The authors thank the study participants who made this research possible and dedicate this report to new scientists in the osteoarthritis field.

This study protocol was approved and followed institutional guidelines set by the Henry Ford Health System Institutional Review Board (IRB #13995).
1. Patient selection
<ol>
	<li>Identify the patients from among those scheduled to undergo TKA with an orthopedic surgeon.</li>
	<li>Select the patients based on the eligibility criteria defined by the study protocol. Examples of inclusion criteria include being 18 years of age or older and having a confirmed diagnosis of knee osteoarthritis. Exa...

<ol>
	<li>Gupton, M., Imonugo, O., Terreberry, R. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Anatomy, Bony Pelvis, and Lover Limb, Knee. , (2020).</li><li>Pacifici, M., Koyama, E., Iwamoto, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanisms+of+Synovial+joint+and+articular+cartilage+formation:+recent+advances,+but+many+lingering+mysteries.">Mechanisms of Synovial joint and articular cartilage formation: recent advances, but many lingering mysteries.</a> Birth Defects Research Part C: Embryo Today: Reviews. 75 (3), 237-248 (2005).</li><li>Gupton, M., Munjal, A., Terreberry, R. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Anatomy, Hinge Joints. , (2020).</li><li>Chen, 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=Osteoarthritis:+Toward+a+comprehensive+understanding+of+pathological+mechanism.">Osteoarthritis: Toward a comprehensive understanding of pathological mechanism.</a> Bone Research. 5, 16044 (2017).</li><li>Murphy, 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=Lifetime+risk+of+symptomatic+knee+osteoarthritis.">Lifetime risk of symptomatic knee osteoarthritis.</a> Arthritis &amp; Rheumatism. 59 (9), 1207-1213 (2008).</li><li>O'Neill, T. W., McCabe, P. S., McBeth, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Update+on+the+epidemiology,+risk+factors+and+disease+outcomes+of+osteoarthritis.">Update on the epidemiology, risk factors and disease outcomes of osteoarthritis.</a> Best Practice &amp; Research: Clinical Anaesthesiology. 32 (2), 312-326 (2018).</li><li>Nguyen, U. 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=Increasing+prevalence+of+knee+pain+and+symptomatic+knee+osteoarthritis:+survey+and+cohort+data.">Increasing prevalence of knee pain and symptomatic knee osteoarthritis: survey and cohort data.</a> Annals of Internal Medicine. 155 (11), 725-732 (2011).</li><li>Deshpande, B. R., 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=Number+of+persons+with+symptomatic+knee+osteoarthritis+in+the+us:+impact+of+race+and+ethnicity,+age,+sex,+and+obesity.">Number of persons with symptomatic knee osteoarthritis in the us: impact of race and ethnicity, age, sex, and obesity.</a> Arthritis Care &amp; Research. 68 (12), 1743-1750 (2016).</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 &amp; Rheumatism. 64 (6), 1697-1707 (2012).</li><li>McGonagle, D., Tan, A. L., Carey, J., Benjamin, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+anatomical+basis+for+a+novel+classification+of+osteoarthritis+and+allied+disorders.">The anatomical basis for a novel classification of osteoarthritis and allied disorders.</a> Journal of Anatomy. 216 (3), 279-291 (2010).</li><li>Bannuru, R. R., 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=OARSI+guidelines+for+the+non-surgical+management+of+knee,+hip,+and+polyarticular+osteoarthritis.">OARSI guidelines for the non-surgical management of knee, hip, and polyarticular osteoarthritis.</a> Osteoarthritis Cartilage. 27 (11), 1578-1589 (2019).</li><li>Kolasinski, S. 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=American+College+of+Rheumatology/Arthritis+Foundation+Guideline+for+the+Management+of+Osteoarthritis+of+the+Hand,+Hip,+and+knee.">American College of Rheumatology/Arthritis Foundation Guideline for the Management of Osteoarthritis of the Hand, Hip, and knee.</a> Arthritis Care &amp; Research. 72 (2), 220-233 (2020).</li><li>Michael, J. W., Schluter-Brust, K. U., Eysel, 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+epidemiology,+etiology,+diagnosis,+and+treatment+of+osteoarthritis+of+the+knee.">The epidemiology, etiology, diagnosis, and treatment of osteoarthritis of the knee.</a> Deutsches &#196;rzteblatt International. 107 (9), 152-162 (2010).</li><li>Singh, J. A., Yu, S., Chen, L., Cleveland, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rates+of+total+joint+replacement+in+the+United+States:+Future+projections+to+2020-2040+using+the+national+inpatient+sample.">Rates of total joint replacement in the United States: Future projections to 2020-2040 using the national inpatient sample.</a> Journal of Rheumatology. 46 (9), 1134-1140 (2019).</li><li>Gemayel, A. C., Varacallo, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Total+Knee+Replacement+Techniques.">Total Knee Replacement Techniques.</a> StatPearls. , (2020).</li><li>Shan, L., Shan, B., Suzuki, A., Nouh, F., Saxena, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intermediate+and+long-term+quality+of+life+after+total+knee+replacement:+a+systematic+review+and+meta-analysis.">Intermediate and long-term quality of life after total knee replacement: a systematic review and meta-analysis.</a> Journal of Bone and Joint Surgery (American Volume). 97 (2), 156-168 (2015).</li><li>Newton, P. 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=Chondrogenic+Atdc5+cells:+an+optimised+model+for+rapid+and+physiological+matrix+mineralisation.">Chondrogenic Atdc5 cells: an optimised model for rapid and physiological matrix mineralisation.</a> International Journal of Molecular Medicine. 30 (5), 1187-1193 (2012).</li><li>Chuang, Y. W., 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=Lysophosphatidic+acid+enhanced+the+angiogenic+capability+of+human+chondrocytes+by+regulating+Gi/Nf-Kb-dependent+angiogenic+factor+expression.">Lysophosphatidic acid enhanced the angiogenic capability of human chondrocytes by regulating Gi/Nf-Kb-dependent angiogenic factor expression.</a> PLoS One. 9 (5), 95180 (2014).</li><li>Johnson, C. I., Argyle, D. J., Clements, D. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+models+for+the+study+of+osteoarthritis.">In vitro models for the study of osteoarthritis.</a> Veterinary Journal. 209, 40-49 (2016).</li><li>Grivel, J. C., Margolis, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Use+of+human+tissue+explants+to+study+human+infectious+agents.">Use of human tissue explants to study human infectious agents.</a> Nature Protocols. 4 (2), 256-269 (2009).</li><li>Glasson, S. S., Blanchet, T. J., Morris, E. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+surgical+destabilization+of+the+medial+meniscus+(dmm)+model+of+osteoarthritis+in+the+129/Svev+mouse.">The surgical destabilization of the medial meniscus (dmm) model of osteoarthritis in the 129/Svev mouse.</a> Osteoarthritis Cartilage. 15 (9), 1061-1069 (2007).</li><li>McIlwraith, C. W., Frisbie, D. D., Kawcak, C. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+horse+as+a+model+of+naturally+occurring+osteoarthritis.">The horse as a model of naturally occurring osteoarthritis.</a> Bone &amp; Joint Research. 1 (11), 297-309 (2012).</li><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 Cartilage. 27 (2), 230-239 (2019).</li><li>Goldenberg, A. 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=IRB+practices+and+policies+regarding+the+secondary+research+use+of+biospecimens.">IRB practices and policies regarding the secondary research use of biospecimens.</a> Bmc Medical Ethics. 16, 32 (2015).</li><li>Ruettger, A., Neumann, S., Wiederanders, B., Huber, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+different+methods+for+preparation+and+characterization+of+total+rna+from+cartilage+samples+to+uncover+osteoarthritis+in+vivo.">Comparison of different methods for preparation and characterization of total rna from cartilage samples to uncover osteoarthritis in vivo.</a> BMC Research Notes. 3, 7 (2010).</li><li>Reno, C., Marchuk, L., Sciore, P., Frank, C. B., Hart, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+isolation+of+total+RNA+from+small+samples+of+hypocellular,+dense+connective+tissues.">Rapid isolation of total RNA from small samples of hypocellular, dense connective tissues.</a> BioTechniques. 22 (6), 1082-1086 (1997).</li><li>Fox, A. J., Bedi, A., Rodeo, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+basic+science+of+human+knee+menisci:+structure,+composition,+and+function.">The basic science of human knee menisci: structure, composition, and function.</a> Sports Health. 4 (4), 340-351 (2012).</li><li>Carballo, C. B., Nakagawa, Y., Sekiya, I., Rodeo, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Basic+science+of+articular+cartilage.">Basic science of articular cartilage.</a> Clinics in Sports Medicine. 36 (3), 413-425 (2017).</li><li>Le Bleu, H. 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=Extraction+of+high-quality+RNA+from+human+articular+cartilage.">Extraction of high-quality RNA from human articular cartilage.</a> Analytical Biochemistry. 518, 134-138 (2017).</li><li>Ali, S. A., Alman, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RNA+extraction+from+human+articular+cartilage+by+chondrocyte+isolation.">RNA extraction from human articular cartilage by chondrocyte isolation.</a> Analytical Biochemistry. 429 (1), 39-41 (2012).</li><li>Schroeder, 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+Rin:+An+RNA+integrity+number+for+assigning+integrity+values+to+rna+measurements.">The Rin: An RNA integrity number for assigning integrity values to rna measurements.</a> BMC Molecular Biology. 7, 3 (2006).</li><li>Li, 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=Multi-platform+assessment+of+transcriptome+profiling+using+RNA-seq+in+the+abrf+next-generation+sequencing+study.">Multi-platform assessment of transcriptome profiling using RNA-seq in the abrf next-generation sequencing study.</a> Nature Biotechnology. 32 (9), 915-925 (2014).</li><li>Nazarov, P. 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=RNA+sequencing+and+transcriptome+arrays+analyses+show+opposing+results+for+alternative+splicing+in+patient+derived+samples.">RNA sequencing and transcriptome arrays analyses show opposing results for alternative splicing in patient derived samples.</a> BMC Genomics. 18 (1), 443 (2017).</li><li>Madissoon, 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=scRNA-seq+assessment+of+the+human+lung,+spleen,+and+esophagus+tissue+stability+after+cold+preservation.">scRNA-seq assessment of the human lung, spleen, and esophagus tissue stability after cold preservation.</a> Genome Biology. 21 (1), (2019).</li><li>Scholes, A. N., Lewis, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+RNA+isolation+methods+on+RNA-seq:+implications+for+differential+expression+and+meta-analyses.">Comparison of RNA isolation methods on RNA-seq: implications for differential expression and meta-analyses.</a> BMC Genomics. 21 (1), 249 (2020).</li><li>Smith, M. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+normal+synovium.">The normal synovium.</a> Open Rheumatology Journal. 5, 100-106 (2011).</li><li>Kukurba, K. R., Montgomery, S. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RNA+sequencing+and+analysis.">RNA sequencing and analysis.</a> Cold Spring Harbor Protocols. 2015 (11), 951-969 (2015).</li><li>Mobasheri, A., Kapoor, M., Ali, S. 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The protocol presented has proved successful for collecting seven primary human OA tissues for RNA extraction (Table 1) and histological processing (Figure 4). Prior to collecting patient samples, it is necessary to establish an IRB-approved protocol, ideally in collaboration with a surgeon or surgical team. Applying a standardized protocol for specimen collection (e.g., resection from consistent in situ locations) is essential for maximizing experimental reproducib...

The knee is the largest synovial joint in the human body, comprising the tibiofemoral joint between the tibia and the femur and the patellofemoral joint between the patella and the femur1. The bones in the knee are lined with articular cartilage and supported by various connective tissues, including menisci, fat, ligaments, and muscle, and a synovial membrane encapsulates the whole joint to create a synovial fluid-filled cavity1,2,3 (Figure 1). A healthy knee functions as a mobile hinge joint that allows frictionless motion in the frontal plane1,3. Under pathological conditions, movement can become restricted and painful. The most common degenerative knee joint disease is osteoarthritis (OA)4. A variety of risk factors are known to predispose to OA development, including older age, obesity, female sex, joint trauma, and genetics, among others5,6. There are currently an estimated 14 million people in the USA with symptomatic knee OA, with the prevalence increasing due to rising population age and rates of obesity7,8. Initially considered to be a disease of the cartilage, OA is now understood as a disease of the whole joint9. Commonly observed pathological changes in OA include articular cartilage erosion, osteophyte formation, subchondral bone thickening, and inflammation of the synovium9,10. Since there is no known cure for OA, treatments primarily focus on symptom (e.g., pain) management11,12, and once OA has progressed to end-stage, joint replacement surgery is often indicated13.
Joint replacement surgeries can either be partial or total knee replacements, with total knee arthroplasty (TKA) including replacing the entire tibiofemoral articulation and the patellofemoral joint. As of 2020, approximately 1 million TKAs are performed in the USA each year14. During TKA, an orthopedic surgeon resects the upper portion of the tibial plateau and the lower femoral condyles (Figure 2A, 2B) to be fitted with prosthetic implants. Sometimes misinterpreted by patients, in a TKA, only 8-10 mm is resected from the end of each bone, which is subsequently capped or resurfaced, with metal. An interposed polyethylene liner forms the bearing surface (i.e., padding) between the two metal implants. In addition, several soft tissue components of the joint are fully or partially excised to achieve proper joint balance. Among these tissues are the medial and lateral menisci (Figure 2C), infrapatellar fat pad (Figure 2D), anterior cruciate ligament (ACL; Figure 2E), synovium (Figure 2F), and vastus medialis oblique muscle (VMO; Figure 2G)15. Though TKAs are generally successful for OA treatment, around 20% of patients report reoccurrence of pain post-surgery16. Along with the high cost and relative invasiveness of the procedure, these limitations point to the need for further research to identify alternative treatments to mitigate the progression of OA.
To explore disease mechanisms in OA that may present new avenues for therapeutic intervention, experimental systems, including cells, tissue explants, and animal models can be used. Cells are typically cultured in monolayer and are derived from primary human or animal tissues (e.g., chondrocytes isolated from cartilage) or immortalized cells (e.g., ATDC517 and CHON-00118). While cells can be useful for manipulating experimental variables in a controlled culture environment, they do not capture conditions of the natural joint which are known to impact cell phenotypes19. To better recapitulate the complex cascade of chemical, mechanical, and cell-to-cell communication underlying OA, an alternative is found in primary human or animal tissue samples, whether used fresh or cultured ex vivo as explants, to preserve tissue structure and the cell microenvironment20. In order to study the joint in vivo, small (e.g., mouse21) and large (e.g., horse22) animal models for OA (e.g., through surgical induction, genetic alteration, or aging) are also useful. However, translation from these models to human disease can be limited by anatomical, physiological, and metabolic differences, among others23. Considering the advantages and disadvantages of experimental systems, the key strengths of being species-specific and maintaining the extracellular niche offered by the primary human OA tissues maximize the translational potential of research findings.
Primary human OA tissues can be readily obtained following TKA, making the high frequency of TKAs a valuable resource for research. Among potential experimental applications are gene expression and histological analyses. To realize the potential of primary human OA tissues for these research approaches and others, outlined are the following key considerations. First, the use of patient specimens is subject to ethical regulation, and protocols must meet Institutional Review Board (IRB) approvals24. Second, the inherent heterogeneity of human primary diseased tissues and the influence of variables such as age and sex, among others, create the need for careful patient selection (i.e., application of eligibility criteria) and data interpretation. Third, the unique biological properties of different tissues in the joint (e.g., low cellularity of cartilage and meniscus25) can present challenges during experiments (e.g., isolating high quality and quantity of RNA). This report addresses these considerations and presents a protocol for patient selection, sample processing, tissue homogenization, RNA extraction, and quality control (i.e., assessment of RNA purity and integrity; Figure 3) to encourage the use of primary human OA tissues in the research community.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>1.5 mL microcentrifuge tubes</td>
			<td>Eppendorf</td>
			<td>05 402</td>
			<td>Sterile, nuclease-free. Reserved for RNA work only.</td>
		</tr>
		<tr>
			<td>10% Formalin</td>
			<td>Cardinal Health</td>
			<td>C4320-101</td>
			<td>Store in chemical cabinet when not in use.</td>
		</tr>
		<tr>
			<td>100% Chloroform (Molecular Biology Grade)</td>
			<td>Fisher Scientific</td>
			<td>ICN19400290</td>
			<td>Sterile, nuclease-free. Reserved for RNA work only, store in chemical cabinet when not in use.</td>
		</tr>
		<tr>
			<td>100% Ethanol (Molecular Biology Grade)</td>
			<td>Fisher Scientific</td>
			<td>BP2818500</td>
			<td>Sterile, nuclease-free. Reserved for RNA work only, when diluting use DEPC/nuclease-free water.</td>
		</tr>
		<tr>
			<td>100% Isopropanol (Molecular Biology Grade)</td>
			<td>Fisher Scientific</td>
			<td>AC327272500</td>
			<td>Sterile, nuclease-free. Reserved for RNA work only, store in chemical cabinet when not in use.</td>
		</tr>
		<tr>
			<td>100% Reagent Alcohol</td>
			<td>Cardinal Health</td>
			<td>C4305</td>
			<td>Diluted to 70% with dH2O for cleaning purposes.</td>
		</tr>
		<tr>
			<td>15 cm sterile culture dishes</td>
			<td>Thermo Scientific</td>
			<td>12-556-003</td>
			<td>Sterile, nuclease-free.</td>
		</tr>
		<tr>
			<td>15 mL polypropylene (Falcon) tubes</td>
			<td>Fisher Scientific</td>
			<td>14 959 53A</td>
			<td>Sterile, nuclease-free.</td>
		</tr>
		<tr>
			<td>2 mL cryovials (externally threaded)</td>
			<td>Fisher Scientific</td>
			<td>10 500 26</td>
			<td>Sterile, nuclease-free.</td>
		</tr>
		<tr>
			<td>5 mL round-bottom tubes</td>
			<td>Corning</td>
			<td>352052</td>
			<td>Sterile, nuclease-free. Reserved for RNA work only.</td>
		</tr>
		<tr>
			<td>50 mL polypropylene (Falcon) tubes</td>
			<td>Fisher Scientific</td>
			<td>12 565 271</td>
			<td>Sterile, nuclease-free.</td>
		</tr>
		<tr>
			<td>Bioanalyzer</td>
			<td>Agilent</td>
			<td>G2939BA</td>
			<td>For RNA integrity measurement.</td>
		</tr>
		<tr>
			<td>Biosafety Cabinet</td>
			<td colspan="2">General lab equipment</td>
			<td></td>
		</tr>
		<tr>
			<td>Bone Cutters</td>
			<td>Fisher Scientific</td>
			<td>08 990</td>
			<td>Sterilized with 70% EtOH.</td>
		</tr>
		<tr>
			<td>Chemical Fume Hood</td>
			<td colspan="2">General lab equipment</td>
			<td></td>
		</tr>
		<tr>
			<td>Disposable Scalpels (No.10)</td>
			<td>Thermo Scientific</td>
			<td>3120032</td>
			<td>Sterile, nuclease-free.</td>
		</tr>
		<tr>
			<td>EDTA</td>
			<td>Life Technologies</td>
			<td>15-576-028</td>
			<td>10% solution with dH2O.</td>
		</tr>
		<tr>
			<td>Forceps</td>
			<td>Any vendor</td>
			<td></td>
			<td>Sterilized with 70% EtOH.</td>
		</tr>
		<tr>
			<td>Glycoblue Coprecipitant</td>
			<td>Fisher Scientific</td>
			<td>AM9516</td>
			<td>Reserved for RNA work only, store at -20 &#176;C.</td>
		</tr>
		<tr>
			<td>Kimwipes</td>
			<td>Fisher Scientific</td>
			<td>06-666</td>
			<td></td>
		</tr>
		<tr>
			<td>Liquid Nitrogen</td>
			<td>Any vendor</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Liquid Nitrogen Dewar</td>
			<td colspan="2">General lab equipment</td>
			<td></td>
		</tr>
		<tr>
			<td>Mortar and Pestle</td>
			<td>Any vendor</td>
			<td></td>
			<td>Reserved for RNA work only, sterilzed per protocol.</td>
		</tr>
		<tr>
			<td>Nanodrop Spectrophotometer</td>
			<td>Thermo Scientific</td>
			<td>ND-2000</td>
			<td>For RNA purity and yield measurements.</td>
		</tr>
		<tr>
			<td>Nuclease-free/DEPC-treated water</td>
			<td>Fisher Scientific</td>
			<td></td>
			<td>Sterile, nuclease-free. Reserved for RNA work only.</td>
		</tr>
		<tr>
			<td>PBS (Sterile)</td>
			<td>Gibco</td>
			<td>20 012 050</td>
			<td>Sterile, nuclease-free.</td>
		</tr>
		<tr>
			<td>Pipettes (2 &#181;L, 20 &#181;L, 200 &#181;L, 1000 &#181;L) &#38; tips</td>
			<td>Any vendor</td>
			<td></td>
			<td>Sterile, nuclease-free.</td>
		</tr>
		<tr>
			<td>Plasma/Serum Advanced miRNA kit</td>
			<td>Qiagen</td>
			<td>217204</td>
			<td></td>
		</tr>
		<tr>
			<td>Refrigerated Centrifuge 5810R</td>
			<td>Eppendorf</td>
			<td>22625101</td>
			<td></td>
		</tr>
		<tr>
			<td>RNAlater</td>
			<td>Thermo Scientific</td>
			<td>50 197 8158</td>
			<td>Sterile, nuclease-free.</td>
		</tr>
		<tr>
			<td>RNAse Away/RNAseZap</td>
			<td>Fisher Scientific</td>
			<td> 
			7002</td>
			<td></td>
		</tr>
		<tr>
			<td>Spatula (semimicro size)</td>
			<td>Any vendor</td>
			<td></td>
			<td>Reserved for RNA work only.</td>
		</tr>
		<tr>
			<td>Tissue homogenizer</td>
			<td>Pro Scientific</td>
			<td>01-01200</td>
			<td>Reserved for RNA work only, sterilzed per protocol.</td>
		</tr>
		<tr>
			<td>TRIzol Reagent</td>
			<td>Fisher Scientific</td>
			<td>15 596 026</td>
			<td>Sterile, nuclease-free. Reserved for RNA work only.</td>
		</tr>
	</tbody>
</table>

tissue collection and rna extraction from the human osteoarthritic knee joint

Osteoarthritis (OA) is a chronic and degenerative joint disease most often affecting the knee. As there is currently no cure, total knee arthroplasty (TKA) is a common surgical intervention. Experiments using primary human OA tissues obtained from TKA provide the capability to investigate disease mechanisms ex vivo. While OA was previously thought to impact mainly the cartilage, it is now known to impact multiple tissues in the joint. This protocol describes patient selection, sample processing, tissue homogenization, RNA extraction, and quality control (based on RNA purity, integrity, and yield) from each of seven unique tissues to support disease mechanism investigation in the knee joint. With informed consent, samples were obtained from patients undergoing TKA for OA. Tissues were dissected, washed, and stored within 4 h of surgery by flash freezing for RNA or formalin fixation for histology. Collected tissues included articular cartilage, subchondral bone, meniscus, infrapatellar fat pad, anterior cruciate ligament, synovium, and vastus medialis oblique muscle. RNA extraction protocols were tested for each tissue type. The most significant modification involved the method of disintegration used for low-cell, high-matrix, hard tissues (considered as cartilage, bone, and meniscus) versus relatively high-cell, low-matrix, soft tissues (considered as fat pad, ligament, synovium, and muscle). It was found that pulverization was appropriate for hard tissues, and homogenization was appropriate for soft tissues. A proclivity for some subjects to yield higher RNA integrity number (RIN) values than other subjects consistently across multiple tissues was observed, suggesting that underlying factors such as disease severity may impact RNA quality. The ability to isolate high-quality RNA from primary human OA tissues provides a physiologically relevant model for sophisticated gene expression experiments, including sequencing, that can lead to clinical insights that are more readily translated to patients.

Seven unique human knee joint tissues are available for collection from patients undergoing TKA for OA (Figure 1). In this protocol, each of these tissues were identified and processed within 4 h of surgical removal (Figure 2). Following the steps outlined in Figure 3, portions of each tissue were formalin-fixed for histological assessment (Figure 4), while other portions were flash-frozen for RNA isola...

Watch this Scientific Journal Video about Tissue Collection and RNA Extraction from the Human Osteoarthritic Knee Joint at JoVE.com

Tissue Collection and RNA Extraction from the Human Osteoarthritic Knee Joint

Primary tissues obtained from patients following total knee arthroplasty provide an experimental model for osteoarthritis research with maximal clinical translatability. This protocol describes how to identify, process, and isolate RNA from seven unique knee tissues to support mechanistic investigation in human osteoarthritis.

Osteoarthritis (OA) is a chronic and degenerative joint disease most often affecting the knee. As there is currently no cure, total knee arthroplasty ...

This protocol encourages the use of primary human tissues as a clinically relevant model for osteoarthritis research. Performing gene expression and histological analyses in these tissues may provide novel mechanistic insights. This technique standardizes methods for the identification and processing of human knee joint components.It enables the extraction of high quality RNA that meets the requirements for downstream gene expression assays. It is challenging to obtain high quality RNA from diseased joint tissues, so the importance of seemingly insignificant steps, such as keeping everything clean and cool should not be underestimated. Demonstrating the procedure will be Thomas Wilson, a research associate and Navdeep Kaur, a postdoctoral fellow from my laboratory.Begin by identifying the hard tissues, including cartilage, bone, and meniscus and soft tissues, including infrapatellar fat pad, anterior cruciate ligament, synovium and vastus medialis oblique muscle from the specimen based on the differences in the size, shape, color and texture. Cut each of the tissues into three sections. Rinse the tissue sections with sterile PBS to remove any residue or debris.For RNA extraction, cut each of the three tissue sections into approximately one to two millimeter cubes. Transfer the smaller pieces to a two milliliter cryo vial. After securing the caps tightly, flash freeze the vials by submerging in liquid nitrogen for 30 seconds, then transfer the vial to the minus 80 degrees Celsius freezer for long-term storage, and repeat this procedure for all the tissues.Homogenize the hard tissue using a mortar and pestle. Before homogenization, chill the mortar, pestle and spatula using liquid nitrogen to prevent the sample from thawing. Process only one sample at a time.Transfer the tissue sample to mortar using a chilled spatula. Pour liquid nitrogen on top of the tissue. After the liquid nitrogen evaporates, crush the tissue with a pestle.Repeatedly add liquid nitrogen while grinding the tissue to obtain fine tissue powder. Transfer the fine tissue powder in a 1.5 milliliter micro centrifuge tube pre-chilled by submerging in liquid nitrogen for 30 seconds. Add one milliliter of the ice-cold acid guanidinium phenol solution to each tube and incubate the tubes on ice for 20 minutes.Before homogenizing different hard tissue, thoroughly clean the mortar, pestle and spatula with 70%ethanol, then with RNase decontaminant, followed by DEPC treated water. Soak the mortar, pestle and spatula in 70%ethanol, then wipe any residual liquid with a clean, lint-free tissue. Homogenize the soft tissue using the tissue homogenizer.For disinfecting the homogenizer, wash the probe by running tubes of 70%ethanol and RNase decontaminant for 30 seconds per wash, then wash with DEPC treated water, followed by an additional 70%ethanol, each for 30 seconds. Wipe any residual liquid with a clean, lint-free tissue. Add one milliliter of acid guanidinium phenol solution to pre-labeled, five milliliter round bottom tubes, and transfer the tissue sample into the tube.Place the tube on ice throughout the procedure and homogenize the tissue for a maximum of five 32nd pulses, or until the tissue is visually dissolved. Incubate the homogenized tissue on ice until all the tissue samples are processed. Disinfect and clean the homogenizer before processing the next tissue sample.Using sterile forceps, remove any tissue chunk present in the teeth of the probe. Incubate all the homogenized tissue on the ice for additional 20 minutes and then transfer the tissue sample to a pre-labeled, pre-chilled 1.5 milliliter micro centrifuge tube. Seven unique human knee joint tissues obtained from osteoarthritis patients were processed within four hours of surgical removal.The tissues were identified visually and confirmed by H&E histological staining. The H&E stained hard tissue sections, articular cartilage, subchondral bone and meniscus were visualized at six times magnification and 40 times magnification. Similarly, the H&E stained soft tissue sections, infrapatellar fat pad, anterior cruciate ligament, synovium and vastus medialis oblique muscle were visualized at six times magnification and then at 40 times magnification.The quality assessment of extracted RNA indicated the presence of high quality samples based on integrity, yield and purity, as well as low quality samples, suggesting that despite using an optimized method, external factors like disease severity may impact the RNA quality across different tissues from the same patient. Correct identification of each tissue type is necessary to enable intra-and inter-tissue comparisons within and across patient samples, especially given the considerable heterogeneity of primary disease tissues. Sequencing technologies are rapidly evolving, and isolation of high quality RNA is a critical prerequisite to using these technologies to unravel underlying tissue-specific mechanisms in complex, chronic diseases like osteoarthritis.

tissue-collection-rna-extraction-from-human-osteoarthritic-knee

Research

JoVE Journal

Biology

5.5K vistas.  Henry Ford Health System. Este protocolo fomenta el uso de tejidos humanos primarios como un modelo clínicamente relevante para la investigación de la osteoartritis. La realización de análisis histológicos y de expresión génica en estos tejidos puede proporcionar nuevos conocimientos mecanicistas. Esta técnica estandariza los métodos para la identificación y el procesamiento de los componentes de la articulación de la rodilla humana.Permite la extracción de ARN de alta calidad que cumple con los req...