39; (lncRNAs) function. However, the high lipid abundance in adipocytes poses a technical challenge in conducting this experiment. Here a detailed RNA pull-down protocol is optimized for primary adipocyte culture. An RNA fragment from androgen receptor&#39;s (AR) 3&#39; untranslated region (3&#39;UTR) containing an adenylate-uridylate-rich elementwas used as an example to demonstrate how to retrieve its RBP partner, HuR protein, from adipocyte lystate. The method described here can be applied to detect the interactions between RBPs and noncoding RNAs, as well as between RBPs and coding RNAs.

Detection of RNA-binding Proteins by In Vitro RNA Pull-down in Adipocyte Culture

An RNA pull-down protocol is optimized here for detection of interactions between RNA-binding proteins (RBPs) and noncoding as well as coding RNAs. An RNA fragment from androgen receptor (AR) was used as an example to demonstrate how to retrieve its RBP from lystate of primary brown adipocytes.

RNA-binding proteins (RBPs) are emerging as a regulatory layer in the development and function of adipose. RBPs play a key role in the gene expression ...

Optimized Scratch Assay for In Vitro Testing of Cell Migration with an Automated Optical Camera

Cell migration is an important process that influences many aspects of health, such as wound healing and cancer, and it is, therefore, crucial for developing methods to study the migration. The scratch assay has long been the most common in vitro method to test compounds with anti- and pro-migration properties because of its low cost and simple procedure. However, an often-reported problem of the assay is the accumulation of cells across the edge of the scratch. Furthermore, to obtain data from the assay, images of different exposures must be taken over a period of time at the exact same spot to compare the movements of the migration. Different analysis programs can be used to describe the scratch closure, but they are labor intensive, inaccurate, and forces cycles of temperature changes. In this study, we demonstrate an optimized method for testing the migration effect, e.g. with the naturally occurring proteins Human- and Bovine-Lactoferrin and their N-terminal peptide Lactoferricin on the epithelial cell line HaCaT. A crucial optimization is to wash and scratch in PBS, which eliminates the aforementioned accumulation of cells along the edge. This could be explained by the removal of cations, which have been shown to have an effect on keratinocyte cell-cell connection. To ensure true detection of migration, pre-treating with mitomycin C, a DNA synthesis inhibitor, was added to the protocol. Finally, we demonstrate the automated optical camera, which eliminates excessive temperature cycles, manual labor with scratch closure analysis, while improving on reproducibility and ensuring analysis of identical sections of the scratch over time.

Optimized Scratch Assay for In Vitro Testing of Cell Migration with an Automated Optical Camera

Here we describe a procedure to test the cell migration in vitro with an automated optical camera microscope. The scratch assay has been widely used where the closure of the scratch is followed for a set period. The optical microscope enables dependable and cheap detection of cell migration.