This work was supported partly by NIH research grants R01AR062207, R01AR061484, R56AI100901, K01AR053210, and a Disease Targeted Research Grant from Rheumatology Research Foundation (to C. J. Liu).

All of the surgical procedures relating to the animals should be approved by local Institution&#39;s Animal Care and Ethics Committee, with an effort made to minimize pain and discomfort caused by the surgery.
1. Preparation
<ol>
	<li>Select 8-12 weeks old male C57BL/6 mice with a body weight of approximately 25 g for surgery.</li>
	<li>Anesthetize the animals through intraperitoneal injection of a cocktail containing both xylazine (5 mg/kg) and ketamine (40 mg/kg).</li>
	<li>Shave the knee with razors, then surgically drape the animal and sterilize the surgical site with betadine and alcohol (3x) and cover the mouse eyes with ointment.</li>
</ol>
2. Surgical Process
<ol>
	<li>Make a 1 cm longitudinal medial para-patellar incision to expose knee joint.</li>
	<li>Open the knee joint gently through lateral dislocation of the patella and patellar ligament.
	<ol>
		<li>Cut the knee joint capsule longitudinally through the medial para-patellar incision in step&#160;2.1.</li>
		<li>Dissect knee joint capsule with forceps.</li>
		<li>Grab the distal part of hind paw with left hand, and perform lateral dislocation of the patella and patellar ligament with forceps. Hold the hind paw gently and make sure to avoid trauma in the paw. The better the joint capsule is dissected, the less force will be required to make the dislocation.</li>
	</ol>
	</li>
	<li>Drip sterile saline on the surface of articular cartilage during operation to avoid drying out of cartilage surface.</li>
	<li>Cut through the medial meniscotibial ligament which anchors medial meniscus to the tibial plateau. Avoid injuring the cartilage beneath the medial meniscus.
	<ol>
		<li>Identify the medial meniscus which locates between medial condyle of femur and medial plateau of tibia.</li>
		<li>Identify the meniscotibial ligament which connects lateral side of medial meniscus with intercondylar eminence of tibia.</li>
		<li>Hold the hind paw gently with hand, and cut through the medial meniscotibial ligament carefully by using a No. 10 surgical blade. Make sure not to cause injure to articular cartilage and other ligaments. In many cases, the covering fat pad needs to be pulled to the side but not to be removed in order to identify the ligament.</li>
	</ol>
	</li>
	<li>Close the knee joint capsule with a 6-0 absorbable suture.</li>
	<li>Close the skin with 6-0 silk suture.</li>
</ol>
3. Post-operative Care
<ol>
	<li>Apply one drop of 0.25% bupivacaine in the surgical site of each mouse to minimize post-operative pain.</li>
	<li>Leave the operated mice free to get water and food.</li>
</ol>
4. Histological Scoring of Surgical DMM Model
<ol>
	<li>Sacrifice the mice at indicated time points (e.g. 4 weeks, 8 weeks, and 12 weeks. Here we showed results of 8 weeks as representative) after the surgery.</li>
	<li>The entire knee joints are fixed, decalcified, embedded by paraffin and then sectioned serially at 5 &#181;m interval.
	<ol>
		<li>Cut the whole hind limbs with No. 10 blades.</li>
		<li>Dissect the skin and muscles of the hind limbs carefully, and fix the samples with 4% PFA for 3 days in RT.</li>
		<li>Remove the PFA, and clean the samples with water. Afterwards, decalcify the samples in EDTA at 4 &#176;C for 2 weeks.</li>
		<li>Dehydrate the samples in an ethanol gradient. In detail, keep the samples in 70% ethanol for 1 hr, then change the ethanol and keep the samples in a new set of 70% ethanol for O/N. Afterwards, put the samples in 80% and 90% ethanol consequently, and keep them for 1 hr, respectively, followed by 100% ethanol for O/N.</li>
		<li>Remove the ethanol. Keep the samples in oxylene for 1 hr, and change to a new set of oxylene. Repeat this step 3x.</li>
		<li>Embed the samples into a paraffin mold using the Leica embedding center. Afterwards, the samples are sectioned at 5 &#956;m using a rotary microtome (Leica RM2255, Germany)&#160;and then collected&#160;onto glass slides.</li>
		<li>Serial sagittal sections are cut for each sample spanning a region from the center of the lateral condyle to the center of the medial condyle.</li>
	</ol>
	</li>
	<li>Safranin O staining is performed, followed by scoring and statistical analysis through OARSI scoring system as described previously25.
	<ol>
		<li>First, deparaffinize the slides in oxylene, and hydrate them in an ethanol gradient to distilled water. Thereafter, the slides are stained through Weigert&#39;s Iron Hematoxylin Solution, 0.05% Fast Green (FCF) Solution, 1% Acetic Acid Solution, and 0.1% Safranin O Solution. Mount the slides using resinous medium.</li>
		<li>Score the Safranin O stained slides based on loss of proteoglycan (red color) in cartilage and percentage of destruction in cartilage structure, do statistical analysis for the histological score.</li>
	</ol>
	</li>
</ol>

<ol>
	<li>Herndon, J. H., Davidson, S. M., Apazidis, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+socioeconomic+trends+in+orthopaedic+practice.">Recent socioeconomic trends in orthopaedic practice.</a> J. Bone Joint Surg. Am. 83, 1097-1105 (2001).</li><li>Johnson, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+stem+cell-based+approach+to+cartilage+repair.">A stem cell-based approach to cartilage repair.</a> Science. 336, 717-721 (2012).</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> Nat. Med. 16, 687-693 (2010).</li><li>Glasson, S. 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=Deletion+of+active+ADAMTS5+prevents+cartilage+degradation+in+a+murine+model+of+osteoarthritis.">Deletion of active ADAMTS5 prevents cartilage degradation in a murine model of osteoarthritis.</a> Nature. 434, 644-648 (2005).</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> Osteoarthr. Cart. 15, 1061-1069 (2007).</li><li>Chia, 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=Fibroblast+growth+factor+2+is+an+intrinsic+chondroprotective+agent+that+suppresses+ADAMTS-5+and+delays+cartilage+degradation+in+murine+osteoarthritis.">Fibroblast growth factor 2 is an intrinsic chondroprotective agent that suppresses ADAMTS-5 and delays cartilage degradation in murine osteoarthritis.</a> Arthritis Rheum. 60, 2019-2027 (2009).</li><li>Miller, R. 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=CCR2+chemokine+receptor+signaling+mediates+pain+in+experimental+osteoarthritis.">CCR2 chemokine receptor signaling mediates pain in experimental osteoarthritis.</a> Proc. Natl. Acad. Sci. U.S.A. 109, 20602-20607 (2012).</li><li>Wang, Q., 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=Identification+of+a+central+role+for+complement+in+osteoarthritis.">Identification of a central role for complement in osteoarthritis.</a> Nat. Med. 17, 1674-1679 (2011).</li><li>He, Z., Ong, C. H., Halper, J., Bateman, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Progranulin+is+a+mediator+of+the+wound+response.">Progranulin is a mediator of the wound response.</a> Nat. Med. 9, 225-229 (2003).</li><li>Bateman, A., Bennett, H. 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Invest. 118, 2438-2447 (2008).</li><li>Yin, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exaggerated+inflammation,+impaired+host+defense,+and+neuropathology+in+progranulin-deficient+mice.">Exaggerated inflammation, impaired host defense, and neuropathology in progranulin-deficient mice.</a> J. Exp. Med. 207, 117-128 (2010).</li><li>Liu, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Progranulin:+A+promising+therapeutic+target+for+rheumatoid+arthritis.">Progranulin: A promising therapeutic target for rheumatoid arthritis.</a> FEBS Lett. , (2011).</li><li>Tang, 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=The+growth+factor+progranulin+binds+to+TNF+receptors+and+is+therapeutic+against+inflammatory+arthritis+in+mice.">The growth factor progranulin binds to TNF receptors and is therapeutic against inflammatory arthritis in mice.</a> Science. 332, 478-484 (2011).</li><li>Zhu, 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=Conversion+of+proepithelin+to+epithelins:+roles+of+SLPI+and+elastase+in+host+defense+and+wound+repair.">Conversion of proepithelin to epithelins: roles of SLPI and elastase in host defense and wound repair.</a> Cell. 111, 867-878 (2002).</li><li>Baker, 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=Mutations+in+progranulin+cause+tau-negative+frontotemporal+dementia+linked+to+chromosome+17.">Mutations in progranulin cause tau-negative frontotemporal dementia linked to chromosome 17.</a> Nature. 442, 916-919 (2006).</li><li>Cruts, 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=Null+mutations+in+progranulin+cause+ubiquitin-positive+frontotemporal+dementia+linked+to+chromosome+17q21.">Null mutations in progranulin cause ubiquitin-positive frontotemporal dementia linked to chromosome 17q21.</a> Nature. 442, 920-924 (2006).</li><li>Wils, 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=Cellular+ageing,+increased+mortality+and+FTLD-TDP-associated+neuropathology+in+progranulin+knockout+mice.">Cellular ageing, increased mortality and FTLD-TDP-associated neuropathology in progranulin knockout mice.</a> J. Pathol. , (2012).</li><li>Guo, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Granulin-epithelin+precursor+binds+directly+to+ADAMTS-7+and+ADAMTS-12+and+inhibits+their+degradation+of+cartilage+oligomeric+matrix+protein.">Granulin-epithelin precursor binds directly to ADAMTS-7 and ADAMTS-12 and inhibits their degradation of cartilage oligomeric matrix protein.</a> Arthritis Rheum. 62, 2023-2036 (2010).</li><li>Xu, 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=Cartilage+oligomeric+matrix+protein+associates+with+granulin-epithelin+precursor+(GEP)+and+potentiates+GEP-stimulated+chondrocyte+proliferation.">Cartilage oligomeric matrix protein associates with granulin-epithelin precursor (GEP) and potentiates GEP-stimulated chondrocyte proliferation.</a> J. Biol. Chem. 282, 11347-11355 (2007).</li><li>Bai, X. 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=ADAMTS-7,+a+direct+target+of+PTHrP,+adversely+regulates+endochondral+bone+growth+by+associating+with+and+inactivating+GEP+growth+factor.">ADAMTS-7, a direct target of PTHrP, adversely regulates endochondral bone growth by associating with and inactivating GEP growth factor.</a> Mol. Cell. Biol. 29, 4201-4219 (2009).</li><li>Feng, J. Q., 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=Granulinepithelin+precursor:+a+bone+morphogenic+protein+2-inducible+growth+factor+that+activates+Erk1/2+signaling+and+JunB+transcription+factor+in+chondrogenesis.">Granulinepithelin precursor: a bone morphogenic protein 2-inducible growth factor that activates Erk1/2 signaling and JunB transcription factor in chondrogenesis.</a> FASEB J. 24, 1879-1892 (2010).</li><li>Liu, C. J., Bosch, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Progranulin:+A+growth+factor,+a+novel+TNFR+ligand+and+a+drug+target.">Progranulin: A growth factor, a novel TNFR ligand and a drug target.</a> Pharmacol. Therap. 133, 124-132 (2012).</li><li>Wu, H., Siegel, 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=Progranulin+Resolves+Inflammation.">Progranulin Resolves Inflammation.</a> Science. 332, 427-428 (2011).</li><li>Glasson, S. S., Chambers, M. G., Den Berg, W. B. V. a. n., Little, C. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+OARSI+histopathology+initiative+-+recommendations+for+histological+assessments+of+osteoarthritis+in+the+mouse.">The OARSI histopathology initiative - recommendations for histological assessments of osteoarthritis in the mouse.</a> Osteoarthr. Cart. 18, 17-23 (2010).</li><li>Glasson, S. S. <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+osteoarthritis+target+validation+utilizing+genetically-modified+mice.">In vivo osteoarthritis target validation utilizing genetically-modified mice.</a> Curr. Drug Targets. 8, 367-376 (2007).</li><li>Ma, H. L. <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> Osteoarthr. Cart. 15, 695-700 (2007).</li><li>Lin, A. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modulating+hedgehog+signaling+can+attenuate+the+severity+of+osteoarthritis.">Modulating hedgehog signaling can attenuate the severity of osteoarthritis.</a> Nat. Med. 15, 1421-1425 (2009).</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> Osteoarthr. Cart. 18, 572-580 (2010).</li></ol>

We herein declare that we have no conflict of interest.

It is reported that the strain of mice is very important for DMM model induction, as different strains of mice have varying severity of OA after DMM, with highest level in the 129/SvEv strain, followed by C57BL6, 129/SvInJ and then FVB/n26. A large part of transgenes are established in C57BL6 mice, such as PGRN-/- mice we used in the present study, which are relatively susceptible to DMM. However, if the transgene is based on insensitive strain such as FVB/n mice, it is necessary to backcross these mice with s...

Osteoarthritis (OA), also known as degenerative arthritis, affects 15% of the world&#39;s population and over 46 million people within the United States, and is characterized by synovitis, cartilage degeneration, and osteophyte formation1. It can be a result of a complex interplay of genetic, metabolic, biomechanical and biochemical factors. The underlying mechanisms of OA continue to evade the scientific community. There are presently numerous animal models which can mimic the pathogenesis of OA2,3. It is important to establish animal models in mice because of both the availability of various genetically modified mice and the cost effectiveness of experimentation. Among the different kinds of experimental OA models, the surgically induced destabilization of medial meniscus (DMM) model is a well-accepted OA model because of its good reproducibility and a relatively slower progression during OA development.&#160;Both of these attributes have been key for the evaluation of OA progression in different treatments or transgenes3-8. However, the consistency of surgical OA model is affected by various factors during the surgery and as a result, the application of surgical mouse model is limited.
Progranulin (PGRN) is a multi-functional growth factor expressed in various cells. It is known that PGRN plays a critical role in various physiological and disease processes such as wound healing 9, tumorigenesis10, and inflammation11-15. Studies also shown that insufficiency of PGRN can cause degenerative diseases of nervous system in both humans and mice16-18. It is known that PGRN is expressed in human articular cartilage, and its level is significantly elevated in cartilage of patients with OA and rheumatoid arthritis19. In addition, PGRN also plays a crucial role in chondrocyte proliferation 20, differentiation and endochondral ossification of growth plate during development 21,22. Recently, we reported that PGRN antagonized TNF-&#945; through binding to TNF receptors and exhibited an anti-inflammatory function in inflammatory arthritis models13,14,23,24. However, the role of PGRN in OA, especially in vivo, remains to be an enigma. Herein, we present the procedure to induce a surgical DMM model, and investigate the role of PGRN in OA development through establishing DMM model in WT and PGRN-/- mice.

<table border="0" cellpadding="0" cellspacing="0" width="637">
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			<td height="21" style="height:21px;width:216px;">No. 10 Surgical blades</td>
			<td style="width:135px;">FEATHER</td>
			<td style="width:119px;">25-2976#10</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">6-0 suture</td>
			<td>APPLIED DENTAL</td>
			<td>WG-N53133</td>
			<td></td>
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establishment of a surgically-induced model in mice to investigate the protective role of progranulin in osteoarthritis

Destabilization of medial meniscus (DMM) model is an important tool for studying the pathophysiological roles of numerous arthritis associated molecules in the pathogenesis of osteoarthritis (OA) in vivo. However, the detailed, especially the visualized protocol for establishing this complicated model in mice, is not available. Herein we took advantage of wildtype and progranulin (PGRN)-/- mice as examples to introduce a protocol for inducing DMM model in mice, and compared the onset of OA following establishment of this surgically induced model. The operations performed on mice were either sham operation, which just opened joint capsule, or DMM operation, which cut the menisco-tibial ligament and caused destabilization of medial meniscus. Osteoarthritis severity was evaluated using histological assay (e.g. Safranin&#160;O staining), expressions of OA-associated genes, degradation of cartilage extracellular matrix molecules, and osteophyte formation. DMM operation successfully induced OA initiation and progression in both wildtype and PGRN-/- mice, and loss of PGNR growth factor led to a more severe OA phenotype in this surgically induced model.

DMM model was successfully established in mice, and deficiency of PGRN exaggerated surgically-induced OA development.
Sham and DMM operations (Figure 1) were performed in WT and PGRN-/- mice. 8 weeks after operation, the mice were sacrificed, and Safranin O staining was performed on the sections from knee joints, followed by statistical analysis of arthritis score based on histology. As shown in Figure 2A, there was no obvious degeneration of ...

Watch this Scientific Journal Video about Establishment of a Surgically-induced Model in Mice to Investigate the Protective Role of Progranulin in Osteoarthritis at JoVE.com

Establishment of a Surgically-induced Model in Mice to Investigate the Protective Role of Progranulin in Osteoarthritis

We describe a protocol for the destabilization of the medial meniscus (DMM) model in mice, an effective tool for osteoarthritis (OA) research. In addition, we have demonstrated that deficiency of progranulincan exaggerate OA development and progression by using this model, indicating that progranulin plays a protective role in the pathogenesis of OA.

Destabilization of medial meniscus (DMM) model is an important tool for studying the pathophysiological roles of numerous arthritis associated molecules ...

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Bioengineering

27.2K Views.  NYU Hospital for Joint Diseases.  Descriviamo un protocollo per la destabilizzazione del menisco mediale (DMM) modello nei topi, uno strumento efficace per l'osteoartrite (OA) la ricerca. Inoltre, abbiamo dimostrato che la carenza di progranulincan esagerata sviluppo OA e progressione utilizzando questo modello, indicando che progranulin svolge un ruolo protettivo nella patogenesi di OA. 

Video: Establishment of a Surgically-induced Model in Mice to Investigate the Protective Role of Progranulin in Osteoarthritis

Multiparametric Optical Mapping of the Langendorff-perfused Rabbit Heart

Optical imaging and fluorescent probes have significantly advanced research methodology in the field of cardiac electrophysiology in ways that could not have been accomplished by other approaches1. With the use of the calcium- and voltage-sensitive dyes, optical mapping allows measurement of transmembrane action potentials and calcium transients with high spatial resolution without the physical contact with the tissue. This makes measurements of the cardiac electrical activity possible under many conditions where the use of electrodes is inconvenient or impossible1. For example, optical recordings provide accurate morphological changes of membrane potential during and immediately after stimulation and defibrillation, while conventional electrode techniques suffer from stimulus-induced artifacts during and after stimuli due to electrode polarization1. 
The Langendorff-perfused rabbit heart is one of the most studied models of human heart physiology and pathophysiology. Many types of arrhythmias observed clinically could be recapitulated in the rabbit heart model. It was shown that wave patterns in the rabbit heart during ventricular arrhythmias, determined by effective size of the heart and the wavelength of reentry, are very similar to that in the human heart2. It was also shown that critical aspects of excitation-contraction (EC) coupling in rabbit myocardium, such as the relative contribution of sarcoplasmic reticulum (SR), is very similar to human EC coupling3. Here we present the basic procedures of optical mapping experiments in Langendorff-perfused rabbit hearts, including the Langendorff perfusion system setup, the optical mapping systems setup, the isolation and cannulation of the heart, perfusion and dye-staining of the heart, excitation-contraction uncoupling, and collection of optical signals. These methods could be also applied to the heart from species other than rabbit with adjustments to flow rates, optics, solutions, etc.
Two optical mapping systems are described. The panoramic mapping system is used to map the entire epicardium of the rabbit heart4-7. This system provides a global view of the evolution of reentrant circuits during arrhythmogenesis and defibrillation, and has been used to study the mechanisms of arrhythmias and antiarrhythmia therapy8,9. The dual mapping system is used to map the action potential (AP) and calcium transient (CaT) simultaneously from the same field of view10-13. This approach has enhanced our understanding of the important role of calcium in the electrical alternans and the induction of arrhythmia14-16.

This article describes the basic procedures for conducting optical mapping experiments in the Langendorff-perfused rabbit heart using the panoramic imaging system, and the dual (voltage and calcium) imaging modality.

Optical imaging and fluorescent probes have significantly advanced research methodology in the field of cardiac electrophysiology in ways that could not ...

Creating Two-Dimensional Patterned Substrates for Protein and Cell Confinement

Microcontact printing provides a rapid, highly reproducible method for the creation of well-defined patterned substrates.1 While microcontact printing can be employed to directly print a large number of molecules, including proteins,2 DNA,3 and silanes,4 the formation of self-assembled monolayers (SAMs) from long chain alkane thiols on gold provides a simple way to confine proteins and cells to specific patterns containing adhesive and resistant regions. This confinement can be used to control cell morphology and is useful for examining a variety of questions in protein and cell biology. Here, we describe a general method for the creation of well-defined protein patterns for cellular studies.5 This process involves three steps: the production of a patterned master using photolithography, the creation of a PDMS stamp, and microcontact printing of a gold-coated substrate. Once patterned, these cell culture substrates are capable of confining proteins and/or cells (primary cells or cell lines) to the pattern.
The use of self-assembled monolayer chemistry allows for precise control over the patterned protein/cell adhesive regions and non-adhesive regions; this cannot be achieved using direct protein stamping. Hexadecanethiol, the long chain alkane thiol used in the microcontact printing step, produces a hydrophobic surface that readily adsorbs protein from solution. The glycol-terminated thiol, used for backfilling the non-printed regions of the substrate, creates a monolayer that is resistant to protein adsorption and therefore cell growth.6 These thiol monomers produce highly structured monolayers that precisely define regions of the substrate that can support protein adsorption and cell growth. As a result, these substrates are useful for a wide variety of applications from the study of intercellular behavior7 to the creation of microelectronics.8
While other types of monolayer chemistry have been used for cell culture studies, including work from our group using trichlorosilanes to create patterns directly on glass substrates,9 patterned monolayers formed from alkane thiols on gold are straight-forward to prepare. Moreover, the monomers used for monolayer preparation are commercially available, stable, and do not require storage or handling under inert atmosphere. Patterned substrates prepared from alkane thiols can also be recycled and reused several times, maintaining cell confinement.10

Self-assembled monolayers (SAMs) formed from long chain alkane thiols on gold provide well-defined substrates for the formation of protein patterns and cell confinement. Microcontact printing of hexadecanethiol using a polydimethylsiloxane (PDMS) stamp followed by backfilling with a glycol-terminated alkane thiol monomer produces a pattern where protein and cells adsorb only to the stamped hexadecanethiol region.

Microcontact printing provides a rapid, highly reproducible method for the creation of well-defined patterned substrates.1  While microcontact printing ...

Design of a Cyclic Pressure Bioreactor for the Ex Vivo Study of Aortic Heart Valves

The aortic valve, located between the left ventricle and the aorta, allows for unidirectional blood flow, preventing backflow into the ventricle. Aortic valve leaflets are composed of interstitial cells suspended within an extracellular matrix (ECM) and are lined with an endothelial cell monolayer. The valve withstands a harsh, dynamic environment and is constantly exposed to shear, flexion, tension, and compression. Research has shown calcific lesions in diseased valves occur in areas of high mechanical stress as a result of endothelial disruption or interstitial matrix damage1-3. Hence, it is not surprising that epidemiological studies have shown high blood pressure to be a leading risk factor in the onset of aortic valve disease4. 
The only treatment option currently available for valve disease is surgical replacement of the diseased valve with a bioprosthetic or mechanical valve5. Improved understanding of valve biology in response to physical stresses would help elucidate the mechanisms of valve pathogenesis. In turn, this could help in the development of non-invasive therapies such as pharmaceutical intervention or prevention. Several bioreactors have been previously developed to study the mechanobiology of native or engineered heart valves6-9. Pulsatile bioreactors have also been developed to study a range of tissues including cartilage10, bone11 and bladder12. The aim of this work was to develop a cyclic pressure system that could be used to elucidate the biological response of aortic valve leaflets to increased pressure loads. 
The system consisted of an acrylic chamber in which to place samples and produce cyclic pressure, viton diaphragm solenoid valves to control the timing of the pressure cycle, and a computer to control electrical devices. The pressure was monitored using a pressure transducer, and the signal was conditioned using a load cell conditioner. A LabVIEW program regulated the pressure using an analog device to pump compressed air into the system at the appropriate rate. The system mimicked the dynamic transvalvular pressure levels associated with the aortic valve; a saw tooth wave produced a gradual increase in pressure, typical of the transvalvular pressure gradient that is present across the valve during diastole, followed by a sharp pressure drop depicting valve opening in systole. The LabVIEW program allowed users to control the magnitude and frequency of cyclic pressure. The system was able to subject tissue samples to physiological and pathological pressure conditions. This device can be used to increase our understanding of how heart valves respond to changes in the local mechanical environment.

Design of a Cyclic Pressure Bioreactor for the Ex Vivo Study of Aortic Heart Valves

A cyclic pressure bioreactor capable of subjecting heart valve tissue to physiological and pathological pressure conditions has been designed. A LabVIEW program allows users to control pressure magnitude, amplitude and frequency. This device can be used to study the mechanobiology of heart valve tissue or isolated cells.

The aortic valve, located between the left ventricle and the aorta, allows for unidirectional blood flow, preventing backflow into the ventricle. Aortic ...

Quantification of Global Diastolic Function by Kinematic Modeling-based Analysis of Transmitral Flow via the Parametrized Diastolic Filling Formalism

Quantitative cardiac function assessment remains a challenge for physiologists and clinicians.&#160;Although historically invasive methods have comprised the only means available, the development of noninvasive imaging modalities (echocardiography, MRI, CT) having high temporal and spatial resolution provide a new window for quantitative diastolic function assessment. Echocardiography is the agreed upon standard for diastolic function assessment, but indexes in current clinical use merely utilize selected features of chamber dimension (M-mode) or blood/tissue motion (Doppler) waveforms without incorporating the physiologic causal determinants of the motion itself.&#160;The recognition that all left ventricles (LV) initiate filling by serving as mechanical suction pumps allows global diastolic function to be assessed based on laws of motion that apply to all chambers. What differentiates one heart from another are the parameters of the equation of motion that governs filling. Accordingly, development of the Parametrized Diastolic Filling (PDF) formalism&#160;has shown that the entire range of clinically observed early transmitral flow (Doppler E-wave) patterns are extremely well fit by the laws of damped oscillatory motion.&#160;This permits analysis of individual E-waves in accordance with a causal mechanism (recoil-initiated suction) that yields three (numerically) unique lumped parameters whose physiologic analogues are chamber stiffness (k), viscoelasticity/relaxation (c), and load (xo).&#160;The recording of transmitral flow (Doppler E-waves) is standard practice in clinical cardiology and, therefore, the echocardiographic recording method is only briefly reviewed. Our focus is on determination of the PDF parameters from routinely recorded E-wave data.&#160;As the highlighted results indicate, once the PDF parameters have been obtained from a suitable number of load varying E-waves, the investigator is free to use the parameters or construct indexes from the parameters (such as stored energy 1/2kxo2, maximum A-V pressure gradient kxo, load independent index of diastolic function, etc.) and select the aspect of physiology or pathophysiology to be quantified.

Accurate, causality-based quantification of global diastolic function has been achieved by kinematic modeling-based analysis of transmitral flow via the Parametrized Diastolic Filling (PDF) formalism. PDF generates unique stiffness, relaxation,&#160;and load parameters and elucidates &#39;new&#39; physiology while providing sensitive and specific indexes of dysfunction.

Quantitative cardiac function assessment remains a challenge for physiologists and clinicians.&#160;Although historically invasive methods have comprised ...

Production, Characterization and Potential Uses of a 3D Tissue-engineered Human Esophageal Mucosal Model

The incidence of both esophageal adenocarcinoma and its precursor, Barrett&#8217;s Metaplasia, are rising rapidly in the western world. Furthermore esophageal adenocarcinoma generally has a poor prognosis, with little improvement in survival rates in recent years. These are difficult conditions to study and there has been a lack of suitable experimental platforms to investigate disorders of the esophageal mucosa.
A model of the human esophageal mucosa has been developed in the MacNeil laboratory which, unlike conventional 2D cell culture systems, recapitulates the cell-cell and cell-matrix interactions present in vivo and produces a mature, stratified epithelium similar to that of the normal human esophagus. Briefly, the model utilizes non-transformed normal primary human esophageal fibroblasts and epithelial cells grown within a porcine-derived acellular esophageal scaffold. Immunohistochemical characterization of this model by CK4, CK14, Ki67 and involucrin staining demonstrates appropriate recapitulation of the histology of the normal human esophageal mucosa.
This model provides a robust, biologically relevant experimental model of the human esophageal mucosa. It can easily be manipulated to investigate a number of research questions including the effectiveness of pharmacological agents and the impact of exposure to environmental factors such as alcohol, toxins, high temperature or gastro-esophageal refluxate components. The model also facilitates extended culture periods not achievable with conventional 2D cell culture, enabling, inter alia, the study of the impact of repeated exposure of a mature epithelium to the agent of interest for up to 20 days. Furthermore, a variety of cell lines, such as those derived from esophageal tumors or Barrett&#8217;s Metaplasia, can be incorporated into the model to investigate processes such as tumor invasion and drug responsiveness in a more biologically relevant environment.

This manuscript describes the production, characterization and potential uses of a tissue engineered 3D esophageal construct prepared from normal primary human esophageal fibroblast and squamous epithelial cells seeded within a de-cellularized porcine scaffold. The results demonstrate the formation of a mature stratified epithelium similar to the normal human esophagus.

The incidence of both esophageal adenocarcinoma and its precursor, Barrett&#8217;s Metaplasia, are rising rapidly in the western world. Furthermore ...

Planar Gradient Diffusion System to Investigate Chemotaxis in a 3D Collagen Matrix

The importance of cell migration can be seen through the development of human life. When cells migrate, they generate forces and transfer these forces to their surrounding area, leading to cell movement and migration. In order to understand the mechanisms that can alter and/or affect cell migration, one can study these forces. In theory, understanding the fundamental mechanisms and forces underlying cell migration holds the promise of effective approaches for treating diseases and promoting cellular transplantation. Unfortunately, modern chemotaxis chambers that have been developed are usually restricted to two dimensions (2D) and have complex diffusion gradients that make the experiment difficult to interpret. To this end, we have developed, and describe in this paper, a direct-viewing chamber for chemotaxis studies, which allows one to overcome modern chemotaxis chamber obstacles able to measure cell forces and specific concentration within the chamber in a 3D environment to study cell 3D migration. More compelling, this approach allows one to successfully model diffusion through 3D collagen matrices and calculate the coefficient of diffusion of a chemoattractant through multiple different concentrations of collagen, while keeping the system simple and user friendly for traction force microscopy (TFM) and digital volume correlation (DVC) analysis.

Cell migration is an important part of human development and life. In order to understand the mechanisms that can alter cell migration, we present a planar gradient diffusion system to investigate chemotaxis in a 3D collagen matrix, which allows one to overcome modern diffusion chamber limitations of existing assays.

The importance of cell migration can be seen through the development of human life. When cells migrate, they generate forces and transfer these forces to ...

An In Vitro Organ Culture Model of the Murine Intervertebral Disc

Intervertebral disc (IVD) degeneration is a significant contributor to low back pain. The IVD is a fibrocartilaginous joint that serves to transmit and dampen loads in the spine. The IVD consists of a proteoglycan-rich nucleus pulposus (NP) and a collagen-rich annulus fibrosis (AF) sandwiched by cartilaginous end-plates. Together with the adjacent vertebrae, the vertebrae-IVD structure forms a functional spine unit (FSU). These microstructures contain unique cell types as well as unique extracellular matrices. Whole organ culture of the FSU preserves the native extracellular matrix, cell differentiation phenotypes, and cellular-matrix interactions. Thus, organ culture techniques are particularly useful for investigating the complex biological mechanisms of the IVD. Here, we describe a high-throughput approach for culturing whole lumbar mouse FSUs that provides an ideal platform for studying disease mechanisms and therapies for the IVD. Furthermore, we describe several applications that utilize this organ culture method to conduct further studies including contrast-enhanced microCT imaging and three-dimensional high-resolution finite element modeling of the IVD.

An In Vitro Organ Culture Model of the Murine Intervertebral Disc

Whole organ culture of the intervertebral disc (IVD) preserves the native extracellular matrix, cell phenotypes, and cellular-matrix interactions. Here we describe an IVD culture system using mouse lumbar and caudal IVDs in their functional spinal units and several applications utilizing this system.

Intervertebral disc (IVD) degeneration is a significant contributor to low back pain. The IVD is a fibrocartilaginous joint that serves to transmit and ...

Creating a Structurally Realistic Finite Element Geometric Model of a Cardiomyocyte to Study the Role of Cellular Architecture in Cardiomyocyte Systems Biology

With the advent of three-dimensional (3D) imaging technologies such as electron tomography, serial-block-face scanning electron microscopy and confocal microscopy, the scientific community has unprecedented access to large datasets at sub-micrometer resolution that characterize the architectural remodeling that accompanies changes in cardiomyocyte function in health and disease. However, these datasets have been under-utilized for&#160;investigating the role of cellular architecture remodeling in cardiomyocyte function. The purpose of this protocol is to outline how to create an accurate finite element model of a cardiomyocyte using high resolution electron microscopy and confocal microscopy images. A detailed and accurate model of cellular architecture has significant potential to provide new insights into cardiomyocyte biology, more than experiments alone can garner. The power of this method lies in its ability to computationally fuse information from two disparate imaging modalities of cardiomyocyte ultrastructure to develop one unified and detailed model of the cardiomyocyte. This protocol outlines steps to integrate electron tomography and confocal microscopy images of adult male Wistar (name for a specific breed of albino rat) rat cardiomyocytes to develop a half-sarcomere finite element model of the cardiomyocyte. The procedure generates a 3D finite element model that contains an accurate, high-resolution depiction (on the order of ~35 nm) of the distribution of mitochondria, myofibrils and ryanodine receptor clusters that release the necessary calcium for cardiomyocyte contraction from the sarcoplasmic reticular network (SR) into the myofibril and cytosolic compartment. The model generated here as an illustration does not incorporate details of the transverse-tubule architecture or the sarcoplasmic reticular network and is therefore a minimal model of the cardiomyocyte. Nevertheless, the model can already be applied in simulation-based investigations into the role of cell structure in calcium signaling and mitochondrial bioenergetics, which is illustrated and discussed using two case studies that are presented following the detailed protocol.

This protocol outlines a novel method to create a spatially detailed finite element model of the intracellular architecture of cardiomyocytes from electron microscopy and confocal microscopy images. The power of this spatially detailed model is demonstrated using case studies in calcium signaling and bioenergetics.

With the advent of three-dimensional (3D) imaging technologies such as electron tomography, serial-block-face scanning electron microscopy and confocal ...

Calorespirometry: A Powerful, Noninvasive Approach to Investigate Cellular Energy Metabolism

Many cell lines used in basic biological and biomedical research maintain energy homeostasis through a combination of both aerobic and anaerobic respiration. However, the extent to which both pathways contribute to the landscape of cellular energy production is consistently overlooked. Transformed cells cultured in saturating levels of glucose often show a decreased dependency on oxidative phosphorylation for ATP production, which is compensated by an increase in substrate-level phosphorylation. This shift in metabolic poise allows cells to proliferate despite the presence of mitochondrial toxins. In neglecting the altered metabolic poise of transformed cells, results from a pharmaceutical screening may be misinterpreted since the potentially mitotoxic effects may not be detected using model cell lines cultured in the presence of high glucose concentrations. This protocol describes the pairing of two powerful techniques, respirometry and calorimetry, which allows for the quantitative and noninvasive assessment of both aerobic and anaerobic contributions to cellular ATP production. Both aerobic and anaerobic respirations generate heat, which can be monitored via calorimetry. Meanwhile, measuring the rate of oxygen consumption can assess the extent of aerobic respiration. When both heat dissipation and oxygen consumption are measured simultaneously, the calorespirometric ratio can be determined. The experimentally obtained value can then be compared to the theoretical oxycaloric equivalent and the extent of the anaerobic respiration can be judged. Thus, calorespirometry provides a unique method to analyze a wide range of biological questions, including drug development, microbial growth, and fundamental bioenergetics under both normoxic and hypoxic conditions.

This protocol describes calorespirometry, the direct and simultaneous measurement of both heat dissipation and respiration, which provides a noninvasive approach to assess energy metabolism. This technique is used to assess the contribution of both aerobic and anaerobic pathways to energy utilization by monitoring the total cellular energy flow.

Many cell lines used in basic biological and biomedical research maintain energy homeostasis through a combination of both aerobic and anaerobic ...

A Tripeptide-Stabilized Nanoemulsion of Oleic Acid

We describe a method to produce a nanoemulsion composed of an oleic acids-Pt(II) core and a lysine-tyrosine-phenylalanine (KYF) coating (KYF-Pt-NE). The KYF-Pt-NE encapsulates Pt(II) at 10 wt. %, has a diameter of 107 &#177; 27 nm and a negative surface charge. The KYF-Pt-NE is stable in water and in serum, and is biologically active. The conjugation of a fluorophore to KYF allows the synthesis of a fluorescent nanoemulsion that is suitable for biological imaging. The synthesis of the nanoemulsion is performed in an aqueous environment, and the KYF-Pt-NE forms via self-assembly of a short KYF peptide and an oleic acids-platinum(II) conjugate. The self-assembly process depends on the temperature of the solution, the molar ratio of the substrates, and the flow rate of the substrate addition. Crucial steps include maintaining the optimal stirring rate during the synthesis, permitting sufficient time for self-assembly, and pre-concentrating the nanoemulsion gradually in a centrifugal concentrator.

This protocol describes an efficient method to synthesize a nanoemulsion of an oleic acids-platinum(II) conjugate stabilized with a lysine-tyrosine-phenylalanine (KYF) tripeptide. The nanoemulsion forms under mild synthetic conditions via self-assembly of the KYF and the conjugate.

We describe a method to produce a nanoemulsion composed of an oleic acids-Pt(II) core and a lysine-tyrosine-phenylalanine (KYF) coating (KYF-Pt-NE). The ...