The authors thank the technical staff at Nordic Bioscience for laboratory support, as well as the Danish Research Foundation for general support of our research.

1. Tissue isolation
<ol>
	<li>Tissue sourcing
	<ol>
		<li>Perform the entire tissue sourcing section outside a laminar flow hood in an aseptic environment.</li>
		<li>From the local slaughterhouse, obtain an entire fresh bovine tibiofemoral knee joint from calves between 1.5 and 2 years of age.</li>
		<li>Gently dissect the calf knee by first removing the excess flesh, uncovering the condyles, meniscus, tendons, and synovial membrane. Cut the tendons and synovial membrane, allowing the joint to dismember. Remove the me...

<ol>
	<li>Cope, P. J., Ourradi, K., Li, Y., Sharif, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Models+of+osteoarthritis:+the+good,+the+bad+and+the+promising.">Models of osteoarthritis: the good, the bad and the promising.</a> Osteoarthritis and Cartilage. 27 (2), 230-239 (2018).</li><li>Thysen, S., Luyten, F. P., Lories, R. J. U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Targets,+models+and+challenges+in+osteoarthritis+research.">Targets, models and challenges in osteoarthritis research.</a> Disease Models &amp; Mechanisms. 8 (1), 17-30 (2015).</li><li>Reker, D., 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=Articular+cartilage+from+osteoarthritis+patients+shows+extracellular+matrix+remodeling+over+the+course+of+treatment+with+sprifermin+(recombinant+human+fibroblast+growth+factor+18).">Articular cartilage from osteoarthritis patients shows extracellular matrix remodeling over the course of treatment with sprifermin (recombinant human fibroblast growth factor 18).</a> Osteoarthritis and Cartilage. 26, S43 (2018).</li><li>Kjelgaard-Petersen, C., 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=Synovitis+biomarkers:+ex+vivo+characterization+of+three+biomarkers+for+identification+of+inflammatory+osteoarthritis.">Synovitis biomarkers: ex vivo characterization of three biomarkers for identification of inflammatory osteoarthritis.</a> Biomarkers. 20 (8), 547-556 (2015).</li><li>Henriksen, K., 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=A+specific+subtype+of+osteoclasts+secretes+factors+inducing+nodule+formation+by+osteoblasts.">A specific subtype of osteoclasts secretes factors inducing nodule formation by osteoblasts.</a> Bone. 51 (3), 353-361 (2012).</li><li>Gigout, 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=Sprifermin+(rhFGF18)+enables+proliferation+of+chondrocytes+producing+a+hyaline+cartilage+matrix.">Sprifermin (rhFGF18) enables proliferation of chondrocytes producing a hyaline cartilage matrix.</a> Osteoarthritis and Cartilage. 25 (11), 1858-1867 (2017).</li><li>Reker, D., 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=Sprifermin+(rhFGF18)+modulates+extracellular+matrix+turnover+in+cartilage+explants+ex+vivo.">Sprifermin (rhFGF18) modulates extracellular matrix turnover in cartilage explants ex vivo.</a> Journal of Translational Medicine. 15 (1), 3560 (2017).</li><li>Karsdal, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Introduction.">Introduction.</a> Biochemistry of Collagens, Laminins and Elastin. , (2016).</li><li>Heineg&#229;rd, D., Saxne, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+the+cartilage+matrix+in+osteoarthritis.">The role of the cartilage matrix in osteoarthritis.</a> Nature Reviews Rheumatology. 7 (1), 50-56 (2011).</li><li>Karsdal, M. 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=Osteoarthritis&#8211;+a+case+for+personalized+health+care?.">Osteoarthritis&#8211; a case for personalized health care?.</a> Osteoarthritis and Cartilage. 22 (1), 7-16 (2014).</li><li>Karsdal, M. A., Bay-Jensen, A. C., Henriksen, K., Christiansen, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+pathogenesis+of+osteoarthritis+involves+bone,+cartilage+and+synovial+inflammation:+may+estrogen+be+a+magic+bullet?.">The pathogenesis of osteoarthritis involves bone, cartilage and synovial inflammation: may estrogen be a magic bullet?.</a> Menopause International. 18 (4), 139-146 (2012).</li><li>Loeser, R. F., Goldring, S. R., Scanzello, C. R., Goldring, M. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Osteoarthritis:+a+disease+of+the+joint+as+an+organ.">Osteoarthritis: a disease of the joint as an organ.</a> Arthritis and Rheumatism. 64 (6), 1697-1707 (2012).</li><li>Goldring, M. B., Goldring, S. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Osteoarthritis.">Osteoarthritis.</a> Journal of Cellular Physiology. 213 (3), 626-634 (2007).</li><li>Karsdal, M. 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=The+coupling+of+bone+and+cartilage+turnover+in+osteoarthritis:+opportunities+for+bone+antiresorptives+and+anabolics+as+potential+treatments?.">The coupling of bone and cartilage turnover in osteoarthritis: opportunities for bone antiresorptives and anabolics as potential treatments?.</a> Annals of the Rheumatic Diseases. 73 (2), 336-348 (2014).</li><li>Genovese, F., Karsdal, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protein+degradation+fragments+as+diagnostic+and+prognostic+biomarkers+of+connective+tissue+diseases:+understanding+the+extracellular+matrix+message+and+implication+for+current+and+future+serological+biomarkers.">Protein degradation fragments as diagnostic and prognostic biomarkers of connective tissue diseases: understanding the extracellular matrix message and implication for current and future serological biomarkers.</a> Expert Review of Proteomics. 13 (2), 213-225 (2016).</li><li>Gudmann, N. 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=Cartilage+turnover+reflected+by+metabolic+processing+of+type+II+collagen:+a+novel+marker+of+anabolic+function+in+chondrocytes.">Cartilage turnover reflected by metabolic processing of type II collagen: a novel marker of anabolic function in chondrocytes.</a> International Journal of Molecular Sciences. 15 (10), 18789-18803 (2014).</li><li>Madej, W., van Caam, A., Davidson, E. B., Buma, P., van der Kraan, P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Unloading+results+in+rapid+loss+of+TGF&#946;+signaling+in+articular+cartilage:+role+of+loading-induced+TGF&#946;+signaling+in+maintenance+of+articular+chondrocyte+phenotype?.">Unloading results in rapid loss of TGF&#946; signaling in articular cartilage: role of loading-induced TGF&#946; signaling in maintenance of articular chondrocyte phenotype?.</a> Osteoarthritis and Cartilage. 24 (10), 1807-1815 (2016).</li><li>Kjelgaard-Petersen, C. 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=Translational+biomarkers+and+ex+vivo+models+of+joint+tissues+as+a+tool+for+drug+development+in+rheumatoid+arthritis.">Translational biomarkers and ex vivo models of joint tissues as a tool for drug development in rheumatoid arthritis.</a> Arthritis &amp; Rheumatology. 70 (9), 1419-1428 (2018).</li><li>Wang, B., 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=Suppression+of+MMP+activity+in+bovine+cartilage+explants+cultures+has+little+if+any+effect+on+the+release+of+aggrecanase-derived+aggrecan+fragments.">Suppression of MMP activity in bovine cartilage explants cultures has little if any effect on the release of aggrecanase-derived aggrecan fragments.</a> BMC Research Notes. 2 (4), 259 (2009).</li><li>Bay-Jensen, A. C., 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=Enzyme-linked+immunosorbent+assay+(ELISAs)+for+metalloproteinase+derived+type+II+collagen+neoepitope,+CIIM&#8212;Increased+serum+CIIM+in+subjects+with+severe+radiographic+osteoarthritis.">Enzyme-linked immunosorbent assay (ELISAs) for metalloproteinase derived type II collagen neoepitope, CIIM&#8212;Increased serum CIIM in subjects with severe radiographic osteoarthritis.</a> Clinical Biochemistry. 44 (5-6), 423-429 (2011).</li><li>Lories, R. J., Luyten, 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=The+bone-cartilage+unit+in+osteoarthritis.">The bone-cartilage unit in osteoarthritis.</a> Nature Reviews Rheumatology. 7 (1), 43-49 (2011).</li></ol>

The protocol presented here for the profiling of cartilage tissue turnover in bovine cartilage explants can be used for characterizing treatment effects of many types of drugs, including inhibitors of inflammatory intracellular pathways, inhibitors of proteolytic enzymes, or anabolic growth factors.
Two different setups were described in this protocol: an anabolic setup where explants were stimulated with insulin-like growth factor 1 (IGF-1), and a catabolic setup comprising stimulation with T...

Chondrocytes produce and maintain the cartilage matrix. In order to study the biology of chondrocytes and how they and the surrounding ECM react to external stimuli, it is crucial to interrogate them in their native environment1,2. Studying cartilage tissue turnover is important to augment the understanding of the underlying mechanisms in joint diseases such as OA, a disease for which there is currently no disease modifying treatment. Consequently, there is a significant need for better translation models2.
Ex vivo characterization of cell and tissue effects is essential to complement other preclinical models, both in vitro, such as chondrocyte monolayer cultures, and in vivo, such as surgery-induced OA models or the autoimmune collagen-induced arthritis model (CIA). Numerous studies have highlighted the differences between how cells behave in 2D monolayer cultures and 3D structures or in their native tissue3,4. Many cells in 2D layers adopt unnatural morphologies, including differences in cell polarity and tissue attachment, resulting in both visual and functional differences in cells within native tissues5. The differences are also apparent in the functionality of the cells, which may shift protein expression, leading to profoundly altered differentiation patterns, regulatory machinery, and cell functionality5,6,7,8.
The cartilage ECM consists mainly of type II collagen providing a matrix framework, and aggrecan, a proteoglycan that helps retain fluid within the tissue. Other matrix molecules such as collagen type IV, VI, IX, X, XI, XII, fibronectin, cartilage oligomeric protein (COMP), biglycan, decorin, and perlecan are also present9.
While the aetiology of OA remains unclear10,11, the onset of the disease is believed to be caused by imbalances in tissue turnover and repair processes12,13. The degradation of the articular cartilage is a hallmark of OA. Cartilage-resident chondrocytes or cells in the surrounding tissues increase their release of cytokines, stimulating elevated production of proteinases such as matrix metalloproteinases (MMPs) and aggrecanases, which increase degradation of cartilage ECM14. This degradation results in the release of small unique protein fragments called neo-epitopes, which can be quantified in serum, urine, or culture medium15. Upon formation and maturation of collagen, so-called profragments are also released; these can be quantified as a measure of matrix production16.
The aim of this protocol is to establish an ex vivo cartilage model to compare the effect of stimulation and/or drug treatment on ECM tissue turnover. Cartilage turnover is profiled by measuring matrix-derived neo-epitope biomarkers directly in the conditioned culture medium using ELISA: AGNx1 (reflecting aggrecanase activity), C2M (reflecting matrix MMP activity), and ProC2 (reflecting type II collagen formation). The findings can be verified by histological staining of the ECM, which also visualizes the organization of chondrocytes in the individual explants. The described protocol can be used to test the effect of novel treatments on chondrocyte function and cartilage ECM turnover. A number of studies have used cartilage explants to describe biological processes or the effect of intervention on cytokine-challenged explants using quantitative histological or immunohistochemical approaches, mRNA, protein expression, or proteomics2,17,18. However, these protocols are outside the scope of the current manuscript.

<table>
	<tbody>
		<tr>
			<td>45% Iron(III) chloride solution</td>
			<td>Sigma-Aldrich</td>
			<td>12322</td>
			<td></td>
		</tr>
		<tr>
			<td>Acetic acid</td>
			<td>Merck</td>
			<td>1.00056.2500</td>
			<td></td>
		</tr>
		<tr>
			<td>Alamar Blue</td>
			<td>Life tech Invitrogen</td>
			<td>DAL1100</td>
			<td></td>
		</tr>
		<tr>
			<td>Biopsy processing cassettes &#8211; green</td>
			<td>IHCWORLD</td>
			<td>BC-0109G</td>
			<td></td>
		</tr>
		<tr>
			<td>Biopsy punch W/Plunger (3 mm)</td>
			<td>Scandidat</td>
			<td>MTP-33-32</td>
			<td></td>
		</tr>
		<tr>
			<td>Bovine cartilage (Bovine knees)</td>
			<td>Local slaughterhouse</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>C2M</td>
			<td>Nordic Bioscience</td>
			<td></td>
			<td>Fee for service</td>
		</tr>
		<tr>
			<td>Corning 96-well plate</td>
			<td>Sigma-Aldrich</td>
			<td>CLS7007</td>
			<td></td>
		</tr>
		<tr>
			<td>Cover Glass &#216; 13 mm</td>
			<td>VWR</td>
			<td>631-0150P</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM/F12-GlutaMAX Dulbecco&#39;s Modified Eagle Medium/Nutrient Mixture F-12) without HEPES</td>
			<td>Gibco</td>
			<td>31331-028</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol &#8805;96%</td>
			<td>VWR</td>
			<td>83804.36</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol absolute &#8805;99.5%</td>
			<td>VWR</td>
			<td>83813.36</td>
			<td></td>
		</tr>
		<tr>
			<td>exAGNx1</td>
			<td>Nordic Bioscience</td>
			<td></td>
			<td>Fee for service</td>
		</tr>
		<tr>
			<td>exPRO-C2</td>
			<td>Nordic Bioscience</td>
			<td></td>
			<td>Fee for service</td>
		</tr>
		<tr>
			<td>Fast green</td>
			<td>Sigma-Aldrich</td>
			<td>F7252</td>
			<td></td>
		</tr>
		<tr>
			<td>Formaldehyde solution 4%</td>
			<td>Merck</td>
			<td>1004965000</td>
			<td></td>
		</tr>
		<tr>
			<td>GM6001</td>
			<td>Sigma-Aldrich</td>
			<td>M5939-5MG</td>
			<td></td>
		</tr>
		<tr>
			<td>Hematoxylin</td>
			<td>Sigma-Aldrich</td>
			<td>H3136</td>
			<td></td>
		</tr>
		<tr>
			<td>Hydrochloric acid</td>
			<td>Merck</td>
			<td>30721-M</td>
			<td></td>
		</tr>
		<tr>
			<td>IGF-1</td>
			<td>Sigma-Aldrich</td>
			<td>I3769-50UG</td>
			<td></td>
		</tr>
		<tr>
			<td>Oncostatin M</td>
			<td>Sigma-Aldrich</td>
			<td>O9635-10UG</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin-streptomycin (P/S)</td>
			<td>Sigma-Aldrich</td>
			<td>P4333</td>
			<td></td>
		</tr>
		<tr>
			<td>Pertex (mounting medium for light microscopy)</td>
			<td>HistoLab</td>
			<td>811</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate Buffered Saline (PBS)</td>
			<td>Sigma-Aldrich</td>
			<td>D8537</td>
			<td></td>
		</tr>
		<tr>
			<td>Safranin O</td>
			<td>Sigma-Aldrich</td>
			<td>S2255</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile Standard Scalpels</td>
			<td>Integra Miltex</td>
			<td>12-460-451</td>
			<td></td>
		</tr>
		<tr>
			<td>Sulfuric acid</td>
			<td>Sigma-Aldrich</td>
			<td>30743</td>
			<td></td>
		</tr>
		<tr>
			<td>SUPERFROST PLUS Adhesion Microscope Slides</td>
			<td>Thermo scientific</td>
			<td>J1800AMNT</td>
			<td></td>
		</tr>
		<tr>
			<td>TNF-alpha</td>
			<td>R&#38;D Systems</td>
			<td>210-TA-100</td>
			<td></td>
		</tr>
		<tr>
			<td>Toluene</td>
			<td>Merck</td>
			<td>1.08327.2500</td>
			<td></td>
		</tr>
		<tr>
			<td>Vacuum Filtration &#34;rapid&#34;-Filtermax</td>
			<td>TPP</td>
			<td>99955</td>
			<td></td>
		</tr>
	</tbody>
</table>

an ex vivo tissue culture model of cartilage remodeling in bovine knee explants

Ex vivo culture systems cover a broad range of experiments dedicated to studying tissue and cellular function in a native setting. Cartilage is a unique tissue important for proper function of the synovial joint and is constituted by a dense extracellular matrix (ECM), rich in proteoglycan and type II collagen. Chondrocytes are the only cell type present within cartilage and are widespread and relatively low in number. Altered external stimuli and cellular signalling can lead to changes in ECM composition and deterioration, which are important pathological hallmarks in diseases such as osteoarthritis (OA) and rheumatoid arthritis.
Ex vivo cartilage models allow 1) profiling of chondrocyte mediated alterations of cartilage tissue turnover, 2) visualizing the cartilage ECM composition, and 3) chondrocyte rearrangement directly in the tissue. Profiling these alterations in response to stimuli or treatments are of high importance in various aspects of cartilage biology, and complement in vitro experiments in isolated chondrocytes, or more complex models in live animals where experimental conditions are more difficult to control.
Cartilage explants present a translational and easily accessible method for assessing tissue remodeling in the cartilage ECM in controllable settings. Here, we describe a protocol for isolating and culturing live bovine cartilage explants. The method uses tissue from the bovine knee, which is easily accessible from the local butchery. Both explants and conditioned culture medium can be analyzed to investigate tissue turnover, ECM composition, and chondrocyte function, thus profiling ECM modulation.

Bovine full-depth explants were isolated, cultured, and treated for 3 weeks (Figure 1). The culture medium was changed with the addition of treatment 3 times per week. Once weekly, metabolic activity was measured by the resazurin assay. Biomarkers of ECM turnover were measured in the supernatant harvested from the culture plate 3 times per week. Explants were divided into 4 groups for treatment: 1) Oncostatin M and TNF&#945; (O+T); 2) O+T + GM6001 (GM6001); 3) Insulin like Growth Factor-1 (I...

Watch this Scientific Journal Video about An Ex Vivo Tissue Culture Model of Cartilage Remodeling in Bovine Knee Explants at JoVE.com

An Ex Vivo Tissue Culture Model of Cartilage Remodeling in Bovine Knee Explants

Here, we present a protocol describing isolation and culturing of cartilage explants from bovine knees. This method provides an easy and accessible tool to describe tissue changes in response to biological stimuli or novel therapeutics targeting the joint.

Ex vivo culture systems cover a broad range of experiments dedicated to studying tissue and cellular function in a native setting. Cartilage is a unique ...

Cartilage implants represent a translational easily accessible method for interrogating tissue remodeling in the cartilage matrix. The method may provide early insight into how potential new treatments affect joint structure. The main advantage of this technique is that that cartilage remain in a native 3D environment, which allow profiling of the interaction between cells and the surrounding matrix using biomarkers.The principle in the method is not unique to cartilage. Explants can be extracted from other tissues such as an ovium, liver, and lung and interrogated using matrix derived biomarkers. Demonstrating the procedure will be Amalie Engstrom, a grad student from our laboratory.Perform the entire tissue sourcing process outside of a laminar flow hood in an aseptic environment. From a local slaughterhouse, obtain an entire fresh bovine tibial femoral knee joint from calves between 1.5 and two years of age. Then, gentle dissect the calf knee by first removing the excess flesh, uncovering the condyles, meniscus, tendons, and synovial membrane.Cut the tendons and synovial membrane allowing the joint to dismember. Remove the meniscus to expose the femoral condyles. Use a three millimeter biopsy puncher to isolate explants from the load bearing area of the femoral condyles and release them from auricular surface by cutting with a scalpel parallel to and as close to the subchondral bone as possible.Immediately store and mix the explants in DMEM F12 glutimax culture medium containing 1%penicillin and streptomycin in a 50 milliliter tube or Petri dish. To begin tissue culturing, transfer the explants to a sterile 96 well plate in a laminar flow hood placing all replicates within each group diagonally to minimize the variation induced by evaporation. Add PBS to the outer wells of the culture plate to further avoid evaporation of the supernatant.Then, wash the explants three times in either culture medium or PBS. Culture the explants in 200 microliters of culture medium per well until the start of the experiment for up to 10 weeks in an incubator at 37 degrees Celsius with 5%carbon dioxide. If applying any treatments, prepare these to the wanted concentration in the explant wells by dilution in the culture medium prior to changing the medium.Change the culture medium every two to three days in a laminar flow hood. Gently remove the supernatant from each well and transfer it to a new 96 well plate for storage. Immediately add 200 microliters of fresh culture medium or treatment to each well.Do not let the explants dry out during the medium change and ensure that all of the explants are completely submerged in the new medium. Seal the new plate with sealing tape and store it at minus 20 degrees Celsius for biomarker analysis of tissue turnover and protein expression. To begin a resazurin test, make a solution of culture medium containing 10%resazurin.Harvest the supernatant as previously described and immerse the explants in the 10%resazurin solution at 37 degrees Celsius for three hours or until the supernatants turn purple. Then, transfer the conditioned and background control resazurin solution to a black microtiter plate and measure the fluorescence at an excitation of 540 nanometers and an emission of 590 nanometers. After this, submerge the explants in wash medium for five to 10 minutes to allow the resazurin to completely diffuse out and add new culture medium or treatments if used.Continue measuring the metabolic activity once weekly as an indirect measurement of cell viability. In this study, bovine full depth explants are isolated, cultured, and treated. Explants are divided into four groups for treatment, including those treated with Oncostatin M and tumor necrosis factor alpha, those treated with Oncostatin M and tumor necrosis factor alpha with GM 6001, those treated with insulin growth factor one, and a control without treatment.The metabolic activity is relatively stable throughout the three weeks for all four groups. There was a tendency for IGF-1 to increase and O plus T groups to decrease compared to control. O plus T is then applied to culture wells three times a week to investigate O plus T mediated cartilage degradation.O plus T is seen to increase type two collagen degradation from day seven to 21 and aggrecan degradation from days three to 14 compared to the control group. Adding GM 6001 in combination with O plus T blocks the release of the O plus T mediated C2M, but only has limited affect on AGN X1 with levels similar to O plus T group at day 10. Insulin like growth factor one is applied three times weekly to bovine full depth explants to investigate how anabolic stimulation modules the cartilage ECM turnover.The effect of IGF-1 on the cartilage explants was mainly observed on measurements of type two collagen formation as expected for anabolic stimuli. When treating with IGF-1, the the pro-C2 levels decrease less than those observed in the control group, indicating that IGF-1 stimulates type two collagen formation from day seven. Explants may deteriorate over time and thus careful pipetting is critical in all treatment and washing steps in order to not lose or destroy explants in the different media exchange steps.Results generated using this model should not stand alone, but be supported by data generated in human tissue as well as cellular and in newer models to further validate findings. To shed light on the underlying mechanism in the tissue and not just the outcomes, it's possible to further analyze both tissue and supernatants using other molecular biology techniques, such as gene and protein expression analysis, or immunohistochemistry, or other permanent molecular biology techniques.

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JoVE Journal

Biology

9.1K 次观看.  Nordic Bioscience. 软骨植入物是一种可转换、易于访问的方法，用于询问软骨基质中的组织重塑。该方法可能提供早期洞察潜在的新疗法如何影响关节结构。该技术的主要优点是，软骨保留在本机 3D 环境中，允许使用生物标志物分析细胞与周围基质之间的相互作用。该方法的原理并非软骨所独有。外植物可以从其他组织（如卵巢、肝脏和肺）中提取，并使用基质衍生的生物标志物进行询...