The current study was supported by Shanghai Innovation Funding (1402H294300) sponsored by the Science and Technology Commission of Shanghai Municipality (CN) to Dr. Wen Wang. We would like to thank Dr. Guangdong Zhou (National Tissue Engineering Center of China) for his technical assistance and scientific advice for this manuscript. We would also like to thank Mr. Huitang Xia (Shanghai Ninth People&#8217;s Hospital) for his help in animal welfare.

Procedures involving animal subjects were approved by the local Institutional Animal Care and Ethics Committee, with an effort to minimize animal suffering. The following protocol was approved by the Institutional Animal Care and Use Committee (IACUC) at Shanghai Ninth People&#8217;s Hospital affiliated to Shanghai JiaoTong University School of Medicine with the protocol number [2017]063.
1. Establishment of a Surgically-Induced Rat Knee Osteoarthritis Model
<ol>
	<li>For this surgical proce...

<ol>
	<li>Loeser, R. F., Goldring, S. R., Scanzello, C. R., Goldring, M. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Osteoarthritis:+a+disease+of+the+joint+as+an+organ.">Osteoarthritis: a disease of the joint as an organ.</a> Arthritis Rheum. 64 (6), 1697-1707 (2012).</li><li>Lane, N. E., Shidara, K., Wise, B. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Osteoarthritis+year+in+review+2016:+clinical.">Osteoarthritis year in review 2016: clinical.</a> Osteoarthritis Cartilage. 25 (2), 209-215 (2017).</li><li>Wang, W., Cao, W. <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+osteoarthritis+with+mesenchymal+stem+cells.">Treatment of osteoarthritis with mesenchymal stem cells.</a> Sci China Life Sci. 57 (6), 586-595 (2014).</li><li>Burke, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Therapeutic+potential+of+mesenchymal+stem+cell+based+therapy+for+osteoarthritis.">Therapeutic potential of mesenchymal stem cell based therapy for osteoarthritis.</a> Clin Transl Med. 5 (1), 27 (2016).</li><li>Bendele, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+of+osteoarthritis.">Animal models of osteoarthritis.</a> J Musculoskelet Neuronal Interact. 1 (4), 363-376 (2001).</li><li>Gerwin, N., Bendele, A. M., Glasson, S., Carlson, C. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+OARSI+histopathology+initiative+-+recommendations+for+histological+assessments+of+osteoarthritis+in+the+rat.">The OARSI histopathology initiative - recommendations for histological assessments of osteoarthritis in the rat.</a> Osteoarthritis Cartilage. 18, S24-S34 (2010).</li><li>Janusz, M. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Induction+of+osteoarthritis+in+the+rat+by+surgical+tear+of+the+meniscus:+Inhibition+of+joint+damage+by+a+matrix+metalloproteinase+inhibitor.">Induction of osteoarthritis in the rat by surgical tear of the meniscus: Inhibition of joint damage by a matrix metalloproteinase inhibitor.</a> Osteoarthritis Cartilage. 10 (10), 785-791 (2002).</li><li>Li, 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=In+vivo+human+adipose-derived+mesenchymal+stem+cell+tracking+after+intra-articular+delivery+in+a+rat+osteoarthritis+model.">In vivo human adipose-derived mesenchymal stem cell tracking after intra-articular delivery in a rat osteoarthritis model.</a> Stem Cell Res Ther. 7 (1), 160 (2016).</li><li>Zhou, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Administering+human+adipose-derived+mesenchymal+stem+cells+to+prevent+and+treat+experimental+arthritis.">Administering human adipose-derived mesenchymal stem cells to prevent and treat experimental arthritis.</a> Clin Immunol. 141 (3), 328-337 (2011).</li><li>Desando, G., 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=Intra-articular+delivery+of+adipose+derived+stromal+cells+attenuates+osteoarthritis+progression+in+an+experimental+rabbit+model.">Intra-articular delivery of adipose derived stromal cells attenuates osteoarthritis progression in an experimental rabbit model.</a> Arthritis Res Ther. 15 (1), 22 (2013).</li><li>Riester, S. 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=Safety+Studies+for+Use+of+Adipose+Tissue-Derived+Mesenchymal+Stromal/Stem+Cells+in+a+Rabbit+Model+for+Osteoarthritis+to+Support+a+Phase+I+Clinical+Trial.">Safety Studies for Use of Adipose Tissue-Derived Mesenchymal Stromal/Stem Cells in a Rabbit Model for Osteoarthritis to Support a Phase I Clinical Trial.</a> Stem Cells Transl Med. 6 (3), 910-922 (2017).</li><li>Bai, 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=Tracking+long-term+survival+of+intramyocardially+delivered+human+adipose+tissue-derived+stem+cells+using+bioluminescence+imaging.">Tracking long-term survival of intramyocardially delivered human adipose tissue-derived stem cells using bioluminescence imaging.</a> Mol Imaging Biol. 13 (4), 633-645 (2011).</li><li>Wolbank, 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=Labelling+of+human+adipose-derived+stem+cells+for+non-invasive+in+vivo+cell+tracking.">Labelling of human adipose-derived stem cells for non-invasive in vivo cell tracking.</a> Cell Tissue Bank. 8 (3), 163-177 (2007).</li><li>Heymer, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Iron+oxide+labelling+of+human+mesenchymal+stem+cells+in+collagen+hydrogels+for+articular+cartilage+repair.">Iron oxide labelling of human mesenchymal stem cells in collagen hydrogels for articular cartilage repair.</a> Biomaterials. 29 (10), 1473-1483 (2008).</li><li>Hemmrich, K., Meersch, M., von Heimburg, D., Pallua, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Applicability+of+the+dyes+CFSE,+CM-DiI+and+PKH26+for+tracking+of+human+preadipocytes+to+evaluate+adipose+tissue+engineering.">Applicability of the dyes CFSE, CM-DiI and PKH26 for tracking of human preadipocytes to evaluate adipose tissue engineering.</a> Cells Tissues Organs. 184 (3-4), 117-127 (2006).</li><li>Shim, G., 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=Pharmacokinetics+and+in+vivo+fate+of+intra-articularly+transplanted+human+bone+marrow-derived+clonal+mesenchymal+stem+cells.">Pharmacokinetics and in vivo fate of intra-articularly transplanted human bone marrow-derived clonal mesenchymal stem cells.</a> Stem Cells Dev. 24 (9), 1124-1132 (2015).</li><li>Chen, B. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+safety+study+on+intrathecal+delivery+of+autologous+mesenchymal+stromal+cells+in+rabbits+directly+supporting+Phase+I+human+trials.">A safety study on intrathecal delivery of autologous mesenchymal stromal cells in rabbits directly supporting Phase I human trials.</a> Transfusion. 55 (5), 1013-1020 (2015).</li><li>Chan, M. M., Gray, B. D., Pak, K. Y., Fong, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Non-invasive+in+vivo+imaging+of+arthritis+in+a+collagen-induced+murine+model+with+phosphatidylserine-binding+near-infrared+(NIR)+dye.">Non-invasive in vivo imaging of arthritis in a collagen-induced murine model with phosphatidylserine-binding near-infrared (NIR) dye.</a> Arthritis Res Ther. 17, 50 (2015).</li><li>Texier, I., 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=Cyanine-loaded+lipid+nanoparticles+for+improved+in+vivo+fluorescence+imaging.">Cyanine-loaded lipid nanoparticles for improved in vivo fluorescence imaging.</a> J Biomed Opt. 14 (5), 054005 (2009).</li><li>Honig, M. G., Hume, R. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluorescent+carbocyanine+dyes+allow+living+neurons+of+identified+origin+to+be+studied+in+long-term+cultures.">Fluorescent carbocyanine dyes allow living neurons of identified origin to be studied in long-term cultures.</a> J Cell Biol. 103 (1), 171-187 (1986).</li><li>Rahmati, M., Mobasheri, A., Mozafari, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inflammatory+mediators+in+osteoarthritis:+A+critical+review+of+the+state-of-the-art,+current+prospects,+and+future+challenges.">Inflammatory mediators in osteoarthritis: A critical review of the state-of-the-art, current prospects, and future challenges.</a> Bone. 85, 81-90 (2016).</li><li>Detante, O., 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=Intravenous+administration+of+99mTc-HMPAO-labeled+human+mesenchymal+stem+cells+after+stroke:+in+vivo+imaging+and+biodistribution.">Intravenous administration of 99mTc-HMPAO-labeled human mesenchymal stem cells after stroke: in vivo imaging and biodistribution.</a> Cell Transplant. 18 (12), 1369-1379 (2009).</li><li>Hu, S. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+magnetic+resonance+imaging+tracking+of+SPIO-labeled+human+umbilical+cord+mesenchymal+stem+cells.">In vivo magnetic resonance imaging tracking of SPIO-labeled human umbilical cord mesenchymal stem cells.</a> J Cell Biochem. 113 (3), 1005-1012 (2012).</li><li>Xia, Q., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intra-articular+transplantation+of+atsttrin-transduced+mesenchymal+stem+cells+ameliorate+osteoarthritis+development.">Intra-articular transplantation of atsttrin-transduced mesenchymal stem cells ameliorate osteoarthritis development.</a> Stem Cells Transl Med. 4 (5), 523-531 (2015).</li><li>Jasmin, , 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=Optimized+labeling+of+bone+marrow+mesenchymal+cells+with+superparamagnetic+iron+oxide+nanoparticles+and+in+vivo+visualization+by+magnetic+resonance+imaging.">Optimized labeling of bone marrow mesenchymal cells with superparamagnetic iron oxide nanoparticles and in vivo visualization by magnetic resonance imaging.</a> J Nanobiotechnology. 9, 4 (2011).</li><li>Lehmann, T. 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=Coculture+of+human+nucleus+pulposus+cells+with+multipotent+mesenchymal+stromal+cells+from+human+bone+marrow+reveals+formation+of+tunnelling+nanotubes.">Coculture of human nucleus pulposus cells with multipotent mesenchymal stromal cells from human bone marrow reveals formation of tunnelling nanotubes.</a> Mol Med Rep. 9 (2), 574-582 (2014).</li><li>Wang, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+adipose-derived+mesenchymal+progenitor+cells+engraft+into+rabbit+articular+cartilage.">Human adipose-derived mesenchymal progenitor cells engraft into rabbit articular cartilage.</a> Int J Mol Sci. 16 (6), 12076-12091 (2015).</li></ol>

Meng Li, Ming Hao and Wen Wang are current employees and stock option holders of Cellular Biomedicine Group (Nasdaq: CBMG). The other authors declare no conflict of interest.

Safety standards and biodistribution studies of stem cell therapy are urgently needed before we can bring regenerative stem cell treatment for KOA from the bench to the bedside. However, the pathological environment of disease plays an important role in the persistence and biodistribution of transplanted haMSCs10. Recently, our group demonstrated that intra-articular injection of haMSCs persisted longer in a pathological KOA environment than did injections under normal conditions...

Knee osteoarthritis (KOA) is a degenerative disorder resulting from articular cartilage loss and progressive inflammation, which has become a major chronic disease in the elderly around the world1. However, current therapies using anti-inflammatory drugs, physical supplements, and surgical procedures may only provide temporary relief for symptomatic pain2.
Human adipose-derived mesenchymal stem cells (haMSCs) have become a promising regenerative remedy for knee osteoarthritis, owing to their multipotent differentiation potential for cartilage regeneration and immunomodulatory properties3,4. Compared with pharmacological routes to investigate mechanisms of action in vivo, tracking live haMSCs in small KOA animal models is currently instructive to establish the rationale for and feasibility of haMSC therapy prior to clinical application. For preclinical testing, medial meniscectomy (MM) destabilizes the mechanical load of the joint to induce KOA in rats, which provides a relatively feasible model with consistent reproducibility5. The onset of KOA induced by MM is earlier than anterior cruciate ligament transection alone or combined with partial medial meniscectomy6. Therefore, the long-term interactions between injected haMSCs with the pathological microenvironment of KOA are often assessed in rats induced by MM7,8.
Though the therapeutic efficacy of haMSCs has been extensively reported, relevant knowledge on the in vivo persistence of implanted haMSCs via intra-articular (IA) injection is scarce9,10. Hence, various cellular labeling methods have been developed, including immunohistology11, luciferase12, green fluorescent protein13 transfection, iron oxide labeling for magnetic resonance imaging (MRI)14, and numerous fluorescent cell dyes8,15,16. Compared with labor-intensive histology analyses, in vivo non-invasive imaging employs optical devices to detect the real-time distribution and dynamics of cells labeled with fluorescent signals10,17. For functional live cell imaging, cytocompatible fluorescent labeling is a sophisticated radioactive-free tracking technique to reveal cellular activities after stem cell transplantation18. Moreover, multicolor fluorescent lipophilic dyes possess advantages over amino-reactive hydrophilic dyes or fluorescent proteins, including their improved cell permeability and enhanced fluorescence quantum yields19.
Thus, the protocols included here utilize a red laser to excite cells labeled with lipophilic carbocyanines DiD (DilC18(5)), which is a far-red fluorescent Dil (dialkylcarbocyanines) analog20. The red-shifted excitation and emission spectra of DiD avoids autofluorescent interference and allows deep-tissue imaging over a long period of time in live animals8. This method of tracking cells in vivo labeled with DiD is valid for monitoring transplanted stem cells, such as haMSCs, in animal models, which is essential to understand and improve current stem cell regenerative therapy.

<table>
	<tbody>
		<tr>
			<td>Matrx VMR animal anesthesia system</td>
			<td>Midmark</td>
			<td>VIP3000</td>
			<td></td>
		</tr>
		<tr>
			<td>4-0 suture</td>
			<td>Shanghai Jinhuan</td>
			<td>KC439</td>
			<td></td>
		</tr>
		<tr>
			<td>Razor</td>
			<td>Pritech</td>
			<td>LD-9987</td>
			<td></td>
		</tr>
		<tr>
			<td>Gentamicin</td>
			<td>Zhejiang Jindakang Animal Health Product Co., Ltd.</td>
			<td>None</td>
			<td></td>
		</tr>
		<tr>
			<td>0.9% Sodium chloride solution</td>
			<td>Hunan Kelun Pharmaceutical Co., Ltd.</td>
			<td>H43020455</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin</td>
			<td>Shanghai Kangfu chemical pharmaceutical Co., Ltd.</td>
			<td>None</td>
			<td></td>
		</tr>
		<tr>
			<td>Buprenorphine</td>
			<td>Tianjin Pharmaceutical Research Institute Pharmaceutical Co., Ltd.</td>
			<td>None</td>
			<td></td>
		</tr>
		<tr>
			<td>Paraformaldehyde</td>
			<td>Sigma-Aldrich</td>
			<td>16005</td>
			<td>Dilute to final concentration of 10% in PBS</td>
		</tr>
		<tr>
			<td>EDTA</td>
			<td>Sigma-Aldrich</td>
			<td>E9884</td>
			<td>Dilute to final concentration of 20% in PBS</td>
		</tr>
		<tr>
			<td>0.1% Hematoxylin Solution, Mayer&#8217;s</td>
			<td>Sigma-Aldrich</td>
			<td>MHS16</td>
			<td></td>
		</tr>
		<tr>
			<td>0.5% Eosin Y solution, alcoholic</td>
			<td>Sigma-Aldrich</td>
			<td>HT110116</td>
			<td></td>
		</tr>
		<tr>
			<td>Safranin O</td>
			<td>Sigma-Aldrich</td>
			<td>S8884</td>
			<td></td>
		</tr>
		<tr>
			<td>Fast Green</td>
			<td>Sigma-Aldrich</td>
			<td>F7258</td>
			<td></td>
		</tr>
		<tr>
			<td>Shandon Excelsior ESTM Tissue Processor</td>
			<td>Thermo Fisher</td>
			<td>A78400006</td>
			<td></td>
		</tr>
		<tr>
			<td>Shandon Histocentre&#8482; 3 Tissue Embedding Center</td>
			<td>Thermo Fisher</td>
			<td>B64100010</td>
			<td></td>
		</tr>
		<tr>
			<td>Fully Automated Rotary Microtome</td>
			<td>Leica</td>
			<td>RM2255</td>
			<td></td>
		</tr>
		<tr>
			<td>DiD</td>
			<td>Molecular Probes, Life 
			Technologies</td>
			<td>V-22887</td>
			<td></td>
		</tr>
		<tr>
			<td>D-MEM High Glucose</td>
			<td>Sigma-Aldrich</td>
			<td>D5648</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS</td>
			<td>GIBCO, Life Technologies</td>
			<td>14190-144</td>
			<td></td>
		</tr>
		<tr>
			<td>0.25% Trypsin-EDTA</td>
			<td>Invitrogen</td>
			<td>25200-114</td>
			<td></td>
		</tr>
		<tr>
			<td>10 cm Petri Dish</td>
			<td>Corning</td>
			<td>V118877</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>Beckman</td>
			<td>Optima MAX-TL</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescent microscope</td>
			<td>Olympus</td>
			<td>BX53</td>
			<td></td>
		</tr>
		<tr>
			<td>0.4% Trypan Blue solution</td>
			<td>Sigma-Aldrich</td>
			<td>93595</td>
			<td></td>
		</tr>
		<tr>
			<td>Titetamme</td>
			<td>Virbac (Zoletil 50)</td>
			<td>1000000188</td>
			<td></td>
		</tr>
		<tr>
			<td>Zolazepam</td>
			<td>Virbac (Zoletil 50)</td>
			<td>1000000188</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile hyposermic syringe for single use 26G</td>
			<td>Shanghai Misawa Medical Industry</td>
			<td>None</td>
			<td></td>
		</tr>
		<tr>
			<td>IVIS Spectrum In Vivo Imaging System</td>
			<td>PerkinElmer</td>
			<td>124262</td>
			<td></td>
		</tr>
		<tr>
			<td>Living Imaging 4.0 software</td>
			<td>PerkinElmer</td>
			<td>None</td>
			<td></td>
		</tr>
	</tbody>
</table>

in vivo tracking of human adipose-derived mesenchymal stem cells in a rat knee osteoarthritis model with fluorescent lipophilic membrane dye

In order to support the clinical application of human adipose-derived mesenchymal stem cell (haMSC) therapy for knee osteoarthritis (KOA), we examined the efficacy of cell persistence and biodistribution of haMSCs in animal models. We demonstrated a method to label the cell membrane of haMSCs with lipophilic fluorescent dye. Subsequently, intra-articular injection of the labeled cells in rats with surgically induced KOA was monitored dynamically by an in vivo imaging system. We employed the lipophilic carbocyanines DiD (DilC18 (5)), a far-red fluorescent Dil (dialkylcarbocyanines) analog, which utilized a red laser to avoid excitation of the natural green autofluorescence from surrounding tissues. Furthermore, the red-shifted emission spectra of DiD allowed deep-tissue imaging in live animals and the labeling procedure caused no cytotoxic effects or functional damage to haMSCs. This approach has been shown to be an efficient tracking method for haMSCs in a rat KOA model. The application of this method could also be used to determine the optimal administration route and dosage of MSCs from other sources in pre-clinical studies.

In order to induce KOA model, MM was performed in the right knee joint of SD rats (Figure 3). Eight weeks after surgery, rats were sacrificed and the serial sections of knee joints were evaluated with both H&#38;E and Safranin O/Fast Green staining (Figure 4). For H&#38;E staining, the surface of the articular cartilage exhibited rougher borders in the surgery knees than the normal joint without surgery. For Safranin-O/Fast green...

Watch this Scientific Journal Video about In Vivo Tracking of Human Adipose-derived Mesenchymal Stem Cells in a Rat Knee Osteoarthritis Model with Fluorescent Lipophilic Membrane Dye at JoVE.com

In Vivo Tracking of Human Adipose-derived Mesenchymal Stem Cells in a Rat Knee Osteoarthritis Model with Fluorescent Lipophilic Membrane Dye

This protocol describes an efficient way to monitor the cell persistence and biodistribution of human adipose-derived mesenchymal stem cells (haMSCs) by far-red fluorescence labeling in a rat knee osteoarthritis (KOA) model via intra-articular (IA) injection.

In Vivo Tracking of Human Adipose-derived Mesenchymal Stem Cells in a Rat Knee Osteoarthritis Model with Fluorescent Lipophilic Membrane Dye

In order to support the clinical application of human adipose-derived mesenchymal stem cell (haMSC) therapy for knee osteoarthritis (KOA), we examined the ...

The overall goal of this procedure is to evaluate the efficacy of the cell persistence and biodistribution of human adipose-derived mesenchymal stem cells in a rat knee ostearthritis, or a KOA model, using in vivo fluorescent imaging. In vivo stem cell tracking can help answer key question in the regenerative math-ing field about irritation and distribution of human adipose derived in mesenchymal stem cells in KOA animal models. The main advantage of using DiD is that its rat-shifted emission spectrum allows deep tissue imaging in live animals with no cytotic effects or functional damage to the dye-labeled cells.Begin by placing an anesthetized 250 to 300 gram, eight to 12 week old male Sprague Dawley rat in the left lateral position on a heated pad. Use a razor to thoroughly shave the right knee, and disinfect the surgical area with 10%povidone iodine solution and 70%ethanol. Cover the nonsurgical area with a surgical pad.And use a scalpel to make a two centimeter incision laterally along the patellar tendon to expose the joint capsules. Next, use a surgical scalpel to transect the medial collateral ligament, reflecting the meniscus toward the femur, and grasp the medial meniscus with forceps. Use a scalpel to cut through the meniscus at its narrowest point from the tibial attachment.To obtain a reliable and feasible KOA onset, the femur side of the meniscus should be completely cut through in each experimental animal. Then, close the joint capsule with a four-O observable suture and monitor the rat until it is fully recovered. Eight weeks after surgery, detach human adipose-derived mesenchymal cells from an 80%confluent culture with two milliliters of trypsin plus EDTA for three minutes at 37 degrees celsius.After a few minutes, neutralize the trypsin with four milliliters of complete culture medium and collect the cells by centrifugation. Resuspend the pellet at a one times 10 to the sixth cells per milliliter concentration in five milliliters of serum-free culture medium. And label the cells with 50 microliters of DiD cell labeling solution for 50 minutes at 37 degrees celsius.At the end of the incubation, collect the cells by centrifugation and wash them two times in five milliliters of PBS per wash. After the last centrifugation, dilute the cells to a 2.5 times 10 to the sixth viable cells per 100 microliters of PBS concentration and load the cells into a one milliliter syringe equipped with a 26 gauge needle. Next, reshave the arthritic knee of the first experimental animal to expose the joint area, and disinfect the exposed skin with 70%ethanol.Inject the labeled cells into the center of the triangle formed by the medial side of the patellar ligament, the medial femoral condyle, and the medial tibial condyle, and open the imaging software. Initialize the in vivo bioluminescence imaging system and position the animals in the supine position within the central stage of the imaging system. With the chamber door closed, check the fluorescent box and select the appropriate excitation and emission fluorescent filter sets.Set the field of view to D, the pixel bending to eight, the F Stop to two, and the exposure time to auto. After obtaining the images, allow the animals to recover on a heat pad with monitoring until full recovery. Then, in the appropriate image analysis software, select the units of radiant efficiency for the measurement of the fluorescence and the regions of interest for analysis and quantify the fluorescent signals from each image.In this representative experiment, serial sections of the knee joint of a knee osteoarthritis induced rat were evaluated by H&E and safranin O/Fast Green staining eight weeks after the surgery. The thickness of the articular cartilage is thinner in the arthritic knees than in the contralateral joints without surgery as observed in the H&E stained sections. Further, the proteoglycan is decreased and the fibrillated collagen is increased in the arthritis joint as visualized by safranin O/Fast Green staining, indicating the progression of the degenerative knee osteoarthritis phenotype induced by the surgery.One hour after staining, DiD labeled human adipose-derived mesenchymal cells exhibit a round shape in vitro. After 24 hours, cultured DiD labeled mesenchymal cells demonstrate a long spindle shape confirming that DiD does not change the adherence ability of the cells. Imaging the knees of the osteoarthritic animals eight weeks after surgery reveals the presence of the DiD labeled cells from day zero until day 70 post injection.After its development, this technique paved the way for researchers in the stem cell therapy field to determine the optimal routine and dosage for the safe and feasible injection of mesenchymal stem cells for the treatment of knee osteoarthritis in animals. After watching this video, you should have a good understanding of how to label human mesenchymal stem cell with DiD for the injection and in vivo tracking in the surgically induced rat KOA model.

in-vivo-tracking-human-adipose-derived-mesenchymal-stem-cells-rat

Research

JoVE Journal

Developmental Biology

8.9K Görüntüleme.  Cellular Biomedicine Group, China. The overall goal of this procedure is to evaluate the efficacy of the cell persistence and biodistribution of human adipose-derived mesenchymal stem cells in a rat knee ostearthritis, or a KOA model, using in vivo fluorescent imaging. In vivo stem cell tracking can help answer key question in the regenerative math-ing field about irritation and distribution of human adipose derived in mesenchymal stem cells in KOA animal models. The main advantage of using DiD is that its rat-shifted emission...