Name: a simple pit assay protocol to visualize and quantify osteoclastic resorption in vitro
Uploaded: 2022-06-16T13:40:00
Description: Watch this Scientific Journal Video about A Simple Pit Assay Protocol to Visualize and Quantify Osteoclastic Resorption In Vitro at JoVE.com

This work was partially funded by the China Scholarship Council [CSC No. 201808440394]. W.C. was financed by CSC.

The protocol was reviewed and approved by the local ethics committee (approval number 287/2020B02).
1. Preparation of calcium phosphate coated cell culture plates
<ol>
	<li>Preparation of calcium stock solution (25 mM CaCl2&#183;2H2O, 1.37 M NaCl, 15 mM MgCl2&#183;6H2O in Tris buffer)
	<ol>
		<li>Prepare 50 mM Tris buffer and adjust pH to 7.4 using 1 M HCl.</li>
		<li>Set up a glass beaker on a magnetic stirrer and add 100 mL of 50...

<ol>
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H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Osteoblast-osteoclast+communication+and+bone+homeostasis.">Osteoblast-osteoclast communication and bone homeostasis.</a> Cells. 9 (9), (2020).</li><li>Teitelbaum, S. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bone+resorption+by+osteoclasts.">Bone resorption by osteoclasts.</a> Science. 289 (5484), 1504-1508 (2000).</li><li>Boyle, W. J., Simonet, W. S., Lacey, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Osteoclast+differentiation+and+activation.">Osteoclast differentiation and activation.</a> Nature. 423 (6937), 337-342 (2003).</li><li>Baron, R., Neff, L., Louvard, D., Courtoy, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell-mediated+extracellular+acidification+and+bone+resorption:+evidence+for+a+low+pH+in+resorbing+lacunae+and+localization+of+a+100-kD+lysosomal+membrane+protein+at+the+osteoclast+ruffled+border.">Cell-mediated extracellular acidification and bone resorption: evidence for a low pH in resorbing lacunae and localization of a 100-kD lysosomal membrane protein at the osteoclast ruffled border.</a> Journal of Cell Biology. 101 (6), 2210-2222 (1985).</li><li>Blair, H. C., Teitelbaum, S. L., Ghiselli, R., Gluck, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Osteoclastic+bone+resorption+by+a+polarized+vacuolar+proton+pump.">Osteoclastic bone resorption by a polarized vacuolar proton pump.</a> Science. 245 (4920), 855-857 (1989).</li><li>Zhu, L., 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=Osteoclast-mediated+bone+resorption+is+controlled+by+a+compensatory+network+of+secreted+and+membrane-tethered+metalloproteinases.">Osteoclast-mediated bone resorption is controlled by a compensatory network of secreted and membrane-tethered metalloproteinases.</a> Science Translational Medicine. 12 (529), 6143 (2020).</li><li>Gowen, M., 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=Cathepsin+K+knockout+mice+develop+osteopetrosis+due+to+a+deficit+in+matrix+degradation+but+not+demineralization.">Cathepsin K knockout mice develop osteopetrosis due to a deficit in matrix degradation but not demineralization.</a> The Journal of Bone and Mineral Research. 14 (10), 1654-1663 (1999).</li><li>Abu-Amer, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=IL-4+abrogates+osteoclastogenesis+through+STAT6-dependent+inhibition+of+NF-kappaB.">IL-4 abrogates osteoclastogenesis through STAT6-dependent inhibition of NF-kappaB.</a> Journal of Clinical Investigation. 107 (11), 1375-1385 (2001).</li><li>Patntirapong, S., Habibovic, P., Hauschka, P. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+soluble+cobalt+and+cobalt+incorporated+into+calcium+phosphate+layers+on+osteoclast+differentiation+and+activation.">Effects of soluble cobalt and cobalt incorporated into calcium phosphate layers on osteoclast differentiation and activation.</a> Biomaterials. 30 (4), 548-555 (2009).</li><li>Sorensen, M. G., 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=Characterization+of+osteoclasts+derived+from+CD14++monocytes+isolated+from+peripheral+blood.">Characterization of osteoclasts derived from CD14+ monocytes isolated from peripheral blood.</a> The Journal of Bone and Mineral Metabolism. 25 (1), 36-45 (2007).</li><li>Kumar, A., 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=Synergistic+effect+of+biphasic+calcium+phosphate+and+platelet-rich+fibrin+attenuate+markers+for+inflammation+and+osteoclast+differentiation+by+suppressing+NF-kappaB/MAPK+signaling+pathway+in+chronic+periodontitis.">Synergistic effect of biphasic calcium phosphate and platelet-rich fibrin attenuate markers for inflammation and osteoclast differentiation by suppressing NF-kappaB/MAPK signaling pathway in chronic periodontitis.</a> Molecules. 26 (21), 6578 (2021).</li><li>Henriksen, K., Karsdal, M. A., Taylor, A., Tosh, D., Coxon, F. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Generation+of+human+osteoclasts+from+peripheral+blood.">Generation of human osteoclasts from peripheral blood.</a> Methods in Molecular Biology. 816, 159-175 (2012).</li><li>Maria, S. M., 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=Reproducible+quantification+of+osteoclastic+activity:+characterization+of+a+biomimetic+calcium+phosphate+assay.">Reproducible quantification of osteoclastic activity: characterization of a biomimetic calcium phosphate assay.</a> Journal of Biomedical Materials Research Part B: Applied Biomaterials. 102 (5), 903-912 (2014).</li><li>Kong, L., Smith, W., Hao, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Overview+of+RAW264.7+for+osteoclastogensis+study:+Phenotype+and+stimuli.">Overview of RAW264.7 for osteoclastogensis study: Phenotype and stimuli.</a> Journal of Cellular and Molecular Medicine. 23 (5), 3077-3087 (2019).</li><li>Li, P., 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=Systemic+tumor+necrosis+factor+alpha+mediates+an+increase+in+peripheral+CD11bhigh+osteoclast+precursors+in+tumor+necrosis+factor+alpha-transgenic+mice.">Systemic tumor necrosis factor alpha mediates an increase in peripheral CD11bhigh osteoclast precursors in tumor necrosis factor alpha-transgenic mice.</a> Arthritis &amp; Rheumatology. 50 (1), 265-276 (2004).</li><li>Arai, F., 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=Commitment+and+differentiation+of+osteoclast+precursor+cells+by+the+sequential+expression+of+c-Fms+and+receptor+activator+of+nuclear+factor+kappaB+(RANK)+receptors.">Commitment and differentiation of osteoclast precursor cells by the sequential expression of c-Fms and receptor activator of nuclear factor kappaB (RANK) receptors.</a> Journal of Experimental Medicine. 190 (12), 1741-1754 (1999).</li><li>Xing, L., 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=NF-kappaB+p50+and+p52+expression+is+not+required+for+RANK-expressing+osteoclast+progenitor+formation+but+is+essential+for+RANK-+and+cytokine-mediated+osteoclastogenesis.">NF-kappaB p50 and p52 expression is not required for RANK-expressing osteoclast progenitor formation but is essential for RANK- and cytokine-mediated osteoclastogenesis.</a> The Journal of Bone and Mineral Research. 17 (7), 1200-1210 (2002).</li><li>Miyamoto, T., 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=Bifurcation+of+osteoclasts+and+dendritic+cells+from+common+progenitors.">Bifurcation of osteoclasts and dendritic cells from common progenitors.</a> Blood. 98 (8), 2544-2554 (2001).</li></ol>

Here we describe a simple and reliable method for an osteoclastic resorption assay using OCs derived and expanded in vitro from PBMCs. The used CaP coated cell culture plates can be easily prepared and visualized using lab-available materials. In addition to unsorted PBMCs adopted in this protocol, OCs generated from murine monocytic cells21 and bone marrow macrophage cells17 have also been cultured on similar synthetic substrates for pit assay, thus these cell sou...

<a href="https://app.jove.com/t/6601">This corrects</a> the article <a href="https://dx.doi.org/10.3791/64016">10.3791/64016</a>

An erratum was issued for:&#160;<a href="https://www.jove.com/t/64016">A Simple Pit Assay Protocol to Visualize and Quantify Osteoclastic Resorption In Vitro</a>. The Protocol section was&#160;updated.

Erratum: A Simple Pit Assay Protocol to Visualize and Quantify Osteoclastic Resorption In Vitro

Osteoclasts (OCs) are tissue-specific macrophages derived from hematopoietic stem cells (HSCs), playing a pivotal role in bone remodeling together with osteoblasts1. Sex hormone-induced, immunological, and malignant bone disorders that destroy bone systemically or locally are due to excess osteoclastic activity, including menopause-related osteoporosis2, rheumatoid arthritis3, periodontal disease4, myeloma bone disease5, and osteolytic bone metastasis6. In contrast, defects in OC formation and function can also cause osteopetrosis7. HSCs undergo differentiation into OC progenitors under macrophage colony-stimulating factor (M-CSF, gene symbol ACP5) stimulation. In the presence of both M-CSF and receptor activator of NF-&#954;B ligand (RANKL, gene symbol TNFSF11), OC progenitors differentiate further into mononuclear OCs and subsequently fuse to become multinucleated OCs8,9,10. Both cytokines M-CSF and RANKL are indispensable and sufficient for induction of osteoclastic markers such as calcitonin receptor (CT), receptor activator of nuclear factor &#954; B (RANK), proton pump V-ATPase, chloride channel 7 alpha subunit (CIC-7), integrin &#946;3, tartrate-resistant acid phosphatase (TRAP, gene symbol ACP5), lysosomal cysteine protease cathepsin K (CTSK), and matrix metallopeptidase 9 (MMP9). Activated OCs form a sealing zone on the bone surface through the formation of an actin ring with a ruffled border11,12. Within the sealing zone, OCs mediate resorption through secreting protons via the proton pump V-ATPase12,13, MMP914, and CTSK15, leading to the formation of lacunae.
For in vitro experiments, OC progenitors can be obtained by expansion of bone marrow macrophages from mice&#39;s femur and tibia16,17, as well as by isolation of human peripheral blood mononuclear cells (PBMCs) from blood samples and buffy coats18,19,20, or by differentiation of the immortalized murine monocytic cells RAW 264.721,22.
In the present protocol, we describe an osteoclastic resorption assay in CaP coated cell culture plates using OCs derived from primary PBMCs. The CaP coated cell culture plates method used here are adopted and refined from the method described previously by Patntirapong et al.17 and Maria et al.21. To obtain OC precursors, PBMCs are isolated by density gradient centrifugation and expanded as described previously20.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>AgNO3</td>
			<td>SERVA Electrophoresis GmbH</td>
			<td>35110</td>
			<td>Silver nitrate</td>
		</tr>
		<tr>
			<td>a-MEM</td>
			<td>Gibco</td>
			<td>32561-029</td>
			<td>MEM alpha, GlutaMAX, no nucleosides</td>
		</tr>
		<tr>
			<td>amphotericin B</td>
			<td>Biochrom</td>
			<td>03-028-1B</td>
			<td>Amphotericin B Solution</td>
		</tr>
		<tr>
			<td>CaCl2</td>
			<td>Sigma-Aldrich</td>
			<td>21097-50G</td>
			<td>Calcium chloride Dihydrate</td>
		</tr>
		<tr>
			<td>Calcein</td>
			<td>Sigma-Aldrich</td>
			<td>C0875</td>
			<td>Calcein</td>
		</tr>
		<tr>
			<td>FBS</td>
			<td>Sigma-Aldrich</td>
			<td>F7524</td>
			<td>fetal bovine serum</td>
		</tr>
		<tr>
			<td>Ficoll</td>
			<td>Cytiva</td>
			<td>17144002</td>
			<td>Ficoll Paque Plus</td>
		</tr>
		<tr>
			<td>Fixation buffer</td>
			<td>Biolegend</td>
			<td>420801</td>
			<td>Paraformaldehyde</td>
		</tr>
		<tr>
			<td>HCl</td>
			<td>Merk</td>
			<td>1.09057.1000</td>
			<td>Hydrochloric acid</td>
		</tr>
		<tr>
			<td>Hoechst 33342</td>
			<td>Promokine</td>
			<td>PK-CA707-40046</td>
			<td>Hoechst 33342</td>
		</tr>
		<tr>
			<td>M-CSF</td>
			<td>PeproTech</td>
			<td>300-25</td>
			<td>Recombinant Human M-CSF</td>
		</tr>
		<tr>
			<td>MgCl2</td>
			<td>Sigma-Aldrich</td>
			<td>7791-18-6</td>
			<td>Magnesium chloride</td>
		</tr>
		<tr>
			<td>Na2HPO4</td>
			<td>AppliChem GmbH</td>
			<td>A2943,0250</td>
			<td>di- Sodium hydrogen phosphate anhydrous</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Merk</td>
			<td>S7653-250G</td>
			<td>Sodium chloride</td>
		</tr>
		<tr>
			<td>NaHCO3</td>
			<td>Merk</td>
			<td>K15322429</td>
			<td>Bicarbonate of Soda</td>
		</tr>
		<tr>
			<td>PBS</td>
			<td>Lonza</td>
			<td>17-512F</td>
			<td>Dulbecco&#39;s Phosphate Buffered Saline (1X), DBPS without Calcium and Magnesium</td>
		</tr>
		<tr>
			<td>Pen-Strep</td>
			<td>Lonza</td>
			<td>DE17-602E</td>
			<td>Penicillin-Streptomycin Mixture</td>
		</tr>
		<tr>
			<td>Phalloidin-Alexa Fluor 546</td>
			<td>Invitrogen</td>
			<td>A22283</td>
			<td>Alexa Fluor 546 Phalloidin</td>
		</tr>
		<tr>
			<td>RANKL</td>
			<td>PeproTech</td>
			<td>310-01</td>
			<td>Recombinant Human sRANK Ligand (E.coli derived)</td>
		</tr>
		<tr>
			<td>Tris</td>
			<td>Sigma-Aldrich</td>
			<td>93362</td>
			<td>Tris(hydroxymethyl)aminomethan</td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>Sigma-Aldrich</td>
			<td>T8787</td>
			<td>Alkyl Phenyl Polyethylene Glycol</td>
		</tr>
		<tr>
			<td>TrypLE Express</td>
			<td>Gibco</td>
			<td>12605010</td>
			<td>Recombinant cell-dissociation enzymes</td>
		</tr>
	</tbody>
</table>

a simple pit assay protocol to visualize and quantify osteoclastic resorption in vitro

Mature osteoclasts are multinucleated cells that can degrade bone through the secretion of acids and enzymes. They play a crucial role in various diseases (e.g., osteoporosis and bone cancer) and are therefore important objects of research. In vitro, their activity can be analyzed by the formation of resorption pits. In this protocol, we describe a simple pit assay method using calcium phosphate (CaP) coated cell culture plates, which can be easily visualized and quantified. Osteoclast precursors derived from human peripheral blood mononuclear cells (PBMCs) were cultured on the coated plates in the presence of osteoclastogenic stimuli. After 9 days of incubation, osteoclasts were fixed and stained for fluorescence imaging while the CaP coating was counterstained by calcein. To quantify the resorbed area, the CaP coating on plates was stained with 5% AgNO3 and visualized by brightfield imaging. The resorption pit area was quantified using ImageJ.

The calcium phosphate coating on the bottom of cell culture plates was performed in two coating steps comprising a 3-day pre-calcification and a 1-day calcification step. As shown in Figure 1, uniformly distributed calcium phosphate was obtained on the bottom of the 96-well plates. The coating adhered very well to the bottom after the performed washing steps.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/6401...

Watch this Scientific Journal Video about A Simple Pit Assay Protocol to Visualize and Quantify Osteoclastic Resorption In Vitro at JoVE.com

A Simple Pit Assay Protocol to Visualize and Quantify Osteoclastic Resorption In Vitro

Here, we present a simple and effective assay procedure for resorption pit assays using calcium phosphate coated cell culture plates.

A Simple Pit Assay Protocol to Visualize and Quantify Osteoclastic Resorption In Vitro

Mature osteoclasts are multinucleated cells that can degrade bone through the secretion of acids and enzymes. They play a crucial role in various diseases ...

Our protocol describes a simple and reliable method for an osteoclastic resorption assay. The use of calcium phosphate coated cell culture plates can be easily prepared and visualized using lab available materials. In contrast to opaque bone or dentin slices, the calcium phosphate coating allows visualization of resorption pits and cells at the same time.In this protocol, we use PBMCs for osteoclast differentiation. However, it can also be applied to other cell types like bone marrow derived monocytes or Raw 264.7 cells. First take a flat bottom 96 well cell culture plate and pipette 300 microliters of previously prepared calcium phosphate solution into each well.Then, cover the plate with the lid and incubate the plate at 37 degrees Celsius for three days. After three days, aspirate the pre-calcification solution from the pre-calcified 96 well cell culture plates and add 300 microliters of calcium phosphate solution to each well. Cover the plates with a lid and incubate at 37 degrees Celsius for one day.Then invert the plate to pour out the solution and thoroughly wash the plate thrice with deionized water. Immediately dry the plate using a hair dryer or compressed carbon dioxide or nitrogen gas to maintain a uniform surface. Now, irradiate the coated plate on a clean bench with ultraviolet rays for one hour.Use the coated plate immediately or seal the plate with Parafilm and store it at room temperature. Dilute 15 milliliters of fresh blood with an equal volume of PBS and mix them by inverting or pipetting several times. Then take 15 milliliters of density gradient solution in a 50 milliliter conical tube, tilt the tube, and carefully layer 30 milliliters of diluted blood sample on the 15 milliliters of density gradient solution.Later, centrifuge the tube in a swinging bucket rotor without break at 810 times G for 20 minutes at 20 degrees Celsius. Then aspirate the upper layer leaving the mononuclear cell layer undisturbed at the interface. Carefully transfer the mononuclear cell layer to a new 50 milliliter conical tube.Fill the tube with PBS, mix, and centrifuge at 300 times G for 10 minutes at 20 degrees Celsius. Re-suspend PBMCs in a complete alpha-MEM containing 20 nanograms per milliliters macrophage colony stimulating factor, and seed 2.5 times 10 to the fifth cells per centimeter square PBMCs in a flask. Incubate the calcium phosphate coated plates with 50 microliters of fetal bovine serum at 37 degrees Celsius for one hour.Next, wash the flask twice with PBS to detach the osteoclast precursors from dead or non-adherent cells, then add four milliliters of trypsin per 75 square centimeter flask. After 30 minutes, stop the digestion by adding four milliliters of complete alpha-MEM, then carefully detach the cells using a cell scraper. Transfer the cells into a 50 milliliter tube and count the total number of cells using a counting chamber.Centrifuge the tube at 350 times G for seven minutes to pellet the cells and resusspend the pellet and complete alpha MEM containing M-CSF and RANKL to get one times 10 to the six cells per milliliter. Aspirate the fetal bovine serum from the calcium phosphate coated plate, and pipette 200 microliters of cell suspension per well. After the incubation, wash the cells twice with PBS.Fix the cells with 4%paraformaldehyde for 10 minutes and wash again with PBS. For staining, add permeabilization buffer to the fixed cells and incubate them for five minutes. To stain the actin filaments, incubate the cells with 100 microliters of Alexa Fluor 546 labeled phalloidin solution in PBS for 30 minutes, then aspirate the staining solution and stain the nuclei using 100 microliters of Hoechst for 10 minutes.Stain calcium phosphate coating with 100 microliters of 10 micromolar calcein and PBS for 10 minutes. After washing thrice with PBS, capture images. For Von Kossa staining of calcium phosphate coating add 50 microliters of 5%silver nitrate and deionized water to each well, and incubate the plate under ultraviolet radiation for one hour until the coating on the bottom of the wells has turned brown.The calcium phosphate coating at the bottom of the 96 well plates appeared to be uniform and well adhered. After nine days of culture in M-CSF and RANKL on the calcium phosphate coated plates, osteoclast precursors formed resorption pits and large osteoclasts. The multi-nucleated osteoclasts located in the pits expressed high TRAP levels.The mature osteoclasts showed the presence of three or more nuclei and the distinct actin ring. The green calcium phosphate coating showed the presence of black resorption pits. The pit area fluorescence images was measured using the thresholding tool of image J.The number and size of osteoclasts were calculated using ROI manager and the polygon selection tool of image J.Osteoclasts'precursors grown in the absence of RANKL could not form resorption pits, however M-CSF and RANKL facilitated the formation of osteoclastogenic pits.And the pit area was quantified using image J.Immediately drying the coated plate with airflow helps to make a uniform calcium phosphate coating. Otherwise it's prone to form a thicker coating in the middle of the well.

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Medicine

Corneal Confocal Microscopy: A Novel Non-invasive Technique to Quantify Small Fibre Pathology in Peripheral Neuropathies

The accurate quantification of peripheral neuropathy is important to define at risk patients, anticipate deterioration, and assess new therapies. Conventional methods assess neurological deficits and electrophysiology and quantitative sensory testing quantifies functional alterations to detect neuropathy. However, the earliest damage appears to be to the small fibres and yet these tests primarily assess large fibre dysfunction and have a limited ability to demonstrate regeneration and repair. The only techniques which allow a direct examination of unmyelinated nerve fibre damage and repair are sural nerve biopsy with electron microscopy and skin-punch biopsy. However, both are invasive procedures and require lengthy laboratory procedures and considerable expertise. Corneal Confocal microscopy is a non-invasive clinical technique which provides in-vivo imaging of corneal nerve fibres. We have demonstrated early nerve damage, which precedes loss of intraepidermal nerve fibres in skin biopsies together with stratification of neuropathic severity and repair following pancreas transplantation in diabetic patients. We have also demonstrated nerve damage in idiopathic small fibre neuropathy and Fabry's disease.

Corneal Confocal microscopy is a non-invasive clinical technique which may be used to quantify C fibre damage to diagnose and stratify patients with increasing neuropathic severity.

The accurate quantification of peripheral neuropathy is important to define at risk patients, anticipate deterioration, and assess new therapies. ...

Accurate and Simple Measurement of the Pro-inflammatory Cytokine IL-1&beta; using a Whole Blood Stimulation Assay

Inflammatory processes resulting from the secretion of soluble mediators by immune cells, lead to various manifestations in skin, joints and other tissues as well as altered cytokine homeostasis. The innate immune system plays a crucial role in recognizing pathogens and other endogenous danger stimuli. One of the major cytokines released by innate immune cells is Interleukin (IL)-1. Therefore, we utilize a whole blood stimulation assay in order to measure the secretion of inflammatory cytokines and specifically of the pro-inflammatory cytokine IL-1&beta; 1, 2, 3.
Patients with genetic dysfunctions of the innate immune system causing autoinflammatory syndromes show an exaggerated release of mature IL-1&beta; upon stimulation with LPS alone. In order to evaluate the innate immune component of patients who present with inflammatory-associated pathologies, we use a specific immunoassay to detect cellular immune responses to pathogen-associated molecular patterns (PAMPs), such as the gram-negative bacterial endotoxin, lipopolysaccharide (LPS). These PAMPs are recognized by pathogen recognition receptors (PRRs), which are found on the cells of the innate immune system 4, 5, 6, 7. A primary signal, LPS, in conjunction with a secondary signal, ATP, is necessary for the activation of the inflammasome, a multiprotein complex that processes pro-IL-1&beta; to its mature, bioactive form 4, 5, 6, 8, 9, 10.
The whole blood assay requires minimal sample manipulation to assess cytokine production when compared to other methods that require labor intensive isolation and culturing of specific cell populations. This method differs from other whole blood stimulation assays; rather than diluting samples with a ratio of RPMI media, we perform a white blood cell count directly from diluted whole blood and therefore, stimulate a known number of white blood cells in culture 2. The results of this particular whole blood assay demonstrate a novel technique useful in elucidating patient cohorts presenting with autoinflammatory pathophysiologies.

Accurate and Simple Measurement of the Pro-inflammatory Cytokine IL-1&#946; using a Whole Blood Stimulation Assay

We describe a simple immunoassay to measure the production of pro-inflammatory cytokines, such as IL-1 beta production, in patients presenting with autoinflammatory phenotypes. By activating cells in whole blood cultures with pathogen-associated molecular patterns, specifically with lipopolysaccharide, cytokine secretion can be conveniently evaluated in whole blood supernatants.

Inflammatory processes resulting from the secretion of soluble mediators by immune cells, lead to various manifestations in skin, joints and other tissues ...

In vitro Mesothelial Clearance Assay that Models the Early Steps of Ovarian Cancer Metastasis

Ovarian cancer is the fifth leading cause of cancer related deaths in the United States1. Despite a positive initial response to therapies, 70 to 90 percent of women with ovarian cancer develop new metastases, and the recurrence is often fatal2. It is, therefore, necessary to understand how secondary metastases arise in order to develop better treatments for intermediate and late stage ovarian cancer. Ovarian cancer metastasis occurs when malignant cells detach from the primary tumor site and disseminate throughout the peritoneal cavity. The disseminated cells can form multicellular clusters, or spheroids, that will either remain unattached, or implant onto organs within the peritoneal cavity3 (Figure 1, Movie 1). 
All of the organs within the peritoneal cavity are lined with a single, continuous, layer of mesothelial cells4-6 (Figure 2). However, mesothelial cells are absent from underneath peritoneal tumor masses, as revealed by electron micrograph studies of excised human tumor tissue sections3,5-7 (Figure 2). This suggests that mesothelial cells are excluded from underneath the tumor mass by an unknown process. 
Previous in vitro experiments demonstrated that primary ovarian cancer cells attach more efficiently to extracellular matrix than to mesothelial cells8, and more recent studies showed that primary peritoneal mesothelial cells actually provide a barrier to ovarian cancer cell adhesion and invasion (as compared to adhesion and invasion on substrates that were not covered with mesothelial cells)9,10. This would suggest that mesothelial cells act as a barrier against ovarian cancer metastasis. The cellular and molecular mechanisms by which ovarian cancer cells breach this barrier, and exclude the mesothelium have, until recently, remained unknown. 
Here we describe the methodology for an in vitro assay that models the interaction between ovarian cancer cell spheroids and mesothelial cells in vivo (Figure 3, Movie 2). Our protocol was adapted from previously described methods for analyzing ovarian tumor cell interactions with mesothelial monolayers8-16, and was first described in a report showing that ovarian tumor cells utilize an integrin &#x2013;dependent activation of myosin and traction force to promote the exclusion of the mesothelial cells from under a tumor spheroid17. This model takes advantage of time-lapse fluorescence microscopy to monitor the two cell populations in real time, providing spatial and temporal information on the interaction. The ovarian cancer cells express red fluorescent protein (RFP) while the mesothelial cells express green fluorescent protein (GFP). RFP-expressing ovarian cancer cell spheroids attach to the GFP-expressing mesothelial monolayer. The spheroids spread, invade, and force the mesothelial cells aside creating a hole in the monolayer. This hole is visualized as the negative space (black) in the GFP image. The area of the hole can then be measured to quantitatively analyze differences in clearance activity between control and experimental populations of ovarian cancer and/ or mesothelial cells. This assay requires only a small number of ovarian cancer cells (100 cells per spheroid X 20-30 spheroids per condition), so it is feasible to perform this assay using precious primary tumor cell samples. Furthermore, this assay can be easily adapted for high throughput screening.

In vitro Mesothelial Clearance Assay that Models the Early Steps of Ovarian Cancer Metastasis

The mesothelial clearance assay described here takes advantage of fluorescently labeled cells and time-lapse video microscopy to visualize and quantitatively measure the interactions of ovarian cancer multicellular spheroids and mesothelial cell monolayers. This assay models the early steps of ovarian cancer metastasis.

Ovarian cancer is the fifth leading cause of cancer related deaths in the United States1. Despite a positive initial response to therapies, 70 to 90 ...

A Simple Method of Mouse Lung Intubation

A simple procedure to intubate mice for pulmonary function measurements would have several advantages in longitudinal studies with limited numbers or expensive animal. One of the reasons that this is not done more routinely is that it is relatively difficult, despite there being several published studies that describe ways to achieve it. In this paper we demonstrate a procedure that eliminates one of the major hurdles associated with this intubation, that of visualizing the trachea during the entire time of intubation. The approach uses a 0.5 mm fiberoptic light source that serves as an introducer to direct the intubation cannula into the mouse trachea. We show that it is possible to use this procedure to measure lung mechanics in individual mice over a time course of at least several weeks. The technique can be set up with relatively little expense and expertise, and it can be routinely accomplished with relatively little training. This should make it possible for any laboratory to routinely carry out this intubation, thereby allowing longitudinal studies in individual mice, thereby minimizing the number of mice needed and increasing the statistical power by using each mouse as its own control.

This paper describes a striaghforward and efficient method of intubating mice for pulmonary function measurements or pulmonary instillation, that allows the mice to recover and be studied at later times. The procedure involves an inexpensive fiberoptic light source that directly illuminates the trachea.

A  simple procedure to intubate mice for pulmonary function measurements would  have several advantages in longitudinal studies with limited numbers or  ...

A Sensitive Method to Quantify Senescent Cancer Cells

Human cells do not indefinitely proliferate. Upon external and/or intrinsic cues, cells might die or enter a stable cell cycle arrest called senescence. Several cellular mechanisms, such as telomere shortening and abnormal expression of mitogenic oncogenes, have been shown to cause senescence. Senescence is not restricted to normal cells; cancer cells have also been reported to senesce.
	Chemotherapeutical drugs have been shown to induce senescence in cancer cells. However, it remains controversial whether senescence prevents or promotes tumorigenesis. As it might eventually be patient-specific, a rapid and sensitive method to assess senescence in cancer cell will soon be required.
	To this end, the standard &beta;-galactosidase assay, the currently used method, presents major drawbacks: it is time consuming and not sensitive. We propose here a flow cytometry-based assay to study senescence on live cells. This assay offers the advantage of being rapid, sensitive, and can be coupled to the immunolabeling of various cellular markers.

Whether senescence prevents or promotes tumorigenesis remains controversial. Since chemotherapeutical drugs can induce cancer cells to senesce, studying senescence is essential for proposing new therapies. However, the standard and broadly used &beta;-galactosidase assay presents major drawbacks. We propose here a rapid and sensitive flow cytometry-based assay to quantify senescence.

Human cells do not indefinitely proliferate. Upon external and/or intrinsic  cues, cells might die or enter a stable cell cycle arrest called senescence. ...

Cell-based Assay Protocol for the Prognostic Prediction of Idiopathic Scoliosis Using Cellular Dielectric Spectroscopy

This protocol details the experimental and analytical procedure for a cell-based assay developed in our laboratory as a functional test to predict the prognosis of idiopathic scoliosis in asymptomatic and affected children. The assay consists of the evaluation of the functional status of Gi and Gs proteins in peripheral blood mononuclear cells (PBMCs) by cellular dielectric spectroscopy (CDS), using an automated CDS-based instrument, and the classification of children into three functional groups (FG1, FG2, FG3) with respect to the profile of imbalance between the degree of response to Gi and Gs proteins stimulation. The classification is further confirmed by the differential effect of osteopontin (OPN) on response to Gi stimulation among groups and the severe progression of disease is referenced by FG2. Approximately, a volume of 10 ml of blood is required to extract PBMCs by Ficoll-gradient and cells are then stored in liquid nitrogen. The adequate number of PBMCs to perform the assay is obtained after two days of cell culture. Essentially, cells are first incubated with phytohemmaglutinin (PHA). After 24 hr incubation, medium is replaced by a PHA-free culture medium for an additional 24 hr prior to cell seeding and OPN treatment. Cells are then spectroscopically screened for their responses to somatostatin and isoproterenol, which respectively activate Gi and Gs proteins through their cognate receptors. Both somatostatin and isoproterenol are simultaneously injected with an integrated fluidics system and the cells&#39; responses are monitored for 15 min. The assay can be performed with fresh or frozen PBMCs and the procedure is completed within 4 days.

A structured protocol is presented for a cell-based assay as a functional test to predict the prognosis of idiopathic scoliosis using cellular dielectric spectroscopy (CDS). The assay can be performed with fresh or frozen peripheral blood mononuclear cells (PBMCs) and the procedure is completed within 4 days.

This protocol details the experimental and analytical procedure for a cell-based assay developed in our laboratory as a functional test to predict the ...

A Modified In vitro Invasion Assay to Determine the Potential Role of Hormones, Cytokines and/or Growth Factors in Mediating Cancer Cell Invasion

Blood serum serves as a chemoattractant towards which cancer cells migrate and invade, facilitating their intravasation into microvessels. However, the actual molecules towards which the cells migrate remain elusive. This modified invasion assay has been developed to identify targets which drive cell migration and invasion. This technique compares the invasion index under three conditions to determine whether a specific hormone, growth factor, or cytokine plays a role in mediating the invasive potential of a cancer cell. These conditions include i) normal fetal bovine serum (FBS), ii) charcoal-stripped FBS (CS-FBS), which removes hormones, growth factors, and cytokines and iii) CS-FBS + molecule (denoted &#8220;X&#8221;). A significant change in cell invasion with CS-FBS as compared to FBS, indicates the involvement of hormones, cytokines or growth factors in mediating the change. Individual molecules can then be added back to CS-FBS to assay their ability to reverse or rescue the invasion phenotype. Furthermore, two or more factors can be combined to evaluate the additive or synergistic effects of multiple molecules in driving or inhibiting invasion. Overall, this method enables the investigator to determine whether hormones, cytokines, and/or growth factors play a role in cell invasion by serving as chemoattractants or inhibitors of invasion for a particular type of cancer cell or a specific mutant. By identifying specific chemoattractants and inhibitors, this modified invasion assay may help to elucidate signaling pathways that direct cancer cell invasion.

A Modified In vitro Invasion Assay to Determine the Potential Role of Hormones, Cytokines and/or Growth Factors in Mediating Cancer Cell Invasion

This video article describes a modified in vitro method to examine the role of hormones, cytokines and/or growth factors in driving cancer cell invasion.

Blood serum serves as a chemoattractant towards which cancer cells migrate and invade, facilitating their intravasation into microvessels. However, the ...

A Simple Critical-sized Femoral Defect Model in Mice

While bone has a remarkable capacity for regeneration, serious bone trauma often results in damage that does not properly heal. In fact, one tenth of all limb bone fractures fail to heal completely due to the extent of the trauma, disease, or age of the patient. Our ability to improve bone regenerative strategies is critically dependent on the ability to mimic serious bone trauma in test animals, but the generation and stabilization of large bone lesions is technically challenging. In most cases, serious long bone trauma is mimicked experimentally by establishing a defect that will not naturally heal. This is achieved by complete removal of a bone segment that is larger than 1.5 times the diameter of the bone cross-section. The bone is then stabilized with a metal implant to maintain proper orientation of the fracture edges and allow for mobility. 
Due to their small size and the fragility of their long bones, establishment of such lesions in mice are beyond the capabilities of most research groups. As such, long bone defect models are confined to rats and larger animals. Nevertheless, mice afford significant research advantages in that they can be genetically modified and bred as immune-compromised strains that do not reject human cells and tissue.
Herein, we demonstrate a technique that facilitates the generation of a segmental defect in mouse femora using standard laboratory and veterinary equipment. With practice, fabrication of the fixation device and surgical implantation is feasible for the majority of trained veterinarians and animal research personnel. Using example data, we also provide methodologies for the quantitative analysis of bone healing for the model.

Animal models are frequently employed to mimic serious bone injury in biomedical research. Due to their small size, establishment of stabilized bone lesions in mice are beyond the capabilities of most research groups. Herein, we describe a simple method for establishing and analyzing experimental femoral defects in mice.

While bone has a remarkable capacity for regeneration, serious bone trauma often results in damage that does not properly heal. In fact, one tenth of all ...

A Simple Device to Rapidly Prepare Whole Mounts of the Mouse Intestine

Preparing whole mounts of the mouse small intestine and colon for subsequent analysis or quantification can be time consuming and difficult. We describe the use of a simple device to cut and &#8216;roll&#8217; mouse intestines to rapidly prepare whole mount preparations of superior and uniform quality to that which can be achieved by hand. The device comprises a base that holds 4 stainless steel rods and a top, which acts a cutting guide. The rods are inserted into the lumen of the small intestine [divided into thirds] and the colon. The rods and samples are then placed over a piece of filter paper or card into the holding slots in the base of the device. The top of the device is then positioned and serves as a cutting guide. The two angled sections in the center of the top piece are used to guide a knife or scalpel and cut the intestines longitudinally on the top of the rods. Once the intestinal sections have been cut, the top is removed and the card,&#160;tissue and rods gently removed from the device and placed on the bench. The rods are then gently rolled sideways to flatten and stick the intestinal segments onto the underlying piece of filter paper or card. The final preparation can then be examined or fixed and stored for later analysis. The preparations are invaluable for the study of intestinal changes in normal or genetically modified mouse models. The preparations have been used for the study and quantification of the effects of inflammation (colitis), damage, pre-cancerous lesions (aberrant crypt foci (ACFs) and mucin depleted foci (MDFs)) and polyps or tumors.

The use of a simple device to cut and &#8216;roll&#8217; mouse intestines to rapidly prepare whole mount preparations is described.

Preparing whole mounts of the mouse small intestine and colon for subsequent analysis or quantification can be time consuming and difficult. We describe ...

A High Throughput, Multiplexed and Targeted Proteomic CSF Assay to Quantify Neurodegenerative Biomarkers and Apolipoprotein E Isoforms Status

Many neurodegenerative diseases are&#160;still lacking effective treatments. Reliable biomarkers for identifying and classifying these diseases will be important in the development of future novel therapies. Often&#160;potential new biomarkers do not make it&#160;into the clinic&#160;due to limitations&#160;in their development and&#160;high costs.&#160;However,&#160;targeted proteomics using Multiple Reaction Monitoring Liquid Chromatography-tandem/Mass Spectrometry (MRM LC-MS/MS), specifically using triple quadrupole mass spectrometers, is one method that can be used to rapidly evaluate and validate biomarkers&#160;for clinical translation into diagnostic laboratories. Traditionally, this platform has been used extensively for measurement of small molecules&#160;in clinical laboratories, but it is the potential to analyze proteins, that makes it an attractive alternative to ELISA (Enzyme-Linked Immunosorbent Assay)-based methods. We describe here how targeted proteomics can be used to measure multiplexed markers of dementia, including the detection and quantitation of the known risk factor apolipoprotein E isoform 4 (ApoE4).
In order to make the assay suitable for translation, it is designed to be rapid, simple, highly specific and cost effective. To achieve this, every step in the development of the assay must be optimized for the individual proteins and tissues they are analyzed in. This method describes a typical workflow including various tips and tricks to developing a targeted proteomics MRM LC-MS/MS for translation.
The method development is optimized using custom synthesized versions of tryptic quantotypic peptides, which calibrate&#160;the MS for detection and then spiked into CSF to determine correct identification of the endogenous peptide in the chromatographic separation prior to analysis in the MS. To achieve absolute quantitation, stable isotope-labeled internal standard versions of the peptides with short amino acid sequence tags and containing a trypsin cleavage site, are included in the assay.

We describe a high-throughput, multiplex, and targeted proteomic cerebrospinal fluid (CSF) assay developed with potential for clinical translation. The test can quantitate potential markers and risk factors for neurodegeneration, such as the apolipoprotein E variants (E2, E3 and E4), and measure their allelic expression.

Many neurodegenerative diseases are&#160;still lacking effective treatments. Reliable biomarkers for identifying and classifying these diseases will be ...