This project was funded by the German Research Association (DFG, HE 4578/3-1).

A. Cartilage Biopsy (Surgery Room; Steps 1-5 in Non-sterile Preparation Room)
<ol>
	<li>Perform a final weight control of the rabbit (New Zealand White rabbit, female, 3.5-4.0 kg body weight, 6 months old) in order to be able to dose drugs properly and to monitor weight subsequent to surgery.</li>
	<li>Induce anesthesia to the rabbit by an intravenous injection of 10 mg/kg propofol.</li>
	<li>After intubation, maintain anesthesia with 1.5 mg/kg/min propofol and 0.05 mg/kg fentanyl intravenously. Monitor anesthesia by using capnography, pulse oximetry and pulse rate.</li>
	<li>Shave the knee to be operated on with an electric clipper and vacuum the fur.</li>
	<li>Disinfect the shaved knee thoroughly and cover the rest of the rabbit with a sterile dressing.</li>
	<li>Palpate the patella and perform a skin incision medially of the patella.</li>
	<li>Open the knee joint by a medial parapatellar arthrotomy under sterile conditions. Try to avoid cutting any small superficial blood vessels.</li>
	<li>Displace the patella laterally.</li>
	<li>Inspect the knee joint for any anomalies and macroscopic cartilage lesions.</li>
	<li>Carefully peel small cartilage pieces (2-3 mm) out of the trochlea ossis femoris with a sterile scalpel (Figure 1).</li>
	<li>Immediately place these cartilage biopsies into a 50 ml tube with complete medium (DMEM + 10% fetal calf serum (FCS) + 1% penicillin/streptomycin (Pen/Strep)) to continue with the in vitro culture right after the operation.</li>
	<li>Clean the defects and rinse them with sterile saline.</li>
	<li>Reposition the patella within the trochlea groove.</li>
	<li>Wound closure in layers with single button sutures (4-0 Vicryl) and a continuing cutaneous suture (4-0 Monocryl). Use absorbable suture material.</li>
	<li>Finally, seal the wound with a spray dressing permeable to water vapor.</li>
</ol>
B. In vitro Culture
<ol>
	<li>Process the biopsied cartilage pieces as soon as possible after the operation in a sterile laminar flow tissue culture hood.</li>
	<li>Wash the sterile harvested cartilage 2x in PBS with subsequent centrifugation at 500 x g for 3 min at RT.</li>
	<li>Cut cartilage in pieces of 1 mm3, transfer to a 50 ml falcon and digest them on a shaker for 30 min with 10 ml trypsin-EDTA (0.25%) and 10 ml PBS for 30 min</li>
	<li>After 30 min, stop trypsinization by adding complete medium. Then, shake the cartilage pieces for another for 12 hr with Collagenase A (0.21 U/mg) in serum free medium (DMEM + 1% Pen/Strep).</li>
	<li>Centrifuge the resulting solution at 170 x g for 3 min at RT.</li>
	<li>Resuspend cell pellets in 5 ml complete medium.</li>
	<li>Seed the isolated chondrocytes on to 25 cm2 tissue culture flasks in 5 ml complete medium and keep in a humidified tissue culture incubator at 37 &deg;C, 5% CO2.</li>
	<li>Grow chondrocytes to a density of 80%.</li>
	<li>Release the cells from flasks by washing in PBS 2x before exposing to 0.05% trypsin-EDTA for 3 min. Once chondrocytes detach, stop trypsinization by addition of 10 &mu;l complete medium.</li>
	<li>Centrifuge the suspension at 300 x g (3 min) and resuspend pellet in complete medium.</li>
	<li>Seed cells in tissue culture flasks (75 cm2) and split at a ratio of 1:3 (&sim;5,000 cells/cm2) every 5th day or upon 80% confluency.</li>
	<li>Determine cell numbers and viability by trypan blue staining.</li>
</ol>
C. Cell-seeding of the Matrix
<ol>
	<li>Prior to implantation wash and release cells as described above. Perform cell count and transfer 5 x 104 cells into a 1.5 ml microcentrifuge tube. Then centrifuge at 500 x g for 5 min at RT.</li>
	<li>Resuspend pellet in 15 &mu;l complete medium for a complete saturation of the matrix.</li>
	<li>Cut the bilayer collagen scaffold to the exact dimensions of the trochlear defect by a sterile biopsy punch.</li>
	<li>Place matrix into an appropriately sized tissue culture dish (e.g. 24-well plates).</li>
	<li>Seed cells onto the porous, cell-adhesive side of the matrix. This deters cell migration away from the matrix.</li>
	<li>Leave cell-seeded matrices without further cell culture medium within an incubator for 1 hr to allow full adherence of the chondrocytes.</li>
	<li>Then, place cell-matrix-constructs into culturing containers (e.g. 24-well plates) with fresh complete medium. Take care not to wash out any cells off the matrix even though strong adherence is expected.</li>
	<li>Now, cell-matrix-constructs can be taken to the surgery room for re-implantation.</li>
</ol>
D. Matrix-assisted Autologous Chondrocyte Transplantation
<ol>
	<li>Perform parapatellar arthrotomy to the contralateral knee as described above (A. 1-8).</li>
	<li>Create two isolated chondral defects in the trochlear groove with a sterile air operating power drill (3.6 mm in diameter).</li>
	<li>Clean the defect and rinse with sterile saline.</li>
	<li>Attention should be paid not to open the marrow cavity at any time. If necessary, seal the bottom of the defects with electrical cautery against bleeding.</li>
	<li>Implant the matrices seeded with the cultured chondrocytes with the porous side face down (Figure 2). Then press-fit into the drill holes and flush the surrounding surface.</li>
	<li>Seal the implanted matrices with a little bit of fibrin glue (Tissucol Duo S) to assure secure fixation.</li>
	<li>After clotting, relocate the patella within the trochlear groove and apply full range of motion to the knee joint a few times.</li>
	<li>Displace the patella laterally once again and check for any event or sign of instable fixation. The matrices must be held still in place.</li>
	<li>Replace the patella again and finish the operation with wound closure in layers and spray dressing as described above.</li>
</ol>

<ol>
	<li>Albrecht, 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=Gene+expression+and+cell+differentiation+in+matrix-associated+chondrocyte+transplantation+grafts:+a+comparative+study.">Gene expression and cell differentiation in matrix-associated chondrocyte transplantation grafts: a comparative study.</a> Osteoarthritis Cartilage. 19, 1219-1227 (2011).</li><li>Pridie, K. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+method+of+resurfacing+osteoarthritic+knee+joints.">A method of resurfacing osteoarthritic knee joints.</a> J. Bone Joint Surg. Br. 41, 618-619 (1959).</li><li>Johnson, L. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Arthroscopic+abrasion+arthroplasty+historical+and+pathologic+perspective:+present+status.">Arthroscopic abrasion arthroplasty historical and pathologic perspective: present status.</a> Arthroscopy. 2, 54-69 (1986).</li><li>Steadman, J. R., Rodkey, W. G., Singelton, S. B., Briggs, K. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microfracture+technique+for+full-thickness+chondral+defects:+technique+and+clinical+result.">Microfracture technique for full-thickness chondral defects: technique and clinical result.</a> Operat. Tech. Orthop. 7, 300-304 (1997).</li><li>Brittberg, 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=Treatment+of+deep+cartilage+defects+in+the+knee+with+autologous+chondrocyte+transplantation.">Treatment of deep cartilage defects in the knee with autologous chondrocyte transplantation.</a> N. Engl. J. Med. 331, 889-895 (1994).</li><li>Peterson, L., Vasiliadis, H. S., Brittberg, M., Lindahl, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Autologous+chondrocyte+implantation:+a+long-term+follow-up.">Autologous chondrocyte implantation: a long-term follow-up.</a> Am. J. Sports Med. 38, 1117-1124 (2010).</li><li>Nehrer, 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=Chondrocyte-seeded+collagen+matrices+implanted+in+a+chondral+defect+in+a+canine+model.">Chondrocyte-seeded collagen matrices implanted in a chondral defect in a canine model.</a> Biomaterials. 19, 2313-2328 (1998).</li><li>Frenkel, S. R., Toolan, B., Menche, D., Pitman, M. I., Pachence, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chondrocyte+transplantation+using+a+collagen+bilayer+matrix+for+cartilage+repair.">Chondrocyte transplantation using a collagen bilayer matrix for cartilage repair.</a> J. Bone. Joint Surg. Br. 79, 831-836 (1997).</li><li>Salzmann, G. 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=The+dependence+of+autologous+chondrocyte+transplantation+on+varying+cellular+passage,+yield+and+culture+duration.">The dependence of autologous chondrocyte transplantation on varying cellular passage, yield and culture duration.</a> Biomaterials. 32, 5810-5818 (2011).</li><li>Frohlich, M., Malicev, E., Gorensek, M., Knezevic, M., Kregar Velikonja, N. <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+rabbit+auricular+chondrocyte+isolation+and+growth+parameters+in+cell+culture.">Evaluation of rabbit auricular chondrocyte isolation and growth parameters in cell culture.</a> Cell Biol. Int. 31, 620-625 (2007).</li><li>Willers, C., Chen, J., Wood, D., Xu, J., Zheng, M. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Autologous+chondrocyte+implantation+with+collagen+bioscaffold+for+the+treatment+of+osteochondral+defects+in+rabbits.">Autologous chondrocyte implantation with collagen bioscaffold for the treatment of osteochondral defects in rabbits.</a> Tissue Eng. 11, 1065-1076 (2005).</li><li>Vogt, 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=The+influence+of+the+stable+expression+of+BMP2+in+fibrin+clots+on+the+remodelling+and+repair+of+osteochondral+defects.">The influence of the stable expression of BMP2 in fibrin clots on the remodelling and repair of osteochondral defects.</a> Biomaterials. 30, 2385-2392 (2009).</li><li>Ueblacker, P., 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+analysis+of+retroviral+gene+transfer+to+chondrocytes+within+collagen+scaffolds+for+the+treatment+of+osteochondral+defects.">In vivo analysis of retroviral gene transfer to chondrocytes within collagen scaffolds for the treatment of osteochondral defects.</a> Biomaterials. 28, 4480-4487 (2007).</li><li>Marlovits, S., Zeller, P., Singer, P., Resinger, C., Vecsei, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cartilage+repair:+generations+of+autologous+chondrocyte+transplantation.">Cartilage repair: generations of autologous chondrocyte transplantation.</a> Eur. J. Radiol. 57, 24-31 (2006).</li><li>Benya, P. D., Shaffer, 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=Dedifferentiated+chondrocytes+reexpress+the+differentiated+collagen+phenotype+when+cultured+in+agarose+gels.">Dedifferentiated chondrocytes reexpress the differentiated collagen phenotype when cultured in agarose gels.</a> Cell. 30, 215-224 (1982).</li><li>Rudert, M., Hirschmann, F., Wirth, 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=Growth+behavior+of+chondrocytes+on+various+biomaterials.">Growth behavior of chondrocytes on various biomaterials.</a> Orthopade. 28, 68-75 (1999).</li><li>Hsu, S. 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=Evaluation+of+biodegradable+polyesters+modified+by+type+II+collagen+and+Arg-Gly-Asp+as+Tissue+Engineering+scaffolding+materials+for+cartilage+regeneration.">Evaluation of biodegradable polyesters modified by type II collagen and Arg-Gly-Asp as Tissue Engineering scaffolding materials for cartilage regeneration.</a> Artificial Organs. 30, 42-55 (2006).</li><li>Brun, P., Cortivo, R., Zavan, B., Vecchiato, N., Abatangelo, G. <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++reconstructed+tissues+on+hyaluronan-based+temporary+scaffolding.">In vitro reconstructed tissues on hyaluronan-based temporary scaffolding.</a> J. Mater. Sci. Mater. Med. 10, 683-688 (1999).</li><li>Domm, C., Fay, J., Schunke, M., Kurz, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Redifferentiation+of+dedifferentiated+joint+cartilage+cells+in+alginate+culture.+Effect+of+intermittent+hydrostatic+pressure+and+low+oxygen+partial+pressure.">Redifferentiation of dedifferentiated joint cartilage cells in alginate culture. Effect of intermittent hydrostatic pressure and low oxygen partial pressure.</a> Orthopade. 29, 91-99 (2000).</li><li>Kimura, T., Yasui, N., Ohsawa, S., Ono, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chondrocytes+embedded+in+collagen+gels+maintain+cartilage+phenotype+during+long-term+cultures.">Chondrocytes embedded in collagen gels maintain cartilage phenotype during long-term cultures.</a> Clin. Orthop. Relat. Res. , 231-239 (1984).</li><li>Kon, 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=Second-generation+autologous+chondrocyte+implantation:+results+in+patients+older+than+40+years.">Second-generation autologous chondrocyte implantation: results in patients older than 40 years.</a> Am. J. Sports Med. 39, 1668-1675 (2011).</li><li>Gavenis, K., Schmidt-Rohlfing, B., Mueller-Rath, R., Andereya, S., Schneider, U. <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+comparison+of+six+different+matrix+systems+for+the+cultivation+of+human+chondrocytes.">In vitro comparison of six different matrix systems for the cultivation of human chondrocytes.</a> In Vitro Cell Dev. Biol. Anim. 42, 159-167 (2006).</li><li>Niemeyer, P., 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=Characteristic+complications+after+autologous+chondrocyte+implantation+for+cartilage+defects+of+the+knee+joint.">Characteristic complications after autologous chondrocyte implantation for cartilage defects of the knee joint.</a> Am. J. Sports Med. 36, 2091-2099 (2008).</li><li>Tay, L. X., 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=Treatment+outcomes+of+alginate-embedded+allogenic+mesenchymal+stem+cells+versus+autologous+chondrocytes+for+the+repair+of+focal+articular+cartilage+defects+in+a+rabbit+model.">Treatment outcomes of alginate-embedded allogenic mesenchymal stem cells versus autologous chondrocytes for the repair of focal articular cartilage defects in a rabbit model.</a> The American Journal of Sports Medicine. 40, 83-90 (2012).</li><li>Brittberg, M., Nilsson, A., Lindahl, A., Ohlsson, C., Peterson, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rabbit+articular+cartilage+defects+treated+with+autologous+cultured+chondrocytes.">Rabbit articular cartilage defects treated with autologous cultured chondrocytes.</a> Clin. Orthop. Relat. Res. , 270-283 (1996).</li></ol>

The authors have nothing to disclose.

The presented protocol provides an established 9,12,13 and easily reproducible technique to isolate autologous chondrocytes for subsequent proliferation and re-implantation into artificially created cartilage defects in rabbit knees. The use of autologous chondrocytes for remodeling and repair of articular cartilage lesions is already in clinical use providing satisfying long-term results 6.
Major problems as for example periosteal hypertrophy and calcification, graft del...

<table border="1">
	<tbody>
		<tr>
			<td>Name of reagent/equipment</td>
			<td>Company</td>
			<td>Catalogue Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>Biochrom AG</td>
			<td>F 0415</td>
			<td></td>
		</tr>
		<tr>
			<td>Collagenase A</td>
			<td>Roche</td>
			<td>10 103 586 001</td>
			<td>0.21 U/mg</td>
		</tr>
		<tr>
			<td>Fetal calf serum (FCS)</td>
			<td>PAN Biotech GmbH</td>
			<td>3702-P103009</td>
			<td></td>
		</tr>
		<tr>
			<td>Propofol</td>
			<td>Fresenius Kabi</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin/Streptomycin</td>
			<td>Biochrom AG</td>
			<td>A 2213</td>
			<td>10,000 U/ml/10,000 &mu;g/ml</td>
		</tr>
		<tr>
			<td>PBS Dulbecco (1X)</td>
			<td>Biochrom AG</td>
			<td>L1815</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol (70%)</td>
			<td>Merck KgaA</td>
			<td>410230</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin-EDTA 0.25 %/0.02 %</td>
			<td>Biochrom AG</td>
			<td>L2163</td>
			<td>in PBS w/o Ca2+, Mg2+</td>
		</tr>
		<tr>
			<td>Fentanyl</td>
			<td>Delta Select GmBH</td>
			<td>1819340</td>
			<td></td>
		</tr>
		<tr>
			<td>NaCl solution (0.9%)</td>
			<td>Bbraun</td>
			<td>8333A193</td>
			<td></td>
		</tr>
		<tr>
			<td>Tissue culture dishes 100 mm/150 mm</td>
			<td>TPP AG</td>
			<td>93100/93150</td>
			<td>Growth area 60.1 mm2/147.8 mm2</td>
		</tr>
		<tr>
			<td>Tissue culture flasks 25/75 mm2</td>
			<td>TPP AG</td>
			<td>90025/90075</td>
			<td>25 mm2, 75 mm2</td>
		</tr>
		<tr>
			<td>Centrifuge Tubes (50 ml)</td>
			<td>TPP AG</td>
			<td>91050</td>
			<td>Gamma-sterilized</td>
		</tr>
		<tr>
			<td>Hemocytometer</td>
			<td>Brand GmbH+Co KG</td>
			<td>717810</td>
			<td>Neubauer</td>
		</tr>
		<tr>
			<td>Trypan Blue Solution 0.4%</td>
			<td>Sigma-Aldrich</td>
			<td>L8154</td>
			<td></td>
		</tr>
		<tr>
			<td>Spray dressing (OpSite)</td>
			<td>Smith&amp;Nephew</td>
			<td>66004978</td>
			<td>Permeable for water vapor</td>
		</tr>
		<tr>
			<td>Chondro-Gide&Ograve;</td>
			<td>Geistlich Pharma AG</td>
			<td>30915.5</td>
			<td></td>
		</tr>
		<tr>
			<td>Biopsy Punch</td>
			<td>pfm medical ag</td>
			<td>48351</td>
			<td></td>
		</tr>
		<tr>
			<td>Tissucol Duo S</td>
			<td>Baxter</td>
			<td>3419627</td>
			<td>0.5 ml</td>
		</tr>
	</tbody>
</table>

matrix-assisted autologous chondrocyte transplantation for remodeling and repair of chondral defects in a rabbit model

Articular cartilage defects are considered a major health problem because articular cartilage has a limited capacity for self-regeneration 1. Untreated cartilage lesions lead to ongoing pain, negatively affect the quality of life and predispose for osteoarthritis. During the last decades, several surgical techniques have been developed to treat such lesions. However, until now it was not possible to achieve a full repair in terms of covering the defect with hyaline articular cartilage or of providing satisfactory long-term recovery 2-4. Therefore, articular cartilage injuries remain a prime target for regenerative techniques such as Tissue Engineering. In contrast to other surgical techniques, which often lead to the formation of fibrous or fibrocartilaginous tissue, Tissue Engineering aims at fully restoring the complex structure and properties of the original articular cartilage by using the chondrogenic potential of transplanted cells. Recent developments opened up promising possibilities for regenerative cartilage therapies.
The first cell based approach for the treatment of full-thickness cartilage or osteochondral lesions was performed in 1994 by Lars Peterson and Mats Brittberg who pioneered clinical autologous chondrocyte implantation (ACI) 5. Today, the technique is clinically well-established for the treatment of large hyaline cartilage defects of the knee, maintaining good clinical results even 10 to 20 years after implantation 6. In recent years, the implantation of autologous chondrocytes underwent a rapid progression. The use of an artificial three-dimensional collagen-matrix on which cells are subsequently replanted became more and more popular 7-9.
MACT comprises of two surgical procedures: First, in order to collect chondrocytes, a cartilage biopsy needs to be performed from a non weight-bearing cartilage area of the knee joint. Then, chondrocytes are being extracted, purified and expanded to a sufficient cell number in vitro. Chondrocytes are then seeded onto a three-dimensional matrix and can subsequently be re-implanted. When preparing a tissue-engineered implant, proliferation rate and differentiation capacity are crucial for a successful tissue regeneration 10. The use of a three-dimensional matrix as a cell carrier is thought to support these cellular characteristics 11.
The following protocol will summarize and demonstrate a technique for the isolation of chondrocytes from cartilage biopsies, their proliferation in vitro and their seeding onto a 3D-matrix (Chondro-Gide, Geistlich Biomaterials, Wollhusen, Switzerland). Finally, the implantation of the cell-matrix-constructs into artificially created chondral defects of a rabbit's knee joint will be described. This technique can be used as an experimental setting for further experiments of cartilage repair.

The described surgical technique permits a successful isolation and implantation of autologous chondrocytes into an artificial chondral defect. The experimental setup resulted in a successful integration of the implant into the surrounding cartilage.
After 12 weeks in vivo, the chondral defect was filled by repair tissue with a homogenous and intact surface, which reduced shear stress and damage to the implant (Figure 4). Moreover, no hypertrophy or calcification of t...

Watch this Scientific Journal Video about Matrix-assisted Autologous Chondrocyte Transplantation for Remodeling and Repair of Chondral Defects in a Rabbit Model at JoVE.com

Matrix-assisted Autologous Chondrocyte Transplantation for Remodeling and Repair of Chondral Defects in a Rabbit Model

An experimental technique for the treatment of chondral defects in the rabbit's knee joint is described. The implantation of autologous chondrocytes seeded on a matrix is a well-accepted method for the remodeling and repair of articular cartilage lesions providing satisfying long-term results. Matrix-assisted autologous chondrocyte transplantation (MACT) offers a standardized and clinically established implantation method.

Articular cartilage defects are considered a major health problem because articular cartilage has a limited capacity for self-regeneration 1. Untreated ...

matrix-assisted-autologous-chondrocyte-transplantation-for-remodeling

Research

JoVE Journal

Medicine

14.3K Views.  Klinikum rechts der Isar der Technischen Universität München. Una tecnica sperimentale per il trattamento dei difetti condrali in ginocchio di coniglio è descritto. L'impianto di condrociti autologhi seminate su una matrice è un metodo ben accettato per il rimodellamento e la riparazione di lesioni della cartilagine articolare che fornisca risultati soddisfacenti a lungo termine. Matrix-assistito trapianto autologo di condrociti (MACT) offre un metodo standardizzato di impianto e clinicamente stabilita.

Video: Matrix-assisted Autologous Chondrocyte Transplantation for Remodeling and Repair of Chondral Defects in a Rabbit Model

A Mouse Model of in Utero Transplantation

The transplantation of stem cells and viruses in utero has tremendous potential for treating congenital disorders in the human fetus. For example, in utero transplantation (IUT) of hematopoietic stem cells has been used to successfully treat patients with severe combined immunodeficiency.1,2 In several other conditions, however, IUT has been attempted without success.3 Given these mixed results, the availability of an efficient non-human model to study the biological sequelae of stem cell transplantation and gene therapy is critical to advance this field. We and others have used the mouse model of IUT to study factors affecting successful engraftment of in utero transplanted hematopoietic stem cells in both wild-type mice4-7 and those with genetic diseases.8,9 The fetal environment also offers considerable advantages for the success of in utero gene therapy. For example, the delivery of adenoviral10, adeno-associated viral10, retroviral11, and lentiviral vectors12,13 into the fetus has resulted in the transduction of multiple organs distant from the site of injection with long-term gene expression. in utero gene therapy may therefore be considered as a possible treatment strategy for single gene disorders such as muscular dystrophy or cystic fibrosis. Another potential advantage of IUT is the ability to induce immune tolerance to a specific antigen. As seen in mice with hemophilia, the introduction of Factor IX early in development results in tolerance to this protein.14 
In addition to its use in investigating potential human therapies, the mouse model of IUT can be a powerful tool to study basic questions in developmental and stem cell biology. For example, one can deliver various small molecules to induce or inhibit specific gene expression at defined gestational stages and manipulate developmental pathways. The impact of these alterations can be assessed at various timepoints after the initial transplantation. Furthermore, one can transplant pluripotent or lineage specific progenitor cells into the fetal environment to study stem cell differentiation in a non-irradiated and unperturbed host environment.
The mouse model of IUT has already provided numerous insights within the fields of immunology, and developmental and stem cell biology. In this video-based protocol, we describe a step-by-step approach to performing IUT in mouse fetuses and outline the critical steps and potential pitfalls of this technique.

A Mouse Model of in Utero Transplantation

The mouse model of in utero transplantation is a versatile tool that can be used to study the potential clinical applications of stem cell transplantation and gene therapy in the fetus. In this protocol, we present a general approach to performing this technique

The transplantation of stem cells and viruses in utero has tremendous potential for treating congenital disorders in the human fetus.  For example, in ...

Development of Obliterative Bronchiolitis in a Murine Model of Orthotopic Lung Transplantation

Orthotopic lung transplantation in rats was first reported by Asimacopoulos and colleagues in 1971 1. Currently, this method is well accepted and standardized not only for the study of allo-rejection but also between syngeneic strains for examining mechanisms of ischemia-reperfusion injury after lung transplantation. Although the application of the rat and other large animal model 2 contributed significantly to the elucidation of these studies, the scope of those investigations is limited by the scarcity of knockout and transgenic rats. Due to no effective therapies for obliterative bronchiolitis, the leading cause of death in lung transplant patients, there has been an intensive search for pre-clinical models that replicate obliterative bronchiolitis. The tracheal allograft model is the most widely used and may reproduce some of the histopathologic features of obliterative bronchiolitis 3. However, the lack of an intact vasculature with no connection to the recipient's conducting airways, and incomplete pathologic features of obliterative bronchiolitis limit the utility of this model 4. Unlike transplantation of other solid organs, vascularized mouse lung transplants have only recently been reported by Okazaki and colleagues for the first time in 2007 5. Applying the basic principles of the rat lung transplant, our lab initiated the obliterative bronchiolitis model using minor histoincompatible antigen murine orthotopic single-left lung transplants which allows the further study of obliterative bronchiolitis immunopathogenesis6.

Obliterative bronchiolitis is the key impediment to the long-term survival of lung transplant recipients and the lack of a robust preclinical model precludes examining obliterative bronchiolitis immunopathogenesis. Unlike other solid organ transplants, vascularized mouse lung transplantation has only recently been developed. Here we show our independently developed obliterative bronchiolitis model after murine orthotopic single-lung transplantation.

Orthotopic lung transplantation in rats was first reported by Asimacopoulos and colleagues in 1971 1. Currently, this method is well accepted and ...

A Mouse Fetal Skin Model of Scarless Wound Repair

Early in utero, but not in postnatal life, cutaneous wounds undergo regeneration and heal without formation of a scar. Scarless fetal wound healing occurs across species but is age dependent. The transition from a scarless to scarring phenotype occurs in the third trimester of pregnancy in humans and around embryonic day 18 (E18) in mice. However, this varies with the size of the wound with larger defects generating a scar at an earlier gestational age. The emergence of lineage tracing and other genetic tools in the mouse has opened promising new avenues for investigation of fetal scarless wound healing. However, given the inherently high rates of morbidity and premature uterine contraction associated with fetal surgery, investigations of fetal scarless wound healing in vivo require a precise and reproducible surgical model. Here we detail a reliable model of fetal scarless wound healing in the dorsum of E16.5 (scarless) and E18.5 (scarring) mouse embryos.

During mammalian development, early gestational skin wounds heal without a scar. Here we detail a reliable and reproducible model of fetal scarless wound healing in the cutaneous dorsum of E16.5 (scarless) and E18.5 (scarring) mouse embryos.

Early in utero, but not in postnatal life, cutaneous wounds undergo regeneration and heal without formation of a scar. Scarless fetal wound healing occurs ...

Scleral Cross-linking Using Riboflavin and Ultraviolet-A Radiation for Prevention of Axial Myopia in a Rabbit Model

Myopic individuals, especially those with severe myopia, are at higher-than-normal risk of cataract, glaucoma, retinal detachment and chorioretinal abnormalities. In addition, pathological myopia is a common irreversible cause of visual impairment and blindness1-3. Our study demonstrates the effect of scleral crosslinking using riboflavin and ultraviolet-A radiation on the development of axial myopia in a rabbit model. The axial length of the eyeball was measured by A-scan ultrasound in New Zealand white rabbits aged 13 days (male and female). The eye then underwent 360&#176; conjunctival peritomy with scleral crosslinking, followed by tarsorrhaphy. Axial elongation was induced in 13 day-old New Zealand rabbits by suturing their right eye eyelids (tarsorrhaphy). The eyes were divided into quadrants, and every quadrant had two scleral irradiation zones, each with an area of 0.2 cm&#178; and a radius of 4 mm. Crosslinking was performed by dropping 0.1% dextran-free riboflavin-5-phosphate onto the irradiation zones 20 sec before ultraviolet-A irradiation and every 20 sec during the 200 sec irradiation time. UVA radiation (370 nm) was applied perpendicular to the sclera at 57 mW/cm&#178; (total UVA light dose, 57 J/cm&#178;). Tarsorrhaphies were removed on day 55, followed by repeated axial length measurements. This study demonstrates that scleral crosslinking with riboflavin and ultraviolet-A radiation effectively prevents occlusion-induced axial elongation in a rabbit model.

We demonstrate the effect of scleral crosslinking with riboflavin and UVA on an axial elongation rabbit eye. Axial elongation was induced in 13 day-old New Zealand rabbits (male and female) by suturing their right eye eyelids (tarsorrhaphy).

Myopic individuals, especially those with severe myopia, are at higher-than-normal risk of cataract, glaucoma, retinal detachment and chorioretinal ...

A Rat Carotid Balloon Injury Model to Test Anti-vascular Remodeling Therapeutics

The rat carotid balloon injury is a well-established surgical model that has been used to study arterial remodeling and vascular cell proliferation. It is also a valuable model system to test, and to evaluate therapeutics and drugs that negate maladaptive remodeling in the vessel. The injury, or barotrauma, in the vessel lumen caused by an inflated balloon via an inserted catheter induces subsequent neointimal growth, often leading to hyperplasia or thickening of the vessel wall that narrows, or obstructs the lumen. The method described here is sufficiently sensitive, and the results can be obtained in relatively short time (2 weeks after the surgery). The efficacy of the drug or therapeutic against the induced-remodeling can be evaluated either by the post-mortem pathological and histomorphological analysis, or by ultrasound sonography in live animals. In addition, this model system has also been used to determine the therapeutic window or the time course of the administered drug. These studies can leadto the development of a better administrative strategy and a better therapeutic outcome. The procedure described here provides a tool for translational studies that bring drug and therapeutic candidates from bench research to clinical applications.

The rat carotid balloon injury model described below allows researchers to evaluate drugs or therapeutics that negate injury-induced arterial hyperplasia. Detailed pre-surgical preparation, surgical procedure, and post-surgical cares of the animal are described.

The rat carotid balloon injury is a well-established surgical model that has been used to study arterial remodeling and vascular cell proliferation. It is ...

Lentiviral Vector-mediated Gene Therapy of Hepatocytes Ex Vivo for Autologous Transplantation in Swine

Gene therapy is an ideal choice to cure many inborn errors of metabolism of the liver. Ex-vivo, lentiviral vectors have been used successfully in the treatment of many hematopoietic diseases in humans, as their use offers stable transgene expression due to the vector&#39;s ability to integrate into the host genome. This method demonstrates the application of ex vivo gene therapy of hepatocytes to a large animal model of hereditary tyrosinemia type I. This process consists of 1) isolation of primary hepatocytes from the autologous donor/recipient animal, 2) ex vivo gene delivery via hepatocyte transduction with a lentiviral vector, and 3) autologous transplant of corrected hepatocytes via portal vein injection. Success of the method generally relies upon efficient and sterile removal of the liver resection, careful handling of the excised specimen for isolation of viable hepatocytes sufficient for re-engrafting, high-percentage transduction of the isolated cells, and aseptic surgical procedures throughout to prevent infection. Technical failure at any of these steps will result in low yield of viable transduced hepatocytes for autologous transplant or infection of the donor/recipient animal. The pig model of human type 1 hereditary tyrosinemia (HT-1) chosen for this approach is uniquely amenable to such a method, as even a small percentage of engraftment of corrected cells will lead to repopulation of the liver with healthy cells based on a powerful selective advantage over native-diseased hepatocytes. Although this growth selection will not be true for all indications, this approach is a foundation for expansion into other indications and allows for manipulation of this environment to address additional diseases, both within the liver and beyond, while controlling for exposure to viral vector and opportunity for off-target toxicity and tumorigenicity.

Lentiviral Vector-mediated Gene Therapy of Hepatocytes Ex Vivo for Autologous Transplantation in Swine

This protocol is intended to describe porcine hepatocyte isolation and ex vivo gene delivery to cure models of metabolic diseases via autologous cell transplantation. Although this particular model enjoys unique advantages that favor successful therapy, the application is a relevant foundation to address additional diseases and indications.

Gene therapy is an ideal choice to cure many inborn errors of metabolism of the liver. Ex-vivo, lentiviral vectors have been used successfully in the ...

Transthoracic Echocardiographic Examination in the Rabbit Model

Large animal models such as the rabbit are valuable for translational preclinical research. Rabbits have a similar cardiac electrophysiology compared to that of humans and that of other large animal models such as dogs and pigs. However, the rabbit model has the additional advantage of lower maintenance costs compared to other large animal models. The longitudinal evaluation of cardiac function using echocardiography, when appropriately implemented, is a useful methodology for preclinical assessment of novel therapies for heart failure with reduced ejection fraction (e.g. cardiac regeneration). The correct use of this non-invasive tool requires the implementation of a standardized examination protocol following international guidelines. Here we describe, step by step, a detailed protocol supervised by veterinary cardiologists for performing echocardiography in the rabbit model, and demonstrate how to correctly obtain the different echocardiographic views and imaging planes, as well as the different imaging modes available in a clinical echocardiography system routinely used in human and veterinary patients.

Here we describe, step by step, a detailed protocol for performing echocardiography in the rabbit model. We show how to correctly obtain the different echocardiographic views and imaging planes, as well as the different imaging modes available in a clinical echocardiography system routinely used in human and veterinary patients.

Large animal models such as the rabbit are valuable for translational preclinical research. Rabbits have a similar cardiac electrophysiology compared to ...

Retinal Pigment Epithelium Transplantation in a Non-human Primate Model for Degenerative Retinal Diseases

Retinal pigment epithelial (RPE) transplantation holds great promise for the treatment of inherited and acquired retinal degenerative diseases. These conditions include retinitis pigmentosa (RP) and advanced forms of age-related macular degeneration (AMD), such as geographic atrophy (GA). Together, these disorders represent a significant proportion of currently untreatable blindness globally. These unmet medical needs have generated heightened academic interest in developing methods of RPE replacement. Among the animal models commonly utilized for preclinical testing of therapeutics, the non-human primate (NHP) is the only animal model that has a macula. As it shares this anatomical similarity with the human eye, the NHP eye is an important and appropriate preclinical animal model for the development of advanced therapy medicinal products (ATMPs) such as RPE cell therapy.
This manuscript describes a method for the submacular transplantation of an RPE monolayer, cultured on a polyethylene terephthalate (PET) cell carrier, underneath the macula onto a surgically created RPE wound in immunosuppressed NHPs. The fovea-the central avascular portion of the macula-is the site of the greatest mechanical weakness during the transplantation. Foveal trauma will occur if the initial subretinal fluid injection generates an excessive force on the retina. Hence, slow injection under perfluorocarbon liquid (PFCL) vitreous tamponade is recommended with a dual-bore subretinal injection cannula at low intraocular pressure (IOP) settings to create a retinal bleb. 
Pretreatment with an intravitreal plasminogen injection to release parafoveal RPE-photoreceptor adhesions is also advised. These combined strategies can reduce the likelihood of foveal tears when compared to conventional techniques. The NHP is a key animal model in the preclinical phase of RPE cell therapy development. This protocol addresses the technical challenges associated with the delivery of RPE cellular therapy in the NHP eye.

The non-human primate (NHP) is an ideal model for studying human retinal cellular therapeutics due to the anatomical and genetic similarities. This manuscript describes a method for submacular transplantation of retinal pigment epithelial cells in the NHP eye and strategies to prevent intraoperative complications associated with macular manipulation.

Retinal pigment epithelial (RPE) transplantation holds great promise for the treatment of inherited and acquired retinal degenerative diseases. These ...

A Simplified Model for Heterotopic Heart Valve Transplantation in Rodents

There is an urgent clinical need for heart valve replacements that can grow in children. Heart valve transplantation is proposed as a new type of transplant with the potential to deliver durable heart valves capable of somatic growth with no requirement for anticoagulation. However, the immunobiology of heart valve transplants remains unexplored, highlighting the need for animal models to study this new type of transplant. Previous rat models for heterotopic aortic valve transplantation into the abdominal aorta have been described, though they are technically challenging and costly. For addressing this challenge, a renal subcapsular transplant model was developed in rodents as a practical and more straightforward method for studying heart valve transplant immunobiology. In this model, a single aortic valve leaflet is harvested and inserted into the renal subcapsular space. The kidney is easily accessible, and the transplanted tissue is securely contained in a subcapsular space that is well vascularized and can accommodate a variety of tissue sizes. Furthermore, because a single rat can provide three donor aortic leaflets and a single kidney can provide multiple sites for transplanted tissue, fewer rats are required for a given study. Here, the transplantation technique is described, providing a significant step forward in studying the transplant immunology of heart valve transplantation.

This protocol describes a simple and efficient method for the transplantation of aortic valve leaflets under the renal capsule to allow for the study of alloreactivity of heart valves.

There is an urgent clinical need for heart valve replacements that can grow in children. Heart valve transplantation is proposed as a new type of ...

Left Lung Orthotopic Transplantation in a Juvenile Porcine Model for ESLP

Lung transplantation is the gold-standard treatment for end-stage lung disease, with over 4,600 lung transplantations performed worldwide annually. However, lung transplantation is limited by a shortage of available donor organs. As such, there is high waitlist mortality. Ex situ lung perfusion (ESLP) has increased donor lung utilization rates in some centers by 15%-20%. ESLP has been applied as a method to assess and recondition marginal donor lungs and has demonstrated acceptable short- and long-term outcomes following transplantation of extended criteria donor (ECD) lungs. Large animal (in vivo) transplantation models are required to validate ongoing in vitro research findings. Anatomic and physiologic differences between humans and pigs pose significant technical and anesthetic challenges. An easily reproducible transplant model would permit the&#160;in vivo&#160;validation of current ESLP strategies and the preclinical evaluation of various interventions designed to improve donor lung function. This protocol describes a porcine model of orthotopic left lung allotransplantation. This includes anesthetic and surgical techniques, a customized surgical checklist, troubleshooting, modifications, and the benefits and limitations of the approach.

This protocol describes a juvenile porcine model of orthotopic left lung allotransplantation designed for use with ESLP research. Focus is made on anesthetic and surgical techniques, as well as critical steps and troubleshooting.

Lung transplantation is the gold-standard treatment for end-stage lung disease, with over 4,600 lung transplantations performed worldwide annually. ...