We would like to thank Robin Nye (Tufts Medical Center), Tomoya Uchimura and Dana Cairns (Tufts University) for providing help with synovial fluid storage and centrifugation. This work was funded by the NIH (1R01AR059106-01A1) for L.Z.

A 3D system for culturing human articular chondrocytes in synovial fluid
In this work, we encapsulated human articular chondrocytes in alginate beads using a modified manufacture-suggested encapsulation protocol (Lonza, and 31). Using these 3D constructs, we have developed a system for culturing cells in a culture medium containing varied percentages of human synovial fluid and have assessed these 3D constructs for cartilage gene expression.
1. Prepare human articular chondrocytes (HAC) for three-dimensional (3D) encapsulation
<ol>
	<li>Thaw a vial (1 ml) of human articular chondrocytes (HAC) (Lonza) (Passage 2) in 37&deg;C water bath for 1 min.</li>
	<li>Mix with 1ml of chondrocyte growth media (Lonza) and centrifuge at 3000 rpm for 3-5 min to collect the cells. Discard the supernatant.</li>
	<li>Resuspend cell pellet in chondrocyte growth media (Lonza).</li>
	<li>Plate cells in a 10 cm tissue culture plate (BD Biosciences), and culture in chondrocyte growth media (Lonza) until the cells are confluent. HACs should be used at a passage number no higher than 3 or 4 (P3 or P4).</li>
	<li>Wash HACs on the plate with 155mM NaCl instead of the standard PBS, followed by trypsinzation to collect cells for alginate bead encapsulation. Once cells are detached, spin down the cells at 3000rpm for 5min. The cells are now ready for 3D encapsulation.</li>
</ol>
2. Encapsulate HACs into 3D beads
Resuspend the HACs in 1.2% alginate solution (Sigma) at a density of 8x105cells/ml. Cell numbers were determined prior to encapsulation, using a standard cell counter. It is very important to mix well to ensure even distribution of the cells in the beads.
<ol>
	<li>Pipette the HAC/Alginate solution mixture into a 12 ml syringe attached to a 22-gauge needle (Tyco healthcare, Inc.).</li>
	<li>Meanwhile, prepare a 50 mL beaker with 102 mM CaCl2 at a volume 5 times that of the HAC/aginate solution. Place a stir bar inside the beaker and stir the 102 mM CaCl2 solution slowly (at approximately 150 rpm).</li>
	<li>Hold the syringe tip about 6 inches above the surface of the CaCl2 solution and add the HAC/alginate mixture into the CaCl2 solution dropwise. In general, the resulting alginate beads are 2mm in diameter with an encapsulation density of approximately 104 cells/bead. Note: The height of the syringe over the CaCl2 solution is important. Shorter distance will result in tear-drop shaped instead of spherical shaped beads, causing uneven mechanical integrity and cell encapsulation.</li>
	<li>Let the beads stir in the CaCl2 solution for 20-25 min. While other alginate encapsulation protocols indicate a much shorter incubation time of 10min, we found that longer incubation time with the CaCl2 solution enhanced the integrity of the beads.</li>
	<li>Remove the CaCl2 solution, wash the beads 2-3 times in 2-3 volumes of NaCl, and then once in chondrocyte differentiation medium (Lonza). While other alginate bead encapsulation protocols involve using a filter for the above washing procedures, we found that the alginate beads often become trapped in the filter and dry out, thus reducing the efficiency of encapsulation. We found it most efficient to allow the beads to settle to the bottom of the beaker before discarding the solution.</li>
	<li>Use a standard spatula to transfer the beads into culture dishes. We usually culture 12 beads per 3 cm well for 2 days in chondrocyte growth medium to allow chondrocytes to adjust to the encapsulation process in the medium they were grown in before switching to chondrocyte differentiation medium (Lonza) with synovial fluid.</li>
</ol>
3. Culture chondrocytes in synovial fluid culture medium
<ol>
	<li>Fresh synovial fluid can be obtained from an outpatient clinic (We obtained synovial fluid from Tufts Medical Center). The synovial fluid can be transferred in 15ml falcon tubes to the laboratory, and immediately centrifuged at 3000 rpm for 15min to remove cell debris. Aliquot cell-free synovial fluid into 1.5 mL microcentrifuge tubes, to avoid repeated freeze-thawing. Supernatant can be stored at -80&deg;C until use.</li>
	<li>Prior to culturing, mix the synovial fluid with chondrocyte differentiation medium (CDM, Lonza) at varying volumetric ratios, with a constant concentration of 100mM ascorbic acid and 9 mM CaCl2 (this trace amount of CaCl2 is to ensure the integrity of the alginate beads).</li>
	<li>Keep the plate on a rocking platform in a 37&deg;C incubator (rocking frequency: about 75 times/min) to help nutrient distribution within the alginate beads, and to reduce clumping of the beads. This is especially important as we culture these chondrocytes for an extended period of time (up to 4 weeks). Note: While chondrocyte growth and differentiation media (Lonza) contain two commonly used antibiotics gentamycin and amphotericin, we did not supplement any antibiotics when we used different percentage of synovial fluid for chondrocyte culturing. No contamination was ever observed.</li>
	<li>Change media mixtures every 2-3 days. The viscosity of synovial fluid has been a major hurdle in culturing chondrocytes encapsulated in alginate beads during long-term cultures. We found it most effective to dilute synovial fluid-supplemented medium with 102mM CaCl2 (50% V/V), which also strengthens the integrity of the alginate beads. In this way, the medium can slowly be removed with a pipet, without damaging the beads.</li>
</ol>
4. Harvest HACs in alginate beads for gene expression analysis
Special care must be taken when harvesting the HACs from the alginate beads for gene expression analysis.
<ol>
	<li>Wash the alginate beads 3 times in 102 mM CaCl2 for about 5 min each time.</li>
	<li>Retrieve the chondrocytes by adding 55 mM NaCitrate at a volume 4-5 times that of the beads. It is important that the alginate beads are totally immersed in the NaCitrate solution. Shake or rock for 20-30 min.</li>
	<li>Spin down the cells and discard the supernatant.</li>
	<li>For RT-PCR analysis, resuspend the cell pellet in cell lysis buffer (Qiagen RNA isolation kit), and proceed with RNA purification.</li>
</ol>
5. Fix HACs in alginate beads for histological analysis
Special care has to be taken to harvest the HACs from the 3D beads for histological analysis.
<ol>
	<li>Wash the alginate beads 3 times in 102 mM CaCl2 for about 5 min each time. To completely wash away the viscous synovial fluid, we found it most effective to wash with chondrocyte differentiation medium (Lonza) overnight, rocking in a 37&deg;C incubator (rocking frequency: about 75 times/min). The chondrocyte growth medium was used to ensure chondrocyte survival in this prolonged wash and to allow maximum penetration of the fixing agent.</li>
	<li>Fix the beads in 70% ethanol overnight, and proceed with histological analysis. To perform Dapi staining, incubate alginate beads with Dapi solution (500ng/ml) for 1hr under gentle rocking, and wash for 3 times with 102mM CaCl2 for 15 min each time. Dapi images can then be viewed under a fluorescent microscope. The beads can also be sectioned for alcian blue and H&amp;E staining.</li>
</ol>
6. Representative Results
Our 3D culturing method for human chondrocytes in high percentages of synovial fluid is depicted in the schematic diagram shown in Fig.1. After human chondrocytes were encapsulated in alginate beads, they were allowed to grow in medium supplemented with varying ratios of synovial fluid. Because of the viscosity of the synovial fluid, it is essential to culture chondrocytes under constant rocking conditions to prevent the clumping of the cartilage constructs and to ensure even distribution of the nutrients. It is also essential to wash the alginate beads extensively before retrieving the chondrocytes, so that the fixing or lysis buffer can penetrate the beads (Fig.1). Bright field (BF) images of chondrocytes in the alginate beads are shown in Fig.2. Dapi staining was performed to confirm usniform distribution of the cells within the beads (Fig. 2). At the end of the 21-day culture period, gene expression analysis was performed by qRT-PCR. The reference gene GAPDH was used for normalization for all PCRs, as it was determined to be one of the most reliable reference genes for qPCR analysis on chondrocytes 32. An example is shown in Fig. 3, where we analyzed the results from human articular chondrocytes cultured in synovial fluid pooled from six patients with osteoarthritis. Consistent with the fact that the chondrocytes from Lonza have been expanded in 2D cultures, which would inevitably lead to de-differentiation 33, we found that Day 0 chondrocytes expressed minimal levels of cartilage matrix genes (Fig. 3). 3D culturing of chondrocytes with chondrocyte differentiation medium (Lonza) or medium supplemented with synovial fluid significantly increased cartilage gene expression of collagen, aggrecan and MMP13, which indicates chondrocyte re-differentiation by Day 21 (Fig.3) 34. Increasing the percentage of synovial fluid in the media resulted in comparable levels of cartilage matrix markers collagen II and aggrecan mRNA expression (Fig.3A and 3B). Furthermore, chondrocytes cultured in 100% synovial fluid even exhibited a decrease in cartilage degrading enzyme MMP13 mRNA expression as compared with those cultured in medium alone (Fig.3C). Interestingly, the expression level of cell death indicator caspase 3 gradually decreased with increasing ratios of synovial fluid, suggesting that synovial fluid culturing has led to decreased apoptosis levels (Fig. 3D). Therefore, our results show that culturing human articular chondrocytes in high levels of synovial fluid in a 3D setting is a feasible technology.
Tables and Figures
<img alt="Figure 1." src="/files/ftp_upload/3587/3587fig1.jpg" /> 
Figure 1. Schematic diagram of the method to culture human articular chondrocytes in high percentages of synovial fluid in 3D alginate beads. First, chondrocytes and alginate solution are mixed. When applied drop-wise to the CaCl2 solution, chondrocytes are immobilized within the crosslinked Ca-alginate hydrogel beads. These 3D constructs are then cultured in the chondrocyte differentiation medium (Lonza) with varying ratios of human synovial fluid. After 21 days of culturing under a rocking condition, alginate beads containing cells are washed extensively after which the cells are retrieved for gene expression analysis.
<img alt="Figure 2." src="/files/ftp_upload/3587/3587fig2.jpg" /> 
Figure 2. Bright field (BF) and Dapi images of human articular chondrocytes encapsulated cultures with 0%, 30%, 50%, 70% and 100% synovial fluid. Chondrocytes were spherical in shape in all culture conditions. Images of bright field (BF) and Dapi were overlaid to confirm the location and distribution of chondrocytes. Insets, magnified images. Arrowheads, colocalization of chondrocytes in BF and Dapi staining images.
<img alt="Figure 3." src="/files/ftp_upload/3587/3587fig3.jpg" /> 
Figure 3. qRT-PCR analysis of encapsulated human articular chondrocytes at day 0 (D0) an after 21 days of culturing (D21) in medium supplemented with varying ratios of synovial fluid (SF) (0%, 30%, 50%, 70% and 100%). Results of four independent samples are shown here. GAPDH was used as internal reference for all PCRs. A. Collagen II mRNA expression. B. Aggrecan mRNA expression. C. MMP13 mRNA expression. D. Caspase 3 mRNA expression. Statistical significance was assessed for Day 0 samples and Day 21 samples of 0% and 100% synovial fluid (SF) culturing, using INSTAT software. * denotes P&lt;0.05.

<ol>
	<li>Centers for Disease Control and P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Projected+state-specific+increases+in+self-reported+doctor-diagnosed+arthritis+and+arthritis-attributable+activity+limitations--United+States,+2005-2030.">Projected state-specific increases in self-reported doctor-diagnosed arthritis and arthritis-attributable activity limitations--United States, 2005-2030.</a> MMWR. Morb. Mortal. Wkly. Rep. 56, 423-425 (2007).</li><li>Theis, K. A., Murphy, L., Hootman, J. M., Helmick, C. G., Yelin, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prevalence+and+correlates+of+arthritis-attributable+work+limitation+in+the+US+population+among+persons+ages+18-64:+2002+National+Health+Interview+Survey+Data.">Prevalence and correlates of arthritis-attributable work limitation in the US population among persons ages 18-64: 2002 National Health Interview Survey Data.</a> Arthritis Rheum. 57, 355-363 (2007).</li><li>Chung, C., Burdick, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Engineering+cartilage+tissue.">Engineering cartilage tissue.</a> Adv. Drug. Deliv. Rev. 60, 243-262 (2008).</li><li>Glowacki, J. <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+engineering+of+cartilage.">In vitro engineering of cartilage.</a> J. Rehabil. Res. Dev. 37, 171-177 (2000).</li><li>Chokalingam, K., Hunter, S. A., Gooch, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=3D-In+vitro+Effects+of+Compression+and+Time+in+Culture+on+Aggregate+Modulus+and+on+Gene+Expression+and+Protein+content+of+Collagen+Type+II+in+Murine+Chondrocytes.">3D-In vitro Effects of Compression and Time in Culture on Aggregate Modulus and on Gene Expression and Protein content of Collagen Type II in Murine Chondrocytes.</a> Tissue Eng. Part A. , (2009).</li><li>Butler, D. L., Goldstein, S. A., Guilak, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+tissue+engineering:+the+role+of+biomechanics.">Functional tissue engineering: the role of biomechanics.</a> J. Biomech. Eng. 122, 570-575 (2000).</li><li>Goldring, M. B., Goldring, S. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Osteoarthritis.">Osteoarthritis.</a> J. Cell. Physiol. 213, 626-634 (2007).</li><li>Zvaifler, N. J., Firestein, G. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cytokines+in+chronic+inflammatory+synovitis.">Cytokines in chronic inflammatory synovitis.</a> Scand. J. Rheumatol. Suppl. 76, 203-210 (1988).</li><li>Rhee, D. K., Marcelino, J., Baker, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+secreted+glycoprotein+lubricin+protects+cartilage+surfaces+and+inhibits+synovial+cell+overgrowth.">The secreted glycoprotein lubricin protects cartilage surfaces and inhibits synovial cell overgrowth.</a> J. Clin. Invest. 115, 622-631 (2005).</li><li>Campo, G. M., Avenoso, A., Nastasi, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hyaluronan+reduces+inflammation+in+experimental+arthritis+by+modulating+TLR-2+and+TLR-4+cartilage+expression.">Hyaluronan reduces inflammation in experimental arthritis by modulating TLR-2 and TLR-4 cartilage expression.</a> Biochim. Biophys. Acta. , (2011).</li><li>van de Lest, C. H., van den Hoogen, B. M., van Weeren, P. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Loading-induced+changes+in+synovial+fluid+affect+cartilage+metabolism.">Loading-induced changes in synovial fluid affect cartilage metabolism.</a> Biorheology. 37, 45-55 (2000).</li><li>Saxne, T., Heinegard, D., Wollheim, F. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+arthritic+synovial+fluid+influences+proteoglycan+biosynthesis+and+degradation+in+organ+culture+of+bovine+nasal+cartilage.">Human arthritic synovial fluid influences proteoglycan biosynthesis and degradation in organ culture of bovine nasal cartilage.</a> Coll. Relat. Res. 8, 233-247 (1988).</li><li>Lee, D. A., Salih, V., Stockton, E. F., Stanton, J. S., Bentley, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+normal+synovial+fluid+on+the+metabolism+of+articular+chondrocytes+in+vitro.">Effect of normal synovial fluid on the metabolism of articular chondrocytes in vitro.</a> Clin. Orthop. Relat. Res. , 228-238 (1997).</li><li>Schalkwijk, J., Joosten, L. A., van den Berg, W. B., van de Putte, L. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chondrocyte+nonresponsiveness+to+insulin-like+growth+factor+1+in+experimental+arthritis.">Chondrocyte nonresponsiveness to insulin-like growth factor 1 in experimental arthritis.</a> Arthritis Rheum. 32, 894-900 (1989).</li><li>Schalkwijk, J., Joosten, L. A., van den Berg, W. B., van Wyk, J. J., van de Putte, L. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insulin-like+growth+factor+stimulation+of+chondrocyte+proteoglycan+synthesis+by+human+synovial+fluid.">Insulin-like growth factor stimulation of chondrocyte proteoglycan synthesis by human synovial fluid.</a> Arthritis Rheum. 32, 66-71 (1989).</li><li>Joosten, L. A., Schalkwijk, J., van den Berg, W. B., van de Putte, L. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chondrocyte+unresponsiveness+to+insulin-like+growth+factor-1.+A+novel+pathogenetic+mechanisms+for+cartilage+destruction+in+experimental+arthritis.">Chondrocyte unresponsiveness to insulin-like growth factor-1. A novel pathogenetic mechanisms for cartilage destruction in experimental arthritis.</a> Agents Actions. 26, 193-195 (1989).</li><li>Schuerwegh, A. J., Dombrecht, E. J., Stevens, W. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synovial+fluid+and+peripheral+blood+immune+complexes+of+patients+with+rheumatoid+arthritis+induce+apoptosis+in+cytokine-activated+chondrocytes.">Synovial fluid and peripheral blood immune complexes of patients with rheumatoid arthritis induce apoptosis in cytokine-activated chondrocytes.</a> Rheumatol. Int. 27, 901-909 (2007).</li><li>Hegewald, A. A., Ringe, J., Bartel, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hyaluronic+acid+and+autologous+synovial+fluid+induce+chondrogenic+differentiation+of+equine+mesenchymal+stem+cells:+a+preliminary+study.">Hyaluronic acid and autologous synovial fluid induce chondrogenic differentiation of equine mesenchymal stem cells: a preliminary study.</a> Tissue Cell. 36, 431-438 (2004).</li><li>Xu, Q. R., Dong, Y. H., Chen, S. L., Bao, C. D., Du, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Degeneration+of+normal+articular+cartilage+induced+by+late+phase+osteoarthritic+synovial+fluid+in+beagle+dogs.">Degeneration of normal articular cartilage induced by late phase osteoarthritic synovial fluid in beagle dogs.</a> Tissue Cell. 41, 13-22 (2009).</li><li>Kruger, J. P., Endres, M., Neumann, K., Haupl, T., Erggelet, C., Kaps, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chondrogenic+differentiation+of+human+subchondral+progenitor+cells+is+impaired+by+rheumatoid+arthritis+synovial+fluid.">Chondrogenic differentiation of human subchondral progenitor cells is impaired by rheumatoid arthritis synovial fluid.</a> J. Orthop. Res. 28, 819-827 (2010).</li><li>Steinhagen, J., Bruns, J., Niggemeyer, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Perfusion+culture+system:+Synovial+fibroblasts+modulate+articular+chondrocyte+matrix+synthesis+in+vitro.">Perfusion culture system: Synovial fibroblasts modulate articular chondrocyte matrix synthesis in vitro.</a> Tissue Cell. 42, 151-157 (2010).</li><li>Yang, K. G., Saris, D. B., Verbout, A. J., Creemers, L. B., Dhert, W. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effect+of+synovial+fluid+from+injured+knee+joints+on+in+vitro+chondrogenesis.">The effect of synovial fluid from injured knee joints on in vitro chondrogenesis.</a> Tissue Eng. 12, 2957-2964 (2006).</li><li>Skoog, V., Widenfalk, B., Ohlsen, L., Wasteson, 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+effect+of+growth+factors+and+synovial+fluid+on+chondrogenesis+in+perichondrium.">The effect of growth factors and synovial fluid on chondrogenesis in perichondrium.</a> Scand. J. Plast. Reconstr. Surg. Hand. Surg.. 24, 89-95 (1990).</li><li>Nuver-Zwart, I., Schalkwijk, J., Joosten, L. A., van den Berg, W. B., van de Putte, L. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+synovial+fluid+and+synovial+fluid+cells+on+chondrocyte+metabolism+in+short+term+tissue+culture.">Effects of synovial fluid and synovial fluid cells on chondrocyte metabolism in short term tissue culture.</a> J. Rheumatol. 15, 210-216 (1988).</li><li>Beekhuizen, M., Bastiaansen-Jenniskens, Y. M., Koevoet, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Osteoarthritic+synovial+tissue+inhibits+proteoglycan+production+in+human+osteoarthritic+cartilage;+Establishment+and+characterisation+of+a+long-term+coculture.">Osteoarthritic synovial tissue inhibits proteoglycan production in human osteoarthritic cartilage; Establishment and characterisation of a long-term coculture.</a> Arthritis Rheum. , (2011).</li><li>Rodrigo, J. J., Steadman, J. R., Syftestad, G., Benton, H., Silliman, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+human+knee+synovial+fluid+on+chondrogenesis+in+vitro.">Effects of human knee synovial fluid on chondrogenesis in vitro.</a> Am. J. Knee. Surg. 8, 124-129 (1995).</li><li>van den Hoogen, B. M., van de Lest, C. H., van Weeren, P. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Loading-induced+changes+in+synovial+fluid+affect+cartilage+metabolism.">Loading-induced changes in synovial fluid affect cartilage metabolism.</a> Br. J. Rheumatol. 37, 671-676 (1998).</li><li>Webb, G. R., Westacott, C. I., Elson, 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=Osteoarthritic+synovial+fluid+and+synovium+supernatants+up-regulate+tumor+necrosis+factor+receptors+on+human+articular+chondrocytes.">Osteoarthritic synovial fluid and synovium supernatants up-regulate tumor necrosis factor receptors on human articular chondrocytes.</a> Osteoarthritis Cartilage. 6, 167-176 (1998).</li><li>Kook, S. H., Son, Y. O., Lee, K. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hypoxia+affects+positively+the+proliferation+of+bovine+satellite+cells+and+their+myogenic+differentiation+through+up-regulation+of+MyoD.">Hypoxia affects positively the proliferation of bovine satellite cells and their myogenic differentiation through up-regulation of MyoD.</a> Cell. Biol. Int. 32, 871-878 (2008).</li><li>Knobloch, T. J., Madhavan, S., Nam, J., Agarwal, S., Agarwal, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulation+of+chondrocytic+gene+expression+by+biomechanical+signals.">Regulation of chondrocytic gene expression by biomechanical signals.</a> Crit. Rev. Eukaryot. Gene. Expr. 18, 139-150 (2008).</li><li>Guo, J. F., Jourdian, G. W., MacCallum, D. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Culture+and+growth+characteristics+of+chondrocytes+encapsulated+in+alginate+beads.">Culture and growth characteristics of chondrocytes encapsulated in alginate beads.</a> Connect. Tissue. Res. 19, 277-297 (1989).</li><li>Toegel, S., Huang, W., Piana, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Selection+of+reliable+reference+genes+for+qPCR+studies+on+chondroprotective+action.">Selection of reliable reference genes for qPCR studies on chondroprotective action.</a> BMC. Mol. Biol. 8, 13-13 (2007).</li><li>Lin, Z., Fitzgerald, J. B., Xu, J. <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+profiles+of+human+chondrocytes+during+passaged+monolayer+cultivation.">Gene expression profiles of human chondrocytes during passaged monolayer cultivation.</a> J. Orthop. Res. 26, 1230-1237 (2008).</li><li>Goessler, U. R., Bieback, K., Bugert, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+chondrocytes+differentially+express+matrix+modulators+during+in+vitro+expansion+for+tissue+engineering.">Human chondrocytes differentially express matrix modulators during in vitro expansion for tissue engineering.</a> Int. J. Mol. Med. 16, 509-515 (2005).</li><li>Anat, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> 121, 107-118 (1976).</li></ol>

We have nothing to disclose.

In this report, we developed a method that allows for the culture of human articular chondrocytes in a 3D environment in medium that contains high concentrations of human synovial fluid. Synovial fluid is one of the major components that constitute the natural environment in the joint cavity, where articular chondrocytes reside. However, the viscosity of the synovial fluid has been a major challenge for three-dimensional long-term culturing of chondrocytes. To overcome the challenge of maintaining even nutrient distribut...

Table of specific reagents and equipment: 
 <table border="1">
 <tr>
 <th>Name of the Reagent</th>
 <th>Company</th>
 <th>Catalogue Number</th>
 <th>Comments</th>
 </tr>
 <tr>
 <td>Alginate (Alginic Acid sodium salt)</td>
 <td>Sigma</td>
 <td>A2158-250G</td>
 <td>2.4% solution stored at 40&deg;C</td>
 </tr>
 <tr>
 <td>Calcium Chloride Dihydrate, Granular</td>
 <td>J.T. Baker</td>
 <td>A19339</td>
 <td></td>
 </tr>
 <tr>
 <td width="239" rowspan="2" >Chondrogenic Growth media</td>
 <td width="254" rowspan="2" >Lonza</td>
 <td width="182" >CC-3156 (base media)</td>
 <td width="141" rowspan="2" >&nbsp;</td>
 </tr>
 <tr>
 <td width="182" >CC-4409 (supplement)</td>
 </tr>
 <tr>
 <td width="239" rowspan="2" >Chondrogenic Differentiation Media</td>
 <td width="254" rowspan="2" >Lonza</td>
 <td width="182" >CC-3226 (base media)</td>
 <td width="141" rowspan="2" >&nbsp;</td>
 </tr>
 <tr>
 <td width="182" >CC-4408 (supplement)</td>
 </tr>
 <tr>
 <td>Human articular chondrocytes</td>
 <td>Lonza</td>
 <td >CC-2550</td>
 <td></td>
 </tr>
 <tr>
 <td>Dapi (4&prime;,6-Diamidino-2-phenylindole dihydrochloride)</td>
 <td>Sigma-Aldrich</td>
 <td >D9542</td>
 <td></td>
 </tr>
 <tr>
 <td>RNeasy mini kit (for RNA extraction)</td>
 <td>Qiagen</td>
 <td >74104</td>
 <td></td>
 </tr>
 <tr>
 <td>PCR reagents: SYBR-green</td>
 <td>Quanta</td>
 <td >95053-500</td>
 <td></td>
 </tr>
 <tr>
 <td>12 ml syringe</td>
 <td>Tyco-Kendall-Monoject</td>
 <td >512852</td>
 <td></td>
 </tr>
 <tr>
 <td>22-Gague Hypodermic Needle </td>
 <td>Tyco-Kendall-Monoject</td>
 <td >8881</td>
 <td></td>
 </tr>
 <tr>
 <td>Microscope</td>
 <td>Olympus</td>
 <td >IX71</td>
 <td></td>
 </tr>
 <tr>
 <td>Platform rocker </td>
 <td>Thermoscientific thermolyne</td>
 <td >Vari-mix</td>
 <td></td>
 </tr>
 <tr>
 <td>&nbsp;</td>
 <td>&nbsp;</td>
 <td >&nbsp;</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Primers sequences</td>
 <td></td>
 <td ></td>
 <td></td>
 </tr>
 <tr>
 <td>Collagen IIa-forward</td>
 <td>5'-TTC ATC CCA CCC TCT CAC AGT-3'</td>
 <td ></td>
 <td></td>
 </tr>
 <tr>
 <td>Collagen IIa-reverse</td>
 <td>5'-CCTCTGCCTTGACCCGAA-3'</td>
 <td ></td>
 <td></td>
 </tr>
 <tr>
 <td>MMP13-forward</td>
 <td>5'-TGT GCC CTT CTT CAC ACA GAC ACT-3'</td>
 <td ></td>
 <td></td>
 </tr>
 <tr>
 <td>MMP13-reverse</td>
 <td>5'-GAG AGC AGA CTT TGA GTC ATT GCC-3'</td>
 <td ></td>
 <td></td>
 </tr>
 <tr>
 <td>Caspase 3-forward</td>
 <td>5'-TCA TTA TTC AGG CCT GCC GTG GTA-3'</td>
 <td ></td>
 <td></td>
 </tr>
 <tr>
 <td>Caspase 3-reverse</td>
 <td>5'-TGG ATG AAC CAG GAG CCA TCC TTT -3'</td>
 <td ></td>
 <td></td>
 </tr>
 </table>

a 3d system for culturing human articular chondrocytes in synovial fluid

Cartilage destruction is a central pathological feature of osteoarthritis, a leading cause of disability in the US. Cartilage in the adult does not regenerate very efficiently in vivo; and as a result, osteoarthritis leads to irreversible cartilage loss and is accompanied by chronic pain and immobility 1,2. Cartilage tissue engineering offers promising potential to regenerate and restore tissue function. This technology typically involves seeding chondrocytes into natural or synthetic scaffolds and culturing the resulting 3D construct in a balanced medium over a period of time with a goal of engineering a biochemically and biomechanically mature tissue that can be transplanted into a defect site in vivo 3-6. Achieving an optimal condition for chondrocyte growth and matrix deposition is essential for the success of cartilage tissue engineering. 
 In the native joint cavity, cartilage at the articular surface of the bone is bathed in synovial fluid. This clear and viscous fluid provides nutrients to the avascular articular cartilage and contains growth factors, cytokines and enzymes that are important for chondrocyte metabolism 7,8. Furthermore, synovial fluid facilitates low-friction movement between cartilaginous surfaces mainly through secreting two key components, hyaluronan and lubricin 9 10. In contrast, tissue engineered cartilage is most often cultured in artificial media. While these media are likely able to provide more defined conditions for studying chondrocyte metabolism, synovial fluid most accurately reflects the natural environment of which articular chondrocytes reside in.
 Indeed, synovial fluid has the advantage of being easy to obtain and store, and can often be regularly replenished by the body. Several groups have supplemented the culture medium with synovial fluid in growing human, bovine, rabbit and dog chondrocytes, but mostly used only low levels of synovial fluid (below 20&#37;) 11-25. While chicken, horse and human chondrocytes have been cultured in the medium with higher percentage of synovial fluid, these culture systems were two-dimensional 26-28. Here we present our method of culturing human articular chondrocytes in a 3D system with a high percentage of synovial fluid (up to 100&#37;) over a period of 21 days. In doing so, we overcame a major hurdle presented by the high viscosity of the synovial fluid. This system provides the possibility of studying human chondrocytes in synovial fluid in a 3D setting, which can be further combined with two other important factors (oxygen tension and mechanical loading) 29,30 that constitute the natural environment for cartilage to mimic the natural milieu for cartilage growth. Furthermore, This system may also be used for assaying synovial fluid activity on chondrocytes and provide a platform for developing cartilage regeneration technologies and therapeutic options for arthritis.

Watch this Scientific Journal Video about A 3D System for Culturing Human Articular Chondrocytes in Synovial Fluid at JoVE.com

A 3D System for Culturing Human Articular Chondrocytes in Synovial Fluid

A 3D system of culturing human articular chondrocytes in high levels of synovial fluid is described. Synovial fluid reflects the most natural microenvironment for articular cartilage, and can be easily obtained and stored. This system thus can be used for studying cartilage regeneration and for screening therapeutics for treating arthritis.

Cartilage destruction is a central pathological feature of osteoarthritis, a leading cause of disability in the US. Cartilage in the adult does not ...

a-3d-system-for-culturing-human-articular-chondrocytes-synovial

Research

JoVE Journal

Biology

20.7K Views.  Tufts University School of Medicine. A 3D system of culturing human articular chondrocytes in high levels of synovial fluid is described. Synovial fluid reflects the most natural microenvironment for articular cartilage, and can be easily obtained and stored. This system thus can be used for studying cartilage regeneration and for screening therapeutics for treating arthritis.

Video: A 3D System for Culturing Human Articular Chondrocytes in Synovial Fluid

A System for Culturing Iris Pigment Epithelial Cells to Study Lens Regeneration in Newt

Salamanders like newt and axolotl possess the ability to regenerate many of its lost body parts such as limbs, the tail with spinal cord, eye, brain, heart, the jaw 1. Specifically, newts are unique for its lens regeneration capability. Upon lens removal, IPE cells of the dorsal iris transdifferentiate to lens cells and eventually form a new lens in about a month 2,3. This property of regeneration is never exhibited by the ventral iris cells. The regeneration potential of the iris cells can be studied by making transplants of the in vitro cultured IPE cells. For the culture, the dorsal and ventral iris cells are first isolated from the eye and cultured separately for a time period of 2 weeks (Figure 1). These cultured cells are reaggregated and implanted back to the newt eye. Past studies have shown that the dorsal reaggregate maintains its lens forming capacity whereas the ventral aggregate does not form a lens, recapitulating, thus the in vivo process (Figure 2) 4,5. This system of determining regeneration potential of dorsal and ventral iris cells is very useful in studying the role of genes and proteins involved in lens regeneration.

In newt, the lens regenerates always from the dorsal iris by transdifferentiation of the iris pigmented epithelial cells (IPEs). Here we describe a procedure to culture dorsal and ventral newt IPE cells and their implantation to the newt eye. The implanted cells are then studied by tissue sectioning and immunohistochemistry.

Salamanders like newt and axolotl possess the ability to regenerate many of its lost body parts such as limbs, the tail with spinal cord, eye, brain, ...

Efficient Derivation of Human Cardiac Precursors and Cardiomyocytes from Pluripotent Human Embryonic Stem Cells with Small Molecule Induction

To date, the lack of a suitable human cardiac cell source has been the major setback in regenerating the human myocardium, either by cell-based transplantation or by cardiac tissue engineering1-3. Cardiomyocytes become terminally-differentiated soon after birth and lose their ability to proliferate. There is no evidence that stem/progenitor cells derived from other sources, such as the bone marrow or the cord blood, are able to give rise to the contractile heart muscle cells following transplantation into the heart1-3. The need to regenerate or repair the damaged heart muscle has not been met by adult stem cell therapy, either endogenous or via cell delivery1-3. The genetically stable human embryonic stem cells (hESCs) have unlimited expansion ability and unrestricted plasticity, proffering a pluripotent reservoir for in vitro derivation of large supplies of human somatic cells that are restricted to the lineage in need of repair and regeneration4,5. Due to the prevalence of cardiovascular disease worldwide and acute shortage of donor organs, there is intense interest in developing hESC-based therapies as an alternative approach. However, how to channel the wide differentiation potential of pluripotent hESCs efficiently and predictably to a desired phenotype has been a major challenge for both developmental study and clinical translation. Conventional approaches rely on multi-lineage inclination of pluripotent cells through spontaneous germ layer differentiation, resulting in inefficient and uncontrollable lineage-commitment that is often followed by phenotypic heterogeneity and instability, hence, a high risk of tumorigenicity6-8 (see a schematic in Fig. 1A). In addition, undefined foreign/animal biological supplements and/or feeders that have typically been used for the isolation, expansion, and differentiation of hESCs may make direct use of such cell-specialized grafts in patients problematic9-11. To overcome these obstacles, we have resolved the elements of a defined culture system necessary and sufficient for sustaining the epiblast pluripotence of hESCs, serving as a platform for de novo derivation of clinically-suitable hESCs and effectively directing such hESCs uniformly towards clinically-relevant lineages by small molecules12 (see a schematic in Fig. 1B). After screening a variety of small molecules and growth factors, we found that such defined conditions rendered nicotinamide (NAM) sufficient to induce the specification of cardiomesoderm direct from pluripotent hESCs that further progressed to cardioblasts that generated human beating cardiomyocytes with high efficiency (Fig. 2). We defined conditions for induction of cardioblasts direct from pluripotent hESCs without an intervening multi-lineage embryoid body stage, enabling well-controlled efficient derivation of a large supply of human cardiac cells across the spectrum of developmental stages for cell-based therapeutics.

We have established a protocol for induction of cardioblasts direct from pluripotent human embryonic stem cells maintained under defined conditions with small molecules, which enables derivation of a large supply of human cardiac progenitors and functional cardiomyocytes for cardiovascular repair.

To date, the lack of a suitable human cardiac cell source has been the major setback in regenerating the human myocardium, either by cell-based ...

A System for ex vivo Culturing of Embryonic Pancreas

The pancreas controls vital functions of our body, including the production of digestive enzymes and regulation of blood sugar levels1. Although in the past decade many studies have contributed to a solid foundation for understanding pancreatic organogenesis, important gaps persist in our knowledge of early pancreas formation2. A complete understanding of these early events will provide insight into the development of this organ, but also into incurable diseases that target the pancreas, such as diabetes or pancreatic cancer. Finally, this information will generate a blueprint for developing cell-replacement therapies in the context of diabetes.
 During embryogenesis, the pancreas originates from distinct embryonic outgrowths of the dorsal and ventral foregut endoderm at embryonic day (E) 9.5 in the mouse embryo3,4. Both outgrowths evaginate into the surrounding mesenchyme as solid epithelial buds, which undergo proliferation, branching and differentiation to generate a fully mature organ2,5,6. Recent evidences have suggested that growth and differentiation of pancreatic cell lineages, including the insulin-producing &beta;-cells, depends on proper tissue-architecture, epithelial remodeling and cell positioning within the branching pancreatic epithelium7,8. However, how branching morphogenesis occurs and is coordinated with proliferation and differentiation in the pancreas is largely unknown. This is in part due to the fact that current knowledge about these developmental processes has relied almost exclusively on analysis of fixed specimens, while morphogenetic events are highly dynamic.
 Here, we report a method for dissecting and culturing mouse embryonic pancreatic buds ex vivo on glass bottom dishes, which allow direct visualization of the developing pancreas (Figure 1). This culture system is ideally devised for confocal laser scanning microscopy and, in particular, live-cell imaging. Pancreatic explants can be prepared not only from wild-type mouse embryos, but also from genetically engineered mouse strains (e.g. transgenic or knockout), allowing real-time studies of mutant phenotypes. Moreover, this ex vivo culture system is valuable to study the effects of chemical compounds on pancreatic development, enabling to obtain quantitative data about proliferation and growth, elongation, branching, tubulogenesis and differentiation. In conclusion, the development of an ex vivo pancreatic explant culture method combined with high-resolution imaging provides a strong platform for observing morphogenetic and differentiation events as they occur within the developing mouse embryo.

A System for ex vivo Culturing of Embryonic Pancreas

Here, we describe a method for isolation, culture and manipulation of mouse embryonic pancreas. This represents an excellent ex vivo system for studying various aspects of pancreatic development, including morphogenesis, differentiation and growth. Pancreatic bud explants can be cultured for several days and used in a range of different applications, including whole-mount immunofluorescence and live imaging.

The pancreas controls vital functions of our body,  including the production of digestive enzymes and regulation of blood sugar  levels1. Although in the ...

Analysis of Gene Function and Visualization of Cilia-Generated Fluid Flow in Kupffer's Vesicle

Internal organs such as the heart, brain, and gut develop left-right (LR) asymmetries that are critical for their normal functions1. Motile cilia are involved in establishing LR asymmetry in vertebrate embryos, including mouse, frog, and zebrafish2-6. These 'LR cilia' generate asymmetric fluid flow that is necessary to trigger a conserved asymmetric Nodal (TGF-&beta; superfamily) signaling cascade in the left lateral plate mesoderm, which is thought to provide LR patterning information for developing organs7. Thus, to understand mechanisms underlying LR patterning, it is essential to identify genes that regulate the organization of LR ciliated cells, the motility and length of LR cilia and their ability to generate robust asymmetric flow.
In the zebrafish embryo, LR cilia are located in Kupffer's vesicle (KV)2,4,5. KV is comprised of a single layer of monociliated epithelial cells that enclose a fluid-filled lumen. Fate mapping has shown that KV is derived from a group of ~20-30 cells known as dorsal forerunner cells (DFCs) that migrate at the dorsal blastoderm margin during epiboly stages8,9. During early somite stages, DFCs cluster and differentiate into ciliated epithelial cells to form KV in the tailbud of the embryo10,11. The ability to identify and track DFCs&mdash;in combination with optical transparency and rapid development of the zebrafish embryo&mdash;make zebrafish KV an excellent model system to study LR ciliated cells.
Interestingly, progenitors of the DFC/KV cell lineage retain cytoplasmic bridges between the yolk cell up to 4 hr post-fertilization (hpf), whereas cytoplasmic bridges between the yolk cell and other embryonic cells close after 2 hpf8. Taking advantage of these cytoplasmic bridges, we developed a stage-specific injection strategy to deliver morpholino oligonucleotides (MO) exclusively to DFCs and knockdown the function of a targeted gene in these cells12. This technique creates chimeric embryos in which gene function is knocked down in the DFC/KV lineage developing in the context of a wild-type embryo. To analyze asymmetric fluid flow in KV, we inject fluorescent microbeads into the KV lumen and record bead movement using videomicroscopy2. Fluid flow is easily visualized and can be quantified by tracking bead displacement over time.
Here, using the stage-specific DFC-targeted gene knockdown technique and injection of fluorescent microbeads into KV to visualize flow, we present a protocol that provides an effective approach to characterize the role of a particular gene during KV development and function.

Analysis of Gene Function and Visualization of Cilia-Generated Fluid Flow in Kupffer&#039;s Vesicle

Cilia-generated fluid flow in Kupffer&#x2019;s Vesicle (KV) controls left-right patterning of the zebrafish embryo. Here, we describe a technique to modulate gene function specifically in KV cells. In addition, we show how to deliver fluorescent beads into KV to visualize fluid flow.

Internal organs such as the  heart, brain, and gut develop left-right (LR) asymmetries that are critical for  their normal functions1. Motile cilia are ...

Culturing of Human Nasal Epithelial Cells at the Air Liquid Interface

In vitro models using human primary epithelial cells are essential in understanding key functions of the respiratory epithelium in the context of microbial infections or inhaled agents. Direct comparisons of cells obtained from diseased populations allow us to characterize different phenotypes and dissect the underlying mechanisms mediating changes in epithelial cell function. Culturing epithelial cells from the human tracheobronchial region has been well documented, but is limited by the availability of human lung tissue or invasiveness associated with obtaining the bronchial brushes biopsies. Nasal epithelial cells are obtained through much less invasive superficial nasal scrape biopsies and subjects can be biopsied multiple times with no significant side effects. Additionally, the nose is the entry point to the respiratory system and therefore one of the first sites to be exposed to any kind of air-borne stressor, such as microbial agents, pollutants, or allergens. 
Briefly, nasal epithelial cells obtained from human volunteers are expanded on coated tissue culture plates, and then transferred onto cell culture inserts. Upon reaching confluency, cells continue to be cultured at the air-liquid interface (ALI), for several weeks, which creates more physiologically relevant conditions. The ALI culture condition uses defined media leading to a differentiated epithelium that exhibits morphological and functional characteristics similar to the human nasal epithelium, with both ciliated and mucus producing cells. Tissue culture inserts with differentiated nasal epithelial cells can be manipulated in a variety of ways depending on the research questions (treatment with pharmacological agents, transduction with lentiviral vectors, exposure to gases, or infection with microbial agents) and analyzed for numerous different endpoints ranging from cellular and molecular pathways, functional changes, morphology, etc. 
In vitro models of differentiated human nasal epithelial cells will enable investigators to address novel and important research questions by using organotypic experimental models that largely mimic the nasal epithelium in vivo.

Nasal epithelial cells, obtained through superficial scrape biopsy of human volunteers, are expanded and transferred onto tissue culture inserts. Upon reaching confluency, cells are grown at air liquid interface, yielding cultures of ciliated and non-ciliated cells. Differentiated nasal epithelial cell cultures provide viable experimental models for studying the respiratory mucosa.

In vitro models using human primary  epithelial cells are essential in understanding key functions of the respiratory  epithelium in the context of ...

Using Caenorhabditis elegans as a Model System to Study Protein Homeostasis in a Multicellular Organism

The folding and assembly of proteins is essential for protein function, the long-term health of the cell, and longevity of the organism. Historically, the function and regulation of protein folding was studied in vitro, in isolated tissue culture cells and in unicellular organisms. Recent studies have uncovered links between protein homeostasis (proteostasis), metabolism, development, aging, and temperature-sensing. These findings have led to the development of new tools for monitoring protein folding in the model metazoan organism Caenorhabditis elegans. In our laboratory, we combine behavioral assays, imaging and biochemical approaches using temperature-sensitive or naturally occurring metastable proteins as sensors of the folding environment to monitor protein misfolding. Behavioral assays that are associated with the misfolding of a specific protein provide a simple and powerful readout for protein folding, allowing for the fast screening of genes and conditions that modulate folding. Likewise, such misfolding can be associated with protein mislocalization in the cell. Monitoring protein localization can, therefore, highlight changes in cellular folding capacity occurring in different tissues, at various stages of development and in the face of changing conditions. Finally, using biochemical tools ex vivo, we can directly monitor protein stability and conformation. Thus, by combining behavioral assays, imaging and biochemical techniques, we are able to monitor protein misfolding at the resolution of the organism, the cell, and the protein, respectively.

Using Caenorhabditis elegans as a Model System to Study Protein Homeostasis in a Multicellular Organism

To study the relationship between protein homeostasis, stress and aging, we monitored changes in protein folding by following protein dysfunction, protein localization in the cell and protein stability at the organismal, cellular and protein levels, using the genetically tractable metazoan Caenorhabditis elegans as a model system.

The folding and assembly of proteins is essential for protein function, the long-term health of the cell, and longevity of the organism. Historically, the ...

Gap Junctional Intercellular Communication: A Functional Biomarker to Assess Adverse Effects of Toxicants and Toxins, and Health Benefits of Natural Products

This protocol describes a scalpel loading-fluorescent dye transfer (SL-DT) technique that measures intercellular communication through gap junction channels, which is a major intercellular process by which tissue homeostasis is maintained. Interruption of gap junctional intercellular communication (GJIC) by toxicants, toxins, drugs, etc. has been linked to numerous adverse health effects. Many genetic-based human diseases have been linked to mutations in gap junction genes. The SL-DT technique is a simple functional assay for the simultaneous assessment of GJIC in a large population of cells. The assay involves pre-loading cells with a fluorescent dye by briefly perturbing the cell membrane with a scalpel blade through a population of cells. The fluorescent dye is then allowed to traverse through gap junction channels to neighboring cells for a designated time. The assay is then terminated by the addition of formalin to the cells. The spread of the fluorescent dye through a population of cells is assessed with an epifluorescence microscope and the images are analyzed with any number of morphometric software packages that are available, including free software packages found on the public domain. This assay has also been adapted for in vivo studies using tissue slices from various organs from treated animals. Overall, the SL-DT assay can serve a broad range of in vitro pharmacological and toxicological needs, and can be potentially adapted for high throughput set-up systems with automated fluorescence microscopy imaging and analysis to elucidate more samples in a shorter time.

This protocol describes a scalpel loading-fluorescent dye transfer technique that measures intercellular communication through gap junction channels. Gap junctional intercellular communication is a major cellular process by which tissue homeostasis is maintained and disruption of this cell signaling has adverse health effects.

This protocol describes a scalpel loading-fluorescent dye transfer (SL-DT) technique that measures intercellular communication through gap junction ...

The Assembly and Application of 'Shear Rings': A Novel Endothelial Model for Orbital, Unidirectional and Periodic Fluid Flow and Shear Stress

Deviations from normal levels and patterns of vascular fluid shear play important roles in vascular physiology and pathophysiology by inducing adaptive as well as pathological changes in endothelial phenotype and gene expression. In particular, maladaptive effects of periodic, unidirectional flow induced shear stress can trigger a variety of effects on several vascular cell types, particularly endothelial cells. While by now endothelial cells from diverse anatomic origins have been cultured, in-depth analyses of their responses to fluid shear have been hampered by the relative complexity of shear models (e.g., parallel plate flow chamber, cone and plate flow model). While these all represent excellent approaches, such models are technically complicated and suffer from drawbacks including relatively lengthy and complex setup time, low surface areas, requirements for pumps and pressurization often requiring sealants and gaskets, creating challenges to both maintenance of sterility and an inability to run multiple experiments. However, if higher throughput models of flow and shear were available, greater progress on vascular endothelial shear responses, particularly periodic shear research at the molecular level, might be more rapidly advanced. Here, we describe the construction and use of shear rings: a novel, simple-to-assemble, and inexpensive tissue culture model with a relatively large surface area that easily allows for a high number of experimental replicates in unidirectional, periodic shear stress studies on endothelial cells.

The Assembly and Application of &#039;Shear Rings&#039;: A Novel Endothelial Model for Orbital, Unidirectional and Periodic Fluid Flow and Shear Stress

Different levels and patterns of fluid shear are known to modulate endothelial gene expression, phenotype and susceptibility to disease. We discuss the assembly and use of 'shear rings': a model that produces unidirectional, periodic shear stress patterns. Shear rings are simple to assemble, economical and can produce high cell yields.

Deviations from normal levels and patterns of vascular fluid shear play important roles in vascular physiology and pathophysiology by inducing adaptive as ...

Magnetic-Activated Cell Sorting Strategies to Isolate and Purify Synovial Fluid-Derived Mesenchymal Stem Cells from a Rabbit Model

Mesenchymal stem cells (MSCs) are the main cell source for cell-based therapy. MSCs from articular cavity synovial fluid could potentially be used for cartilage tissue engineering. MSCs from synovial fluid (SF-MSCs) have been considered promising candidates for articular regeneration, and their potential therapeutic benefit has made them an important research topic of late. SF-MSCs from the knee cavity of the New Zealand white rabbit can be employed as an optimized translational model to assess human regenerative medicine. By means of CD90-based magnetic activated cell sorting (MACS) technologies, this protocol successfully obtains rabbit SF-MSCs (rbSF-MSCs) from this rabbit model and further fully demonstrates the MSC phenotype of these cells by inducing them to differentiate to osteoblasts, adipocytes, and chondrocytes. Therefore, this approach can be applied in cell biology research and tissue engineering using simple equipment and procedures.

This article presents a simple and economic protocol for the straightforward isolation and purification of mesenchymal stem cells from New Zealand white rabbit synovial fluid.

Mesenchymal stem cells (MSCs) are the main cell source for cell-based therapy. MSCs from articular cavity synovial fluid could potentially be used for ...

3D Culturing of Organoids from the Intestinal Villi Epithelium Undergoing Dedifferentiation

Clonogenicity of organoids from the intestinal epithelium is attributed to the presence of stem cells therein. The mouse small intestinal epithelium is compartmentalized into crypts and villi: the stem and proliferating cells are confined to the crypts, whereas the villi epithelium contains only differentiated cells. Hence, the normal intestinal crypts, but not the villi, can give rise to organoids in 3D cultures. The procedure described here is applicable only to villus epithelium undergoing dedifferentiation leading to stemness. The method described uses the Smad4-loss-of-function:&#946;-catenin gain-of-function (Smad4KO:&#946;-cateninGOF) conditional mutant mouse. The mutation causes the intestinal villi to dedifferentiate and generate stem cells in the villi. Intestinal villi undergoing dedifferentiation are scraped off the intestine using glass slides, placed in a 70 &#181;m strainer and washed several times to filter out any loose cells or crypts prior to plating in BME-R1 matrix to determine their organoid-forming potential. Two main criteria were used to ensure that the resulting organoids were developed from the dedifferentiating villus compartment and not from the crypts: 1) microscopically evaluating&#160;the isolated villi to ensure absence of any tethered crypts, both before and after plating in the 3D matrix, and 2) monitoring the time course of organoid development from the villi. Organoid initiation from the villi occurs only two to five days after plating and appears irregularly shaped, whereas the crypt-derived organoids from the same intestinal epithelium are apparent within sixteen hours of plating and appear spherical. The limitation of the method, however, is that the number of organoids formed, and the time required for organoid initiation from the villi vary depending on the degree of dedifferentiation. Hence, depending upon the specificity of the mutation or the insult causing the dedifferentiation, the optimal stage at which villi can be harvested to assay their organoid forming potential, must be determined empirically.

The procedure describes isolation of the villi from the mouse intestinal epithelium undergoing dedifferentiation to determine their organoid forming potential.

Clonogenicity of organoids from the intestinal epithelium is attributed to the presence of stem cells therein. The mouse small intestinal epithelium is ...