Research reported in this publication was supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases, part of the National Institutes of Health, under Award Number R01 AR075013.

All procedures described have been approved by the Institutional Animal Care and Use Committee at the University of California Davis. 3-month-old male C57BL/6J mice were used for the present study.
1. Non-invasive ACL injury
NOTE: ACL injury produced by an externally applied compressive load is a simple and reproducible method that closely recapitulates ACL injury conditions in humans. This protocol is written for a commercially available load frame i...

Impact of Non-Invasive ACL Injury and Surgery on Protease Activity in Mice

<ol>
	<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 (Hoboken. 68 (12), 1743-1750 (2016).</li><li>Carbone, A., Rodeo, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Review+of+current+understanding+of+post-traumatic+osteoarthritis+resulting+from+sports+injuries.">Review of current understanding of post-traumatic osteoarthritis resulting from sports injuries.</a> Journal of Orthopaedic Research. 35 (3), 397-405 (2017).</li><li>Thomas, A. C., Hubbard-Turner, T., Wikstrom, E. A., Palmieri-Smith, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epidemiology+of+posttraumatic+osteoarthritis.">Epidemiology of posttraumatic osteoarthritis.</a> Journal of Athletic Training. 52 (6), 491-496 (2017).</li><li>Wang, L. J., Zeng, N., Yan, Z. P., Li, J. T., Ni, G. X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Post-traumatic+osteoarthritis+following+ACL+injury.">Post-traumatic osteoarthritis following ACL injury.</a> Arthritis Research &amp; Therapy. 22 (1), 57 (2020).</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>Kamekura, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Osteoarthritis+development+in+novel+experimental+mouse+models+induced+by+knee+joint+instability.">Osteoarthritis development in novel experimental mouse models induced by knee joint instability.</a> Osteoarthritis Cartilage. 13 (7), 632-641 (2005).</li><li>Ma, H. 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=Osteoarthritis+severity+is+sex+dependent+in+a+surgical+mouse+model.">Osteoarthritis severity is sex dependent in a surgical mouse model.</a> Osteoarthritis Cartilage. 15 (6), 695-700 (2007).</li><li>Malfait, A. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ADAMTS-5+deficient+mice+do+not+develop+mechanical+allodynia+associated+with+osteoarthritis+following+medial+meniscal+destabilization.">ADAMTS-5 deficient mice do not develop mechanical allodynia associated with osteoarthritis following medial meniscal destabilization.</a> Osteoarthritis Cartilage. 18 (4), 572-580 (2010).</li><li>Yang, 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=Hypoxia-inducible+factor-2alpha+is+a+catabolic+regulator+of+osteoarthritic+cartilage+destruction.">Hypoxia-inducible factor-2alpha is a catabolic regulator of osteoarthritic cartilage destruction.</a> Nature Medicine. 16 (6), 687-693 (2010).</li><li>Moodie, J. P., Stok, K. S., Muller, R., Vincent, T. L., Shefelbine, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multimodal+imaging+demonstrates+concomitant+changes+in+bone+and+cartilage+after+destabilisation+of+the+medial+meniscus+and+increased+joint+laxity.">Multimodal imaging demonstrates concomitant changes in bone and cartilage after destabilisation of the medial meniscus and increased joint laxity.</a> Osteoarthritis Cartilage. 19 (2), 163-170 (2011).</li><li>Li, 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=Knockout+of+ADAMTS5+does+not+eliminate+cartilage+aggrecanase+activity+but+abrogates+joint+fibrosis+and+promotes+cartilage+aggrecan+deposition+in+murine+osteoarthritis+models.">Knockout of ADAMTS5 does not eliminate cartilage aggrecanase activity but abrogates joint fibrosis and promotes cartilage aggrecan deposition in murine osteoarthritis models.</a> Journal of Orthopaedic Research. 29 (4), 516-522 (2011).</li><li>Shapiro, F., Glimcher, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Induction+of+osteoarthrosis+in+the+rabbit+knee+joint.">Induction of osteoarthrosis in the rabbit knee joint.</a> Clinical Orthopaedics and Related Research. 147, 287-295 (1980).</li><li>Meacock, S. C., Bodmer, J. L., Billingham, M. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+osteoarthritis+in+guinea-pigs.">Experimental osteoarthritis in guinea-pigs.</a> Journal of Experimental Pathology (Oxford). 71 (2), 279-293 (1990).</li><li>Armstrong, S. J., Read, R. A., Ghosh, P., Wilson, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Moderate+exercise+exacerbates+the+osteoarthritic+lesions+produced+in+cartilage+by+meniscectomy:+a+morphological+study.">Moderate exercise exacerbates the osteoarthritic lesions produced in cartilage by meniscectomy: a morphological study.</a> Osteoarthritis Cartilage. 1 (2), 89-96 (1993).</li><li>Pastoureau, P., Leduc, S., Chomel, A., De Ceuninck, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+assessment+of+articular+cartilage+and+subchondral+bone+histology+in+the+meniscectomized+guinea+pig+model+of+osteoarthritis.">Quantitative assessment of articular cartilage and subchondral bone histology in the meniscectomized guinea pig model of osteoarthritis.</a> Osteoarthritis Cartilage. 11 (6), 412-423 (2003).</li><li>Wancket, L. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anatomical+localization+of+cartilage+degradation+markers+in+a+surgically+induced+rat+osteoarthritis+model.">Anatomical localization of cartilage degradation markers in a surgically induced rat osteoarthritis model.</a> Toxicologic Pathology. 33 (4), 484-489 (2005).</li><li>Karahan, S., Kincaid, S. A., Kammermann, J. R., Wright, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+the+rat+stifle+joint+after+transection+of+the+cranial+cruciate+ligament+and+partial+medial+meniscectomy.">Evaluation of the rat stifle joint after transection of the cranial cruciate ligament and partial medial meniscectomy.</a> Comparative Medicine. 51 (6), 504-512 (2001).</li><li>Kamekura, 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=Osteoarthritis+development+in+novel+experimental+mouse+models+induced+by+knee+joint+instability.">Osteoarthritis development in novel experimental mouse models induced by knee joint instability.</a> Osteoarthritis and cartilage / OARS, Osteoarthritis Research Society. 13 (7), 632-641 (2005).</li><li>Jones, M. 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=In+vivo+microfocal+computed+tomography+and+micro-magnetic+resonance+imaging+evaluation+of+antiresorptive+and+antiinflammatory+drugs+as+preventive+treatments+of+osteoarthritis+in+the+rat.">In vivo microfocal computed tomography and micro-magnetic resonance imaging evaluation of antiresorptive and antiinflammatory drugs as preventive treatments of osteoarthritis in the rat.</a> Arthritis &amp; Rheumatology. 62 (9), 2726-2735 (2010).</li><li>Christiansen, B. 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=Non-invasive+mouse+models+of+post-traumatic+osteoarthritis.">Non-invasive mouse models of post-traumatic osteoarthritis.</a> Osteoarthritis Cartilage. 23 (10), 1627-1638 (2015).</li><li>Christiansen, B. 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=Musculoskeletal+changes+following+non-invasive+knee+injury+using+a+novel+mouse+model+of+post-traumatic+osteoarthritis.">Musculoskeletal changes following non-invasive knee injury using a novel mouse model of post-traumatic osteoarthritis.</a> Osteoarthritis Cartilage. 20 (7), 773-782 (2012).</li><li>Lockwood, K. A., Chu, B. T., Anderson, M. J., Haudenschild, D. R., Christiansen, B. 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+loading+rate-dependent+injury+modes+in+a+murine+model+of+post-traumatic+osteoarthritis.">Comparison of loading rate-dependent injury modes in a murine model of post-traumatic osteoarthritis.</a> Journal of Orthopaedic Research. 32 (1), 79-88 (2014).</li><li>Satkunananthan, P. 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=In+vivo+fluorescence+reflectance+imaging+of+protease+activity+in+a+mouse+model+of+post-traumatic+osteoarthritis.">In vivo fluorescence reflectance imaging of protease activity in a mouse model of post-traumatic osteoarthritis.</a> Osteoarthritis Cartilage. 22 (10), 1461-1469 (2014).</li><li>Hsia, A. 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=Post-traumatic+osteoarthritis+progression+is+diminished+by+early+mechanical+unloading+and+anti-inflammatory+treatment+in+mice.">Post-traumatic osteoarthritis progression is diminished by early mechanical unloading and anti-inflammatory treatment in mice.</a> Osteoarthritis Cartilage. 29 (12), 1709-1719 (2021).</li><li>Zhang, H., 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=Biochromoendoscopy:+molecular+imaging+with+capsule+endoscopy+for+detection+of+adenomas+of+the+GI+tract.">Biochromoendoscopy: molecular imaging with capsule endoscopy for detection of adenomas of the GI tract.</a> Gastrointestinal Endoscopy. 68 (3), 520-527 (2008).</li><li>Gounaris, 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=Live+imaging+of+cysteine-cathepsin+activity+reveals+dynamics+of+focal+inflammation,+angiogenesis,+and+polyp+growth.">Live imaging of cysteine-cathepsin activity reveals dynamics of focal inflammation, angiogenesis, and polyp growth.</a> PLoS One. 3 (8), e2916 (2008).</li><li>Sheth, R. A., Mahmood, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+molecular+imaging+and+its+emerging+role+in+colorectal+cancer.">Optical molecular imaging and its emerging role in colorectal cancer.</a> American Journal of Physiology-Gastrointestinal and Liver Physiology. 299 (4), G807-G820 (2010).</li><li>Clapper, M. 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=Detection+of+colorectal+adenomas+using+a+bioactivatable+probe+specific+for+matrix+metalloproteinase+activity.">Detection of colorectal adenomas using a bioactivatable probe specific for matrix metalloproteinase activity.</a> Neoplasia. 13 (8), 685-691 (2011).</li><li>Nahrendorf, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dual+channel+optical+tomographic+imaging+of+leukocyte+recruitment+and+protease+activity+in+the+healing+myocardial+infarct.">Dual channel optical tomographic imaging of leukocyte recruitment and protease activity in the healing myocardial infarct.</a> Circulation Research. 100 (8), 1218-1225 (2007).</li><li>Jaffer, F. 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=Optical+visualization+of+cathepsin+K+activity+in+atherosclerosis+with+a+novel,+protease-activatable+fluorescence+sensor.">Optical visualization of cathepsin K activity in atherosclerosis with a novel, protease-activatable fluorescence sensor.</a> Circulation. 115 (17), 2292-2298 (2007).</li><li>Jaffer, F. A., Libby, P., Weissleder, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+and+multimodality+molecular+imaging:+insights+into+atherosclerosis.">Optical and multimodality molecular imaging: insights into atherosclerosis.</a> Arteriosclerosis, Thrombosis, and Vascular Biology. 29 (7), 1017-1024 (2009).</li><li>Razansky, 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=Multispectral+optoacoustic+tomography+of+matrix+metalloproteinase+activity+in+vulnerable+human+carotid+plaques.">Multispectral optoacoustic tomography of matrix metalloproteinase activity in vulnerable human carotid plaques.</a> Molecular Imaging and Biology. 14 (3), 277-285 (2012).</li><li>Hsia, A. 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=Osteophytes+and+fracture+calluses+share+developmental+milestones+and+are+diminished+by+unloading.">Osteophytes and fracture calluses share developmental milestones and are diminished by unloading.</a> Journal of Orthopaedic Research. 36 (2), 699-710 (2018).</li><li>Blaker, C. L., Little, C. B., Clarke, E. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Joint+loads+resulting+in+ACL+rupture:+Effects+of+age,+sex,+and+body+mass+on+injury+load+and+mode+of+failure+in+a+mouse+model.">Joint loads resulting in ACL rupture: Effects of age, sex, and body mass on injury load and mode of failure in a mouse model.</a> Journal of Orthopaedic Research. 35 (8), 1754-1763 (2017).</li><li>Murata, 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=Controlling+joint+instability+delays+the+degeneration+of+articular+cartilage+in+a+rat+model.">Controlling joint instability delays the degeneration of articular cartilage in a rat model.</a> Osteoarthritis Cartilage. 25 (2), 297-308 (2017).</li><li>Murata, 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=Controlling+Abnormal+joint+movement+inhibits+response+of+osteophyte+formation.">Controlling Abnormal joint movement inhibits response of osteophyte formation.</a> Cartilage. 9 (4), 391-401 (2018).</li><li>Yardeni, T., Eckhaus, M., Morris, H. D., Huizing, M., Hoogstraten-Miller, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Retro-orbital+injections+in+mice.">Retro-orbital injections in mice.</a> Laboratory Animals (NY). 40 (5), 155-160 (2011).</li><li>Kokubun, 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=Effect+of+changing+the+joint+kinematics+of+knees+with+a+ruptured+anterior+cruciate+ligament+on+the+molecular+biological+responses+and+spontaneous+healing+in+a+rat+model.">Effect of changing the joint kinematics of knees with a ruptured anterior cruciate ligament on the molecular biological responses and spontaneous healing in a rat model.</a> The American Journal of Sports Medicine. 44 (11), 2900-2910 (2016).</li><li>Bhatti, F. U., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+non-invasively+induced+post-traumatic+osteoarthritis+in+mice.">Characterization of non-invasively induced post-traumatic osteoarthritis in mice.</a> Antioxidants (Basel). 11 (9), 1783 (2022).</li><li>Steel, C. D., Stephens, A. L., Hahto, S. M., Singletary, S. J., Ciavarra, R. P. <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+the+lateral+tail+vein+and+the+retro-orbital+venous+sinus+as+routes+of+intravenous+drug+delivery+in+a+transgenic+mouse+model.">Comparison of the lateral tail vein and the retro-orbital venous sinus as routes of intravenous drug delivery in a transgenic mouse model.</a> Laboratory Animals (NY). 37 (1), 26-32 (2008).</li></ol>

This protocol has established and rigorously described a reproducible, non-invasive method for inducing ACL injury in mice20,21,24,33. This simple and efficient injury method can be performed in just a few minutes, which facilitates high-throughput studies of PTOA. This injury method also closely recapitulates injury conditions relevant to human ACL injury. Surgical methods used to induce OA in...

Osteoarthritis is a pervasive health issue that affects millions of people in the United States1. Post-traumatic osteoarthritis (PTOA) is a subset of OA that is initiated by a joint injury such as anterior cruciate ligament (ACL) rupture, meniscus injury, or intra-articular fracture2. The proportion of symptomatic OA patients that can be classified as PTOA is at least 12%3, and this etiology typically affects a younger population than idiopathic OA4. Mouse models of OA are crucial tools for investigating disease etiology and potential OA treatments on a much shorter timeline (4-12 weeks in mouse models compared to 10-20 years in humans). However, the methods to initiate OA in mice commonly involve invasive surgical techniques such as ACL transection5,6, removal or destabilization of the medial meniscus5,7,8,9,10,11,12,13,14,15,16, or a combination of the two17,18,19, which do not reproduce clinically relevant injury conditions. Surgical models also exacerbate inflammation in the joint due to disruption of the joint capsule, which could accelerate OA progression.
Non-invasive knee injury mouse models provide the opportunity to study biological and biomechanical changes at early time points post-injury and may yield more clinically relevant results20. Our lab has established a non-invasive injury model that uses a single externally applied tibial compression overload to induce anterior cruciate ligament (ACL) rupture in mice21,22,23,24. This non-invasive injury method is able to produce an aseptic joint injury without disrupting the skin or joint capsule.
Fluorescence reflectance imaging (FRI) is an optical imaging method that involves exciting a target with infrared light at a specific wavelength and quantifying the reflected light emitted at another wavelength. Commercially available protease-specific probes can be injected into animal models and FRI can then be used to quantify protease activity at specific sites such as the knee joint. This method has been widely used for in vivo detection of biological activities such as inflammation. The probes used for this application are fluorescently quenched until they encounter relevant proteases. Those proteases will then break an enzyme cleavage site on the probes, after which they will produce a near-infrared fluorescent signal. These probes and this imaging method have been extensively validated and used in studies of cancer25,26,27,28 and atherosclerosis29,30,31,32, and our group has used them for studies of the musculoskeletal system to measure markers of inflammation and matrix degradation23,24,33.
Together, non-invasive joint injury combined with in vivo FRI and protease activatable probes provide a unique ability to track inflammation and protease activity following a traumatic joint injury. This analysis can be done as early as hours or even minutes after injury, and the same animal can be assessed multiple times to study the time course of protease activity in the joint. Importantly, this imaging method may not be feasible when combined with surgical models of OA, since disruption of the skin and joint capsule results in a fluorescence signal that would confound the signal from within the joint.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>10x Phosphate-Buffered Saline</td>
			<td>Tissue Protech</td>
			<td>PBS01-32R</td>
			<td>or equivalent</td>
		</tr>
		<tr>
			<td>Air Anesthetia System</td>
			<td></td>
			<td></td>
			<td>Isoflurane vaporizor with induction chamber and nose cone</td>
		</tr>
		<tr>
			<td>Buprenorphine</td>
			<td></td>
			<td></td>
			<td>Analgesic post-injury&#160;</td>
		</tr>
		<tr>
			<td>Depilatory Cream</td>
			<td>Veet</td>
			<td>B001KYPZ4G</td>
			<td>or equivalent</td>
		</tr>
		<tr>
			<td>Fixtures</td>
			<td></td>
			<td></td>
			<td>Custom-made knee fixture, ankle fixture, and platform</td>
		</tr>
		<tr>
			<td>IVIS Spectrum</td>
			<td>Perkin Elmer</td>
			<td>124262</td>
			<td>Can also use comparable optical imaging system</td>
		</tr>
		<tr>
			<td>Kimwipes</td>
			<td>Kimberly-Clark Corporation</td>
			<td>06-666</td>
			<td>or equivalent</td>
		</tr>
		<tr>
			<td>Living Image software&#160;</td>
			<td>Perkin Elmer</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Materials testing systems&#160;</td>
			<td>TA Instruments</td>
			<td></td>
			<td>Electroforce 3200 or equivalent</td>
		</tr>
		<tr>
			<td>ProSense680</td>
			<td>Perkin Elmer</td>
			<td>NEV10003</td>
			<td>Can also use other probes such as OsteoSense, MMPSense, Cat K, AngioSense, etc.</td>
		</tr>
		<tr>
			<td>Sterile Syringe with Needle</td>
			<td>Spectrum Chemical Mfg. Corp.</td>
			<td>550-82231-CS</td>
			<td>Covidien 1 mL TB Syringe with 28 G x 1/2 in. Needle, Sterile or equivalent</td>
		</tr>
		<tr>
			<td>Uniaxial load cell</td>
			<td>TA Instruments</td>
			<td></td>
			<td>20 N capacity</td>
		</tr>
		<tr>
			<td>Vortex-Genie 2</td>
			<td>Scientific Industries, Inc.</td>
			<td>SI-0236</td>
			<td>or equivalent</td>
		</tr>
		<tr>
			<td>WinTest software&#160;</td>
			<td>TA Instruments</td>
			<td></td>
			<td>compatible with Electroforce 3200</td>
		</tr>
	</tbody>
</table>

non-invasive compression-induced anterior cruciate ligament (acl) injury and in vivo imaging of protease activity in mice

Traumatic joint injuries such as anterior cruciate ligament (ACL) rupture or meniscus tears commonly lead to post-traumatic osteoarthritis (PTOA) within 10-20 years following injury. Understanding the early biological processes initiated by joint injuries (e.g., inflammation, matrix metalloproteinases (MMPs), cathepsin proteases, bone resorption) is crucial for understanding the etiology of PTOA. However, there are few options for in vivo measurement of these biological processes, and the early biological responses may be confounded if invasive surgical techniques or injections are used to initiate OA. In our studies of PTOA, we have used commercially available near-infrared protease activatable probes combined with fluorescence reflectance imaging (FRI) to quantify protease activity in vivo following non-invasive compression-induced ACL injury in mice. This non-invasive ACL injury method closely recapitulates clinically relevant injury conditions and is completely aseptic since it does not involve disrupting the skin or the joint capsule. The combination of these injury and imaging methods allows us to study the time course of protease activity at multiple time points following a traumatic joint injury.

Author Spotlight: Investigating Early Events and Long-Term Effects of ACL Injuries for Osteoarthritis Progression

Non-Invasive Compression-Induced Anterior Cruciate Ligament (ACL) Injury and In Vivo Imaging of Protease Activity in Mice

Our lab uses mouse models of post-traumatic osteoarthritis to investigate early processes following joint injuries such as anterior cruciate ligament or ACL ruptures, and how these early events can lead to tissue degeneration and osteoarthritis progression. In particular, we're interested in learning how exercise or rest after an injury can affect long-term joint health. There are many animal models of osteoarthritis available, and all of them are useful for investigating certain research questions.Some of the experimental challenges in this field are selecting the appropriate models of your study, determining what techniques to use to assess OA progression, and at what time point you will perform this analysis. This knee injury method is very quick and easy to perform. Using noninvasive compression-induced injury also allows us to study the joint response at early time points, and since there's no surgical procedure, we can use in vivo optical imaging to track proteus activity in their joint.In the future, we plan to use different genetic strains of mice, some that are vulnerable to osteoarthritis, and some that are resistant to osteoarthritis to determine how certain aspects of the inflammatory response contribute to either joint healing or joint degeneration following injury.

After applying a single compressive force (1 mm/s until injury) on the lower legs of 3-month-old male C57BL/6J mice, ACL injury was consistently induced in all mice. The average compressive force at knee injury was approximately 10 N (Figure 1).
FRI analysis showed significantly greater protease activity in the injured joints of mice subjected to non-invasive ACL injury at 7 days following injury (Figure 2). FRI analysis of knee joint...

Watch this Scientific Journal Video about Author Spotlight: Investigating Early Events and Long-Term Effects of ACL Injuries for Osteoarthritis Progression at JoVE.com

Non-invasive ACL injury is a reliable and clinically relevant method for initiating post-traumatic osteoarthritis (PTOA) in mice. This injury method also allows for in vivo quantification of protease activity in the joint at early time points post-injury using protease-activatable near infrared probes and fluorescence reflectance imaging.

Traumatic joint injuries such as anterior cruciate ligament (ACL) rupture or meniscus tears commonly lead to post-traumatic osteoarthritis (PTOA) within ...

non-invasive-compression-induced-anterior-cruciate-ligament-acl