This work was supported by AO Foundation and AOSpine International. Babak Saravi received fellowship support from the German Spine Foundation and the German Osteoarthritis Foundation. Gernot Lang was supported by the Berta-Ottenstein-Programme for Advanced Clinician Scientists, Faculty of Medicine, University of Freiburg, Germany.

Experiments were performed using bovine tails obtained from local abattoirs. The biological materials used in the current study are taken from the food chain and require no ethical approval in Swiss and European law.
1. Dissection of the bovine intervertebral disc
<ol>
	<li>Rinse the whole tail thoroughly with tap water to remove dirt and hair on the surface. 
	NOTE: With intact, distal ends, a maximum of 9 IVDs (coccygeal 1-9) per tail can be used for the experiments depending on the desired size of the IVDs. Considering the desired diameter between 15-20 mm, we used 12 bovine tails with 5 IVDs per tail for the experiments.</li>
	<li>Immerse the whole tail in a box containing 1% betadine solution for 10 min. Briefly dry the tail with sterile gauze and place it on a sterile drape. 
	NOTE: During dissection of the disc, humidify the tails with Ringer&#39;s solution wetted gauze to prevent dehydration. Store the tails (or left-over segments) wrapped in wet gauze until the whole dissection procedure is completed.</li>
	<li>Use a scalpel (No. 20) to remove the soft tissue as completely as possible from the caudal spine to facilitate the identification of the IVDs. Remove the spinous and transverse processes of the vertebrae with bone removal pliers. 
	NOTE: Select IVDs with the desired diameter. IVDs with a diameter range of 15-20 mm were used in the current study.</li>
	<li>Cut transversely with bone pliers through the middle of each vertebral body to obtain individual motion segments. Put motion segments in a Petri dish with gauze wetted with Ringer&#39;s solution.</li>
	<li>Locate the IVD and vertebra by palpation and by moving the motion segments gently. Make two parallel cuts with the band saw in the growth plate of the IVDs, one on each side of the IVD. Identify the location of the growth plate by touching and finding the convex site of the bony endplate part (hard) adjacent to the disc (soft) with a safety distance of approximately 0.5-1 mm from the IVD towards the vertebra. Ensure that the blade of the band saw is cooled with Ringer&#39;s solution while cutting the vertebrae.</li>
	<li>Transfer IVDs in a clean Petri dish with clean gauze wetted with Ringer&#39;s solution. 
	NOTE: The gauze should be moistened and not too wet to prevent swelling of the IVDs,</li>
	<li>Use the scalpel blade to scrape off the vertebral body (red/pink bone), growth plate (white cartilage), leave the endplate intact (yellow-pink). Make the two surfaces flat and parallel for the loading procedure. Transfer scraped IVDs to a fresh Petri dish with gauze wetted with Ringer&#39;s solution. 
	NOTE: Wear a chainmail glove to protect the hand while holding the IVD and scraping.</li>
	<li>Measure the disc height and diameter with a caliper. Clean the blood clots in the vertebrae bone with Ringer&#39;s solution using a jet lavage system.</li>
	<li>Transfer the IVDs to 50 mL plastic tubes, one IVD per tube. Add 25 mL of Phosphate-Buffered Saline (PBS) + 10% Penicillin/Streptomycin (P/S) per IVD and leave it shaking for 15 min on an orbital shaker at room temperature.</li>
	<li>Aspirate the supernatant and add 10 mL of PBS + 1% P/S per IVD for 2 min to rinse the IVDs.</li>
</ol>
2. IVD culture and loading
<ol>
	<li>Transfer discs to IVD chambers and add IVD culture medium (Dulbecco&#39;s Modified Eagle Medium (DMEM, 4.5 g/L high glucose DMEM for the physiological group and 2 g/L low glucose DMEM for the pathological group) + 1% P/S + 2% fetal calf serum + 1% ITS (contains 5 &#181;g/mL insulin, 6 &#181;g/mL transferrin, and 5 ng/mL selenious acid) + 50 &#181;g/mL ascorbate-2-phosphate + 1% non-essential amino acid + 50 &#181;g/mL antimicrobial agent&#160;for primary cells) and place in an incubator at 37 &#176;C, 85% humidity and 5% CO2.</li>
	<li>Culture the discs for 4 days within a bioreactor system according to experimental groups16. In the pathologic group, maintain degenerative loading conditions at 0.32-0.5 MPa, 5 Hz for 2 h/day. In the physiological control group, use a loading protocol of 0.02-0.2 MPa, 0.2 Hz for 2 h/day. 
	NOTE: Position the IVDs in chambers containing 5 mL of IVD medium during the loading procedures. The volume depends on the size of the bioreactor&#39;s loading chambers. Between the loading procedures, place the IVDs in six-well plates with 7 mL of IVD culture medium for free-swelling recovery.</li>
	<li>For analyzing the changes in disc height during the experimental period, measure the disc height with a caliper after IVD dissection (baseline) and then daily after the free swelling period and after dynamic loading for the experimental duration.</li>
</ol>
3. Intradiscal tumor necrosis factor-alpha (TNF-&#945;) injection
<ol>
	<li>Directly after the first dynamic loading cycle on day 1, place the IVDs in a Petri dish in a vertical position and stabilize the IVDs with a tweezer.</li>
	<li>Inject recombinant TNF-&#945; (100 ng in 70 &#181;L of PBS per IVD) with a 30-gauge insulin needle into the nucleus pulposus tissue of the pathological group17. Inject slowly at a speed of approximately 70 &#181;L in 1 min.</li>
	<li>After injection, pull the syringe halfway back within the IVD and pull the syringe plunger to create a vacuum that prevents the injected solution from leaking back, before removing the needle and syringe completely from the IVD. 
	&#8203;NOTE: Perform a pilot experiment by injecting PBS containing trypan blue dye to evaluate the distribution of the injected solution after loading and overnight culture.</li>
</ol>
4. Gene expression
<ol>
	<li>Harvest the IVDs on day 4. Collect the nucleus pulposus (NP) tissue (gelly part in the middle of IVD) with a biopsy punch. Collect the outer annulus fibrosus (AF) with a scalpel blade (No.20). 
	NOTE: For the baseline reference at day 0, collect&#160;tissues immediately after dissection for RNA extraction.</li>
	<li>Use the amount of NP or AF tissue needed for gene expression analysis, depending on the experimental design. 
	NOTE: For the present experiments, approximately 150 mg tissue was used. The ratio of RNA isolation solution to tissue mass should be at least 2 mL per 100-150 mg tissue for efficient extraction.</li>
	<li>Digest the NP or AF tissue with the digestion solution (0.2% pronase in DMEM, filter sterilized) and incubate for 1 h at 37 &#176;C with magnetic stirring18.</li>
	<li>Flash-freeze the tissue samples using liquid nitrogen and pulverize to a fine powder. Divide the pulverized tissue powder equally into two 2 mL tubes each containing 1 mL of guanidine thiocyanate and phenol in a monophase solution (RNA isolation solution).</li>
	<li>Perform the homogenization in 2 mL tubes containing the RNA isolation solution and the pulverized tissue powder. Homogenize the tissue powder 5x with an 8 mm stainless steel ball and a tissue-lyzer at 30 Hz for 3 min. Centrifuge at 12,000 x g, 4 &#176;C for 10 min and transfer the supernatant to a fresh tube. The supernatants can be stored at -80 &#176;C for at least one month.</li>
	<li>Add 0.1 mL of 1-bromo-3-chloropropane (BCP) per 1 mL of RNA isolation solution and shake vigorously for 15 s. Store the resulting mixture at room temperature on an orbital shaker for 15 min and centrifuge at 12,000 x g for 15 min at 4 &#176;C. 
	NOTE: The RNA remains exclusively in the upper aqueous phase.</li>
	<li>Transfer the aqueous phase into a fresh tube and precipitate RNA with 0.25 mL of isopropanol and 0.25 mL of high salt precipitation solution per 1 mL of RNA isolation solution used for initial homogenization. Store the samples at room temperature for 15 min on an orbital shaker and centrifuge at 12,000 x g for 8 min at 4 &#176;C. 
	&#8203;NOTE: Alternatively, use the column-based RNA extraction method which generally leads to higher RNA purity but lower RNA yield.</li>
	<li>Remove the supernatant and wash the RNA pellet with 1 mL of 75% ethanol per 1 mL of RNA isolation solution used for initial homogenization. Centrifuge at 7,500 x g for 5 min at 4 &#176;C.</li>
	<li>Remove the ethanol wash and briefly air-dry RNA pellet for 3-5 min. Dissolve the RNA in 20 &#181;L of diethylpyrocarbonate (DEPC) treated water by passing the solution a few times through a pipette tip and incubating for 10-15 min at 55-60 &#176;C.</li>
	<li>Measure the absorbance at 230 nm, 260 nm, and 280 nm (A230, A260 and A280 respectively). A260 of 1.0 corresponds to 40 &#181;g/mL RNA. An A260/A280 ratio of 1.6-1.9 is expected, whereas contamination results in a A260/A280 ratio of &#60;1.6.</li>
	<li>Prepare a reverse transcriptase (RT) reaction mix for a 20 &#181;L reaction volume. The mix contains RT enzyme mix, ribonuclease inhibitor, helper protein, primers, dNTPs, MgCl2, RNase free water, and 0.4 &#956;g of RNA sample.</li>
	<li>Briefly centrifuge the RT tubes to mix all the components at the bottom of the tube.</li>
	<li>Place the samples in the thermocycler instrument. Select the appropriate program for the RT. Run the RT for 10 min at 25 &#176;C, followed by the reverse transcription step for 120 min at 42 &#176;C and inactivation of the reverse transcriptase for 5 min at 85 &#176;C, cooling it down to 4 &#176;C at the end.</li>
	<li>Dilute the resulting cDNA with Tris(hydroxymethyl)aminomethane (Tris)-ethylenediaminetetraacetic acid (EDTA) (TE) buffer (10 mM Tris with 1 mM EDTA) to a final concentration of 0.4 &#181;g RNA used for RT per 100 &#181;L cDNA solution. Store the cDNA samples at -20 &#176;C.</li>
	<li>Perform real-time polymerase chain reaction (PCR) using a 10 &#181;L reaction volume. The reaction volume contains the master mix (containing DNA polymerase, uracil-DNA glycosylase, dNTPs with dUTP, passive reference and optimized buffer components), forward primer 45 &#181;M, reverse primer 45 &#181;M, probe 12.5 &#181;M (containing a reporter dye linked to the 5&#39; end of the probe, a minor groove binder at the 3&#39; end of the probe, and a nonfluorescent quencher at the 3&#39; end of the probe), 2 &#181;L cDNA and DEPC-treated water.</li>
	<li>Run an endogenous control (RPLP0) for relative quantification with the 2-&#916;&#916;CT method19.</li>
	<li>Add samples in duplicates and run a no template control by adding TE-buffer instead of cDNA. Run PCR at standard conditions (2 min at 50 &#176;C, 10 min at 95 &#176;C, 40 cycles of 15 s at 95 &#176;C, and 1 min at 60 &#176;C).</li>
	<li>Perform relative quantification of mRNA targets following the comparative CT method. The amount of mRNA normalized to the baseline sample is calculated as 2-&#916;&#916;CT, whereas &#916;&#916;CT is the difference between the &#916;CT (CT target- CT endogenous control) of sample and &#916;CT (CT target and CT endogenous control) of the baseline sample.</li>
</ol>
5. Quantification of protein content in the IVD medium
<ol>
	<li>Collect the medium conditioned by the IVD samples to measure the protein content in the medium. Perform enzyme-linked immunosorbent assay (ELISA) according to the protocol of the target protein.</li>
	<li>Bovine interleukine-8 (IL-8) is quantified by anti-bovine IL8 ELISA kit according to the manufacturer&#39;s instruction.</li>
</ol>

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C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+and+validation+of+a+bioreactor+system+for+dynamic+loading+and+mechanical+characterization+of+whole+human+intervertebral+discs+in+organ+culture.">Development and validation of a bioreactor system for dynamic loading and mechanical characterization of whole human intervertebral discs in organ culture.</a> Journal of Biomechanics. 47 (9), 2095-2101 (2014).</li><li>Rajan, N. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Toll-Like+Receptor+4+(TLR4)+Expression+and+Stimulation+in+a+Model+of+Intervertebral+Disc+Inflammation+and+Degeneration.">Toll-Like Receptor 4 (TLR4) Expression and Stimulation in a Model of Intervertebral Disc Inflammation and Degeneration.</a> Spine. 38 (16), 1343-1351 (2013).</li><li>vanden Akker, G. G., Rorije, A. J., Davidson, E. N. B., vander 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=Phenotypic+marker+genes+distinguish+inner+and+outer+annulus+fibrosus+from+nucleus+pulposus+tissue+in+the+bovine+intervertebral+disc.">Phenotypic marker genes distinguish inner and outer annulus fibrosus from nucleus pulposus tissue in the bovine intervertebral disc.</a> Osteoarthritis and Cartilage. 25, 402 (2017).</li><li>Du, J., 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=Functional+cell+phenotype+induction+with+TGF-&#946;1+and+collagen-polyurethane+scaffold+for+annulus+fibrosus+rupture+repair.">Functional cell phenotype induction with TGF-&#946;1 and collagen-polyurethane scaffold for annulus fibrosus rupture repair.</a> European Cells &amp; Materials. 39, 1-17 (2020).</li><li>Risbud, M. V., 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=Defining+the+phenotype+of+young+healthy+nucleus+pulposus+cells:+recommendations+of+the+Spine+Research+Interest+Group+at+the+2014+annual+ORS+meeting.">Defining the phenotype of young healthy nucleus pulposus cells: recommendations of the Spine Research Interest Group at the 2014 annual ORS meeting.</a> Journal of Orthopaedic Research: Official Publication of the Orthopaedic Research Society. 33 (3), 283-293 (2015).</li></ol>

The authors have nothing to disclose.

We here provided a detailed protocol to simulate degenerative and inflammatory IVDD. This protocol can be applied for detailed examinations of inflammatory pathways leading to the destructive effects on the disc. Moreover, the protocol can help to determine promising therapeutic targets involved in the progression of the disease.
We recently showed that human recombinant TNF-&#945; could induce inflammation in both bovine and human NP cells21, which is in accordance wit...

Low back pain (LBP) can affect individuals of all ages and is a leading cause for disability worldwide1,2,3. The total cost associated with LBP exceeds $100 billion per year4,5. Symptomatic intervertebral disc (IVD) degeneration (IDD), a condition characterized by inflammation and tissue degradation, is a major cause of LBP6,7. Specifically, IDD is characterized by a gradually evolving breakdown of the IVD&#39;s extracellular matrix (ECM), induced and triggered by multiple factors that lead to an accelerated pathology, neurological disorders, and eventually disability. Furthermore, IDD is associated with the release of proinflammatory cytokines, altered spine biomechanics, angiogenesis, and nerve ingrowth, which increases pain sensation, altogether causing chronic LBP (active discopathy)6,8. To date, treatment options include discectomy and subsequent fusion of the adjacent vertebrae, implantation of an IVD prosthesis, or non-surgical approaches, such as non-steroidal anti-inflammatory drugs, opioids, and muscle relaxants for patients with IDD9. Both current standard therapeutic options, surgical and non-surgical, are only partly effective and fail to address the underlying biological problem9,10. Early-stage degenerative disc disease is characterized by an initial inflammatory tissue response, especially an increase in tumor necrosis factor-alpha (TNF-alpha) expression11. These early disc changes primarily occur at the cellular level without disrupting the disc architecture and could previously be mimicked by nutritional deficiency under pro-inflammatory conditions12. Therefore, precise simulation of the in vivo situation to investigate these degeneration mechanisms and find suitable therapeutic targets is crucial. Additionally, to these simulations of molecular properties, the mechanical loading environment of the discs plays a key role in pathological and physiological changes of IVD. Consequently, combining these approaches would bring us one step forward to mimic the complex microenvironment of IVDs in vivo. There are currently no studies considering the aspect of dynamic loading along with the pro-inflammatory and nutritional setting to the best of our knowledge.
Although large animal models allow the investigation of potential relevant in vivo interactions, they are costly and work intensive. Moreover, as the use of animal models in research has long been a matter of controversy, the reduction of the number of animals needed to answer important research questions is of great interest. Finally, there is currently no ideal animal model to mimic IDD in IVD research13,14. Therefore, it is necessary to establish a cost-effective and reliable replacement, such as an organ culture model to simulate IDD and associated inflammatory and degenerative processes. Recently, the application of the present protocol on the establishment of a proinflammatory and degenerative organ culture model to simulate early-stage intervertebral disc disease allowed us to investigate the effect of anti-inflammatory drugs in the IDD organ culture15.
Here, we describe how to obtain bovine intervertebral discs and induce the state of early-stage IDD via a catabolic and proinflammatory microenvironment caused by direct intradiscal injection of tumor necrosis factor-alpha (TNF-&#945;) and degenerative loading in a bioreactor under low nutritive medium conditions. Figure 1 illustrates the experimental model and shows the bioreactor used to simulate degenerative and physiological loading conditions.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/62100/62100fig01.jpg" /> 
Figure 1: Illustration of the experimental setup. A: bovine tail; B: dissected bovine intervertebral discs; C: transfer of the disc to a well-plate with culture medium; D: loading the simulation in a bioreactor; E: intradiscal injection technique; F: IVD after injection of PBS/trypan blue dye to reveal distribution. IDD: intervertebral disc degeneration. <a href="https://www.jove.com/files/ftp_upload/62100/62100fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

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	<tbody>
		<tr>
			<td>1-Bromo-3-chloropropane(BCP)</td>
			<td>Sigma-Aldrich, St. Louis, USA</td>
			<td>B9673</td>
			<td></td>
		</tr>
		<tr>
			<td>Ascorbate-2-phosphate</td>
			<td>Sigma-Aldrich, St. Louis, USA</td>
			<td>A8960</td>
			<td></td>
		</tr>
		<tr>
			<td>Band saw</td>
			<td>Exakt Apparatebau, Norderstedt, Germany</td>
			<td>model 30/833</td>
			<td></td>
		</tr>
		<tr>
			<td>Betadine</td>
			<td>Munndipharma, Frankfurt, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Bovine IL-8 Do.it-Yourself ELISA</td>
			<td>Kingfisher Biotech, St. Paul, USA</td>
			<td>DIY1028B-003</td>
			<td></td>
		</tr>
		<tr>
			<td>Corning ITS Premix</td>
			<td>Corning Inc., New York, USA</td>
			<td>354350</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM high glucose</td>
			<td>Gibco by life technologies, Carlsbad, USA</td>
			<td>10741574</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM low glucose</td>
			<td>Gibco by life technologies, Carlsbad, USA</td>
			<td>11564446</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol for molecular biology</td>
			<td>Sigma-Aldrich, St. Louis, USA</td>
			<td>09-0851</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum (FBS)</td>
			<td>Gibco by life technologies, Carlsbad, USA</td>
			<td>A4766801</td>
			<td></td>
		</tr>
		<tr>
			<td>Non-essential amino acid solution</td>
			<td>Gibco by life technologies, Carlsbad, USA</td>
			<td>11140050</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin/Streptomycin(P/S)</td>
			<td>gibco by life technologies, Carlsbad, USA</td>
			<td>11548876</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate Buffer Solution, tablet</td>
			<td>Sigma-Aldrich, St. Louis, USA</td>
			<td>P4417</td>
			<td></td>
		</tr>
		<tr>
			<td>Pronase</td>
			<td>Sigma-Aldrich, St. Louis, USA</td>
			<td>10165921001</td>
			<td></td>
		</tr>
		<tr>
			<td>Primocin</td>
			<td>InvivoGen, Sandiego, USA</td>
			<td>ant-pm-05</td>
			<td></td>
		</tr>
		<tr>
			<td>Pulsavac Jet Lavage System</td>
			<td>Zimmer, IN,USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>TissueLyser II</td>
			<td>Quiagen, Venlo, Netherlands</td>
			<td>85300</td>
			<td></td>
		</tr>
		<tr>
			<td>Streptavidinn-HRP</td>
			<td>Kingfisher Biotech, St. Paul, USA</td>
			<td>AR0068-001</td>
			<td></td>
		</tr>
		<tr>
			<td>Superscript VILO</td>
			<td>Invitrogen by life Technologies, Carlsbad, USA</td>
			<td>10704274</td>
			<td></td>
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		<tr>
			<td>cDNA Synthesis Kit</td>
			<td>Applied Biosystems by life technologies</td>
			<td>10400745</td>
			<td></td>
		</tr>
		<tr>
			<td>TaqMan Universal Master Mix</td>
			<td>Applied Biosystems by life technologies</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>TNF-alpha, recombinant human protein</td>
			<td>R&#38;D systems, Minnesota, USA</td>
			<td>210-TA-005</td>
			<td></td>
		</tr>
		<tr>
			<td>TRI Reagent</td>
			<td>Molecular Research Center, Cincinnati, USA</td>
			<td>TR 118</td>
			<td></td>
		</tr>
		<tr>
			<td>Tris-EDTA buffer solution</td>
			<td>sigma-Aldrich, St. Louis, USA</td>
			<td>93283</td>
			<td></td>
		</tr>
		<tr>
			<td>Gene bIL-6</td>
			<td>Applied Biosystems by life technologies</td>
			<td>Custom made probes</td>
			<td>Primer fw (5&#8242;&#8211;3&#8242;) TTC CAA AAA TGG AGG AAA AGG A 
			Primer rev (5&#8242;&#8211;3&#8242;) TCC AGA AGA CCA GCA GTG GTT 
			Probe (5&#8242;FAM/3&#8242;TAMRA) CTT CCA ATC TGG GTT CAA TCA GGC GATT</td>
		</tr>
		<tr>
			<td>Gene bIL8</td>
			<td>Applied Biosystems by life technologies</td>
			<td>Bt03211906_m1</td>
			<td></td>
		</tr>
		<tr>
			<td>Gene bTNF-alpha</td>
			<td>Applied Biosystems by life technologies</td>
			<td>Custom made probes</td>
			<td>Primer fw (5&#8242;&#8211;3&#8242;) CCT CTT CTC AAG CCT CAA GTA ACA A 
			Primer rev (5&#8242;&#8211;3&#8242;) GAG CTG CCC CGG AGA GTT 
			Probe (5&#8242;FAM/3&#8242;TAMRA) ATG TCG GCT ACA ACG TGG GCT ACC G</td>
		</tr>
		<tr>
			<td>GENE bIL1beta</td>
			<td>Applied Biosystems by life technologies</td>
			<td>Custom made probes</td>
			<td>Primer fw (5&#8242;&#8211;3&#8242;) TTA CTA CAG TGA CGA GAA TGA GCT GTT 
			Primer rev (5&#8242;&#8211;3&#8242;) GGT CCA GGT GTT GGA TGC A 
			Probe (5&#8242;FAM/3&#8242;TAMRA) CTC TTC ATC TGT TTA GGG TCA TCA GCC TCA A</td>
		</tr>
		<tr>
			<td>RPLP0</td>
			<td>Applied Biosystems by life technologies</td>
			<td>Bt03218086_m1</td>
			<td></td>
		</tr>
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</table>

a proinflammatory, degenerative organ culture model to simulate early-stage intervertebral disc disease.

Symptomatic intervertebral disc (IVD) degeneration (IDD) is a major socioeconomic burden and is characterized by inflammation and tissue degradation. Due to the lack of causative therapies, there is an urgent need for innovative experimental organ culture models to study the mechanisms involved in the progression of the disease, find therapeutic targets, and reduce the need for animal models. We here present a novel, three-dimensional organ culture model protocol mimicking the proinflammatory and catabolic microenvironment, which is present during IDD. 
Initially, bovine caudal IVDs were dissected, cleaned, and cultured in the tissue culture medium. Dynamic physiologic or pathologic loading was applied in a custom-made bioreactor for 2 hours per day. IVDs were assigned to a control group (high glucose medium, physiological loading, phosphate-buffered saline injection) and a pathological group (low glucose medium, pathological loading, tumor necrosis factor-alpha injection) for four days. Gene expression analysis from collected nucleus pulposus cells of the IVDs and enzyme-linked immunosorbent assay of the conditioned organ culture media was performed. 
Our data revealed a higher expression of inflammatory markers and reduced disc heights after loading in the pathological group compared to the control group. This protocol is reliable to simulate IVD inflammation and degeneration and can be further expanded to broaden its application scope.

Degenerative loading in low glucose medium combined with TNF-&#945; injection caused a significant increase of the gene expression of proinflammatory markers interleukin 6 (IL-6) and interleukin 8 (IL-8) compared to the physiological control group in NP cells after 4 days of culture (Figure 2). In contrast, we did not observe significant changes for the proinflammatory genes interleukin 1&#946; (IL-1&#946;) and TNF-&#945; in NP cells (data not shown). Furthermore, degenerative culture condit...

Watch this Scientific Journal Video about A Proinflammatory, Degenerative Organ Culture Model to Simulate Early-Stage Intervertebral Disc Disease. at JoVE.com

A Proinflammatory, Degenerative Organ Culture Model to Simulate Early-Stage Intervertebral Disc Disease.

This protocol presents a novel experimental model of proinflammatory, degenerative bovine organ culture to simulate early-stage intervertebral disc degeneration.

Symptomatic intervertebral disc (IVD) degeneration (IDD) is a major socioeconomic burden and is characterized by inflammation and tissue degradation. Due ...

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3.5K Views.  AO Research Institute Davos, Davos, Switzerland. This protocol presents a novel experimental model of proinflammatory, degenerative bovine organ culture to simulate early-stage intervertebral disc degeneration.

Video: A Proinflammatory, Degenerative Organ Culture Model to Simulate Early-Stage Intervertebral Disc Disease.

Murine Corneal Transplantation: A Model to Study the Most Common Form of Solid Organ Transplantation

Corneal transplantation is the most common form of organ transplantation in the United States with between 45,000 and 55,000 procedures performed each year. While several animal models exist for this procedure and mice are the species that is most commonly used. The reasons for using mice are the relative cost of using this species, the existence of many genetically defined strains that allow for the study of immune responses, and the existence of an extensive array of reagents that can be used to further define responses in this species. This model has been used to define factors in the cornea that are responsible for the relative immune privilege status of this tissue that enables corneal allografts to survive acute rejection in the absence of immunosuppressive therapy. It has also been used to define those factors that are most important in rejection of such allografts. Consequently, much of what we know concerning mechanisms of both corneal allograft acceptance and rejection are due to studies using a murine model of corneal transplantation. In addition to describing a model for acute corneal allograft rejection, we also present for the first time a model of late-term corneal allograft rejection.

Mice have been used as a model for studying many forms of transplantation, including corneal transplantation. We describe in this report a murine model for both acute and late-term corneal transplantation.

Corneal transplantation is the most common form of organ transplantation in the United States with between 45,000 and 55,000 procedures performed each ...

Method of Isolated Ex Vivo Lung Perfusion in a Rat Model: Lessons Learned from Developing a Rat EVLP Program

The number of acceptable donor lungs available for lung transplantation is severely limited due to poor quality. Ex-Vivo Lung Perfusion (EVLP) has allowed lung transplantation in humans to become more readily available by enabling the ability to assess organs and expand the donor pool. As this technology expands and improves, the ability to potentially evaluate and improve the quality of substandard lungs prior to transplant is a critical need. In order to more rigorously evaluate these approaches, a reproducible animal model needs to be established that would allow for testing of improved techniques and management of the donated lungs as well as to the lung-transplant recipient. In addition, an EVLP animal model of associated pathologies, e.g., ventilation induced lung injury (VILI), would provide a novel method to evaluate treatments for these pathologies. Here, we describe the development of a rat EVLP lung program and refinements to this method that allow for a reproducible model for future expansion. We also describe the application of this EVLP system to model VILI in rat lungs. The goal is to provide the research community with key information and &#8220;pearls of wisdom&#8221;/techniques that arose from trial and error and are critical to establishing an EVLP system that is robust and reproducible.

Method of Isolated Ex Vivo Lung Perfusion in a Rat Model: Lessons Learned from Developing a Rat EVLP Program

Ex-Vivo Lung Perfusion (EVLP) has allowed lung transplantation in humans to become more readily available by enabling the ability to assess organs and expand the donor pool. Here, we describe the development of a rat EVLP program and refinements that allow for a reproducible model for future expansion.

The number of acceptable donor lungs available for lung transplantation is severely limited due to poor quality. Ex-Vivo Lung Perfusion (EVLP) has allowed ...

Method of Direct Segmental Intra-hepatic Delivery Using a Rat Liver Hilar Clamp Model

Major hepatic surgery with inflow occlusion, and liver transplantation, necessitate a period of warm ischemia, and a period of reperfusion leading to ischemia/reperfusion (I/R) injury with myriad negative consequences. Potential I/R injury in marginal organs destined for liver transplantation contributes to the current donor shortage secondary to a decreased organ utilization rate. A significant need exists to explore hepatic I/R injury in order to mediate its impact on graft function in transplantation. Rat liver hilar clamp models are used to investigate the impact of different molecules on hepatic I/R injury. Depending on the model, these molecules have been delivered using inhalation, epidural infusion, intraperitoneal injection, intravenous administration or injection into the peripheral superior mesenteric vein. A rat liver hilar clamp model has been developed for use in studying the impact of pharmacologic molecules in ameliorating I/R injury. The described model for rat liver hilar clamp includes direct cannulation of the portal supply to the ischemic hepatic segment via a side branch of the portal vein, allowing for direct segmental hepatic delivery. Our approach is to induce ischemia in the left lateral and median lobes for 60 min, during which time the substance under study is infused. In this case, pegylated-superoxide dismutase (PEG-SOD), a free radical scavenger, is infused directly into the ischemic segment. This series of experiments demonstrates that infusion of PEG-SOD is protective against hepatic I/R injury. Advantages of this approach include direct injection of the molecule into the ischemic segment with consequent decrease in volume of distribution and reduction in systemic side effects.

A unique rat liver hilar clamp model was developed for studying the impact of pharmacologic molecules in ameliorating ischemia-reperfusion injury. This model includes direct cannulation of the portal supply to the ischemic liver segment via a branch of the portal vein, allowing for direct hepatic delivery.

Major hepatic surgery with inflow occlusion, and liver transplantation, necessitate a period of warm ischemia, and a period of reperfusion leading to ...

A Model to Simulate Clinically Relevant Hypoxia in Humans

In case of apnea, arterial partial pressure of oxygen (pO2) decreases, while partial pressure of carbon dioxide (pCO2) increases. To avoid damage to hypoxia sensitive organs such as the brain, compensatory circulatory mechanisms help to maintain an adequate oxygen supply. This is mainly achieved by increased cerebral blood flow. Intermittent hypoxia is a commonly seen phenomenon in patients with obstructive sleep apnea. Acute airway obstruction can also result in hypoxia and hypercapnia. Until now, no adequate model has been established to simulate these dynamics in humans. Previous investigations focusing on human hypoxia used inhaled hypoxic gas mixtures. However, the resulting hypoxia was combined with hyperventilation and is therefore more representative of high altitude environments than of apnea. Furthermore, the transferability of previously performed animal experiments to humans is limited and the pathophysiological background of apnea induced physiological changes is poorly understood. In this study, healthy human apneic divers were utilized to mimic clinically relevant hypoxia and hypercapnia during apnea. Additionally, pulse-oximetry and Near Infrared Spectroscopy (NIRS) were used to evaluate changes in cerebral and peripheral oxygen saturation before, during, and after apnea.

Hypoxia simulation in humans has usually been performed by inhaling hypoxic gas mixtures. For this study, apneic divers were used to simulate dynamic hypoxia in humans. Additionally, physiological changes in desaturation and re-saturation kinetics were evaluated with non-invasive tools such as Near-Infrared-Spectroscopy (NIRS) and peripheral oxygenation saturation (SpO2).

In case of apnea, arterial partial pressure of oxygen (pO2) decreases, while partial pressure of carbon dioxide (pCO2) increases. To avoid damage to ...

Ovine Lumbar Intervertebral Disc Degeneration Model Utilizing a Lateral Retroperitoneal Drill Bit Injury

Intervertebral disc degeneration is a significant contributor to the development of back pain and the leading cause of disability worldwide. Numerous animal models of intervertebral disc degeneration have been developed. The ideal animal model should closely mimic the human intervertebral disc with regard to morphology, biomechanical properties and the absence of notochordal cells. The sheep lumbar intervertebral disc model fulfils these criteria. We present an ovine model of intervertebral disc degeneration utilizing a drill bit injury through a lateral retroperitoneal approach. The lateral approach significantly reduces the incision and potential morbidity associated with the traditional anterior approach to the ovine spine. Utilization of a drill-bit method of injury affords the ability to produce a consistent and reproducible injury, of precise dimensions, that initiates a consistent degree of intervertebral disc degeneration. The focal nature of the annular and nucleus pulposus defect more closely mimics the clinical condition of focal intervertebral disc herniation. Sheep recover rapidly following this procedure and are typically mobile and eating within the hour. Intervertebral disc degeneration ensues and sheep undergo necropsy and subsequent analysis at periods from eight weeks. We believe that the drill bit injury model of intervertebral disc degeneration offers advantages over more conventional annular injury models.

Intervertebral disc degeneration is a significant contributor to back pain and a leading cause of disability worldwide. Numerous animal models of intervertebral disc degeneration exist. We demonstrate an ovine model of intervertebral disc degeneration, utilizing a drill bit, which achieves a consistent disc injury and reproducible level of disc degeneration.

Intervertebral disc degeneration is a significant contributor to the development of back pain and the leading cause of disability worldwide. Numerous ...

A Protocol to Acquire the Degenerative Tenocyte from Humans

Tendinopathy, a painful condition that develops in response to tendon degeneration, is on the rise in the developed world due to increasing physical activity and longer life expectancy. Despite its increasing prevalence, the underlying pathogenesis still remains unclear, and treatment is generally symptomatic. Recently, numerous therapeutic options, including growth factors, stem cells, and gene therapy, were investigated in hopes of enhancing the healing potency of the degenerative tendon. However, the majority of these research studies were conducted only on animal models or healthy human tenocytes. Despite some studies using pathological tenocytes, to the best of our knowledge there is currently no protocol describing how to obtain human degenerative tenocytes. The aim of this study is to describe a standard protocol for acquiring human degenerative tenocytes. Initially, the tendon tissue was harvested from a patient with lateral epicondylitis during surgery. Then biopsy samples were taken from the extensor carpi radialis brevis tendon corresponding to structural changes observed at the time of surgery. All of the harvested tendons appeared to be dull, gray, friable, and edematous, which made them visually distinct from the healthy ones. Tenocytes were cultured and used for experiments. Meanwhile, half of the harvested tissues were analyzed histologically, and it was shown that they shared the same key features of tendinopathy (angiofibroblastic dysplasia or hyperplasia). A secondary analysis by immunocytochemistry confirmed that the cultured cells were tenocytes with the majority of the cells having positive stains for mohawk and tenomodulin proteins. The qualities of the degenerative nature of tenocytes were then determined by comparing the cells with the healthy control using a proliferation assay or qRT-PCR. The degenerative tenocyte displayed a higher proliferation rate and similar gene expression patterns of tendinopathy that matched previous reports. Overall, this new protocol might provide a useful tool for future studies of tendinopathy.

In vitro use of degenerative tenocytes is essential when investigating the efficacy of novel treatment on tendinopathy. However, most research studies use only the animal model or a healthy tenocyte. We propose the following protocol to isolate human degenerative tenocytes during surgery.

Tendinopathy, a painful condition that develops in response to tendon degeneration, is on the rise in the developed world due to increasing physical ...

Isometric Contractility Measurement of the Mouse Mesenteric Artery Using Wire Myography

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and drugs. It is widely used in many studies on the physiological functions of vascular smooth muscle, the pathogenesis of vascular diseases such as hypertension, and the development of smooth muscle relaxant drugs. The mouse is a widely used model animal with a large pool of disease models and genetically modified strains. We introduced this method to measure the isometric contraction of mouse mesenteric artery in detail. A 1.4-mm segment of mouse mesenteric resistance artery was isolated and mounted on a myograph chamber by passing two steel wires through its lumen. After equilibration and normalization steps, the vessel segment was potentiated by a high-K+ solution twice prior to the contraction assay. As an example of the application of this method in drug development, we measured the relaxant effect of a novel natural substance, neoliensinine, isolated from a Chinese herb, embryos of the lotus seed (Nelumbo nucifera Gaertn.) on mouse mesenteric arteries. The vessel segments mounted on the myograph chamber were stimulated with a high-K+ solution. When the force tension reached a stable sustained phase, cumulative doses of neoliensinine were added to the chamber. We found that neoliensinine had a dose-dependent relaxant effect on smooth muscle contraction, thus suggesting that it bears potential activity against hypertension. In addition, as the vessel segment can survive at least 4 hours after mounting and maintain contractility induced by the high-K+ solution for many times, we suggest that the wire myograph system may be used for the time-consuming process of drug screening.

The wire myograph technique is used to investigate vascular smooth muscle functions and screen new drugs. We report a detailed protocol for measuring the isometric contractility of the mouse mesenteric artery and for screening new relaxants of vascular smooth muscle.

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and ...

Ex Vivo Corneal Organ Culture Model for Wound Healing Studies

The cornea has been used extensively as a model system to study wound healing. The ability to generate and utilize primary mammalian cells in two dimensional (2D) and three dimensional (3D) culture has generated a wealth of information not only about corneal biology but also about wound healing, myofibroblast biology, and scarring in general. The goal of the protocol is an assay system for quantifying myofibroblast development, which characterizes scarring. We demonstrate a corneal organ culture ex vivo model using pig eyes. In this anterior keratectomy wound, corneas still in the globe are wounded with a circular blade called a trephine. A plug of approximately 1/3 of the anterior cornea is removed including the epithelium, the basement membrane, and the anterior part of the stroma. After wounding, corneas are cut from the globe, mounted on a collagen/agar base, and cultured for two weeks in supplemented-serum free medium with stabilized vitamin C to augment cell proliferation and extracellular matrix secretion by resident fibroblasts. Activation of myofibroblasts in the anterior stroma is evident in the healed cornea. This model can be used to assay wound closure, the development of myofibroblasts and fibrotic markers, and for toxicology studies. In addition, the effects of small molecule inhibitors as well as lipid-mediated siRNA transfection for gene knockdown can be tested in this system.

A protocol for an ex vivo corneal organ culture model useful for wound healing studies is described. This model system can be used to assess the effects of agents to promote regenerative healing or drug toxicity in an organized 3D multicellular environment.

The cornea has been used extensively as a model system to study wound healing. The ability to generate and utilize primary mammalian cells in two ...

A Porcine Corneal Endothelial Organ Culture Model Using Split Corneal Buttons

Experimental research on corneal endothelial cells is associated with several difficulties. Human donor corneas are scarce and rarely available for experimental investigations as they are normally needed for transplantation. Endothelial cell cultures often do not translate well to in vivo situations. Due to the biostructural characteristics of non-human corneas, stromal swelling during cultivation induces substantial corneal endothelial cell loss, which makes it difficult to perform cultivation for an extended period of time. Deswelling agents such as dextran are used to counteract this response. However, they also cause significant endothelial cell loss. Therefore, an ex vivo organ culture model not requiring deswelling agents was established. Pig eyes from a local slaughterhouse were used to prepare split corneal buttons. After partial corneal trephination, the outer layers of the cornea (epithelium, bowman layer, parts of the stroma) were removed. This significantly reduces corneal endothelial cell loss induced by massive stromal swelling and Descemet&#39;s membrane folding throughout longer cultivation periods and improves general preservation of the endothelial cell layer. Subsequent complete corneal trephination was followed by the removal of the split corneal button from the remaining eye bulb and cultivation. Endothelial cell density was assessed at follow-up times of up to 15 days after preparation (i.e., days 1, 8, 15) using light microscopy. The preparation technique used allows a better preservation of the endothelial cell layer enabled by less stromal tissue swelling, which results in slow and linear decline rates in split corneal buttons comparable to human donor corneas. As this standardized organo-typically cultivated research model for the first time allows a stable cultivation for at least two weeks, it is a valuable alternative to human donor corneas for future investigations of various external factors with regards to their effects on the corneal endothelium.

Here, a step-by-step protocol for the preparation and cultivation of porcine split corneal buttons is presented. As this organo-typically cultivated organ culture model shows cell death rates within 15 days, comparable to human donor corneas, it represents the first model allowing long-term cultivation of non-human corneas without adding toxic dextran.

Experimental research on corneal endothelial cells is associated with several difficulties. Human donor corneas are scarce and rarely available for ...

A Rat Lung Transplantation Model of Warm Ischemia/Reperfusion Injury: Optimizations to Improve Outcomes

From our experience with rat lung transplantation, we have found several areas for improvement. Information in the existing literature regarding methods for choosing appropriate cuff sizes for the pulmonary vein (PV), pulmonary artery (PA), or bronchus (Br) are varied, thus making the determination of proper cuff size during rat lung transplantation an exercise of trial and error. By standardizing the cuffing technique to use the smallest effective cuff appropriate for the size of the vessel or bronchus, one can make the transplantation procedure safer, faster, and more successful. Since diameters of the PV, PA, and Br are related to the body weight of the rat, we present a strategy to choosing an appropriate size using a weight-based guide. Since lung volume is also related to body weight, we recommend that this relationship should also be considered when choosing the proper volume of air for donor lung inflation during warm ischemia as well as for the proper volume of PBS to be instilled during bronchoalveolar lavage (BAL) fluid collection. We also describe methods for 4th intercostal space dissection, wound closure, and sample collection from both the native and transplanted lobes.

Here, we present optimizations to a rat lung transplantation model that serve to improve outcomes. We provide a size guide for cuffs based on body weight, a measurement strategy to ascertain the 4th intercostal space, and methods of wound closure and BAL (bronchoalveolar lavage) fluid and tissue collection.

From our experience with rat lung transplantation, we have found several areas for improvement. Information in the existing literature regarding methods ...