The authors would like to acknowledge American Heart Association National Scientist Development Grant (10SDG2600001), Stanford Bio-X Interdisciplinary Initiative Program, and Stanford Medical Scholars Research Program for funding.

1. Polymer Synthesis
<ol>
	<li>In a fume hood, weigh out 3,523 mg of butanediol diacrylate (C) and transfer to a glass scintillation vial containing a stir bar.</li>
	<li>Pre-heat 5-amino-1-pentanol (32) to 90 &#176;C to solubilize the salt, then in a fume hood, weigh out 1,533 mg 32 and add to the scintillation vial containing C. This method will result in a molar ratio of C:32 = 1:1.2.</li>
	<li>Immediately place the vial containing both solutions onto a stir plate. Set stir speed at 600 rpm.</li>
	<li>Transfer the s...

<ol>
	<li>Deveza, L., Choi, J., Yang, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Therapeutic+angiogenesis+for+treating+cardiovascular+diseases.">Therapeutic angiogenesis for treating cardiovascular diseases.</a> Theranostics. 2, 801-814 (2012).</li><li>Yang, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetic+engineering+of+human+stem+cells+for+enhanced+angiogenesis+using+biodegradable+polymeric+nanoparticles.">Genetic engineering of human stem cells for enhanced angiogenesis using biodegradable polymeric nanoparticles.</a> Proc. Natl. Acad. Sci. U.S.A. 107, 3317-3322 (2010).</li><li>Mangi, A. 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=Mesenchymal+stem+cells+modified+with+Akt+prevent+remodeling+and+restore+performance+of+infarcted+hearts.">Mesenchymal stem cells modified with Akt prevent remodeling and restore performance of infarcted hearts.</a> Nat Med. 9, 1195-1201 (2003).</li><li>Lee, J. Y., 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=Enhancement+of+bone+healing+based+on+ex+vivo+gene+therapy+using+human+muscle-derived+cells+expressing+bone+morphogenetic+protein+2.">Enhancement of bone healing based on ex vivo gene therapy using human muscle-derived cells expressing bone morphogenetic protein 2.</a> Hum. Gene Ther. 13, 1201-1211 (2002).</li><li>Park, K. 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=Neural+stem+cells+may+be+uniquely+suited+for+combined+gene+therapy+and+cell+replacement:+Evidence+from+engraftment+of+Neurotrophin-3-expressing+stem+cells+in+hypoxic-ischemic+brain+injury.">Neural stem cells may be uniquely suited for combined gene therapy and cell replacement: Evidence from engraftment of Neurotrophin-3-expressing stem cells in hypoxic-ischemic brain injury.</a> Exp. Neurol. 199, 179-190 (2006).</li><li>Green, J. J., Langer, R., Anderson, D. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+combinatorial+polymer+library+approach+yields+insight+into+nonviral+gene+delivery.">A combinatorial polymer library approach yields insight into nonviral gene delivery.</a> Acc Chem Res. 41, 749-759 (2008).</li><li>Yang, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gene+delivery+to+human+adult+and+embryonic+cell-derived+stem+cells+using+biodegradable+nanoparticulate+polymeric+vectors.">Gene delivery to human adult and embryonic cell-derived stem cells using biodegradable nanoparticulate polymeric vectors.</a> Gene Ther. 16, 533-546 (2009).</li><li>Niiyama, H., Huang, N. F., Rollins, M. D., Cooke, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Murine+model+of+hindlimb+ischemia.">Murine model of hindlimb ischemia.</a> J. Vis. Exp. , e1035 (2009).</li><li>Ceradini, D. 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=Progenitor+cell+trafficking+is+regulated+by+hypoxic+gradients+through+HIF-1+induction+of+SDF-1.">Progenitor cell trafficking is regulated by hypoxic gradients through HIF-1 induction of SDF-1.</a> Nat. Med. 10, 858-864 (2004).</li><li>Kidd, 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=Direct+evidence+of+mesenchymal+stem+cell+tropism+for+tumor+and+wounding+microenvironments+using+in+vivo+bioluminescent+imaging.">Direct evidence of mesenchymal stem cell tropism for tumor and wounding microenvironments using in vivo bioluminescent imaging.</a> Stem Cells. 27, 2614-2623 (2009).</li><li>Sunshine, 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=Small-molecule+end-groups+of+linear+polymer+determine+cell-type+gene-delivery+efficacy.">Small-molecule end-groups of linear polymer determine cell-type gene-delivery efficacy.</a> Adv. Mater. 21, 4947-4951 (2009).</li><li>Sunshine, J. C., Akanda, M. I., Li, D., Kozielski, K. L., Green, J. 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+base+polymer+hydrophobicity+and+end-group+modification+on+polymeric+gene+delivery.">Effects of base polymer hydrophobicity and end-group modification on polymeric gene delivery.</a> Biomacromolecules. 12, 3592-3600 (2011).</li><li>Lynn, D. M., Langer, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Degradable+poly(&#946;-amino+esters):+Synthesis,+characterization,+and+self-assembly+with+plasmid+DNA.">Degradable poly(&#946;-amino esters): Synthesis, characterization, and self-assembly with plasmid DNA.</a> J. Am. Chem. Soc. 122, 10761-10768 (2000).</li><li>Eltoukhy, A. 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=Effect+of+molecular+weight+of+amine+end-modified+poly(beta-amino+ester)s+on+gene+delivery+efficiency+and+toxicity.">Effect of molecular weight of amine end-modified poly(beta-amino ester)s on gene delivery efficiency and toxicity.</a> Biomaterials. 33, 3594-3603 (2012).</li><li>Glover, D. J., Lipps, H. J., Jans, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Towards+safe,+non-viral+therapeutic+gene+expression+in+humans.">Towards safe, non-viral therapeutic gene expression in humans.</a> Nat. Rev. Genet. 6, 299-310 (2005).</li><li>Dave, U. P., Jenkins, N. A., Copeland, N. 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Here we report a method to program adult stem cells to overexpress therapeutic factors using non-viral, biodegradable nanoparticles. This platform is particularly useful for treating diseases where stem cells can naturally home, such as ischemia and cancer.9-10 Furthermore, the non-viral gene delivery platform allows for transient overexpression of therapeutic factors, which is suitable for most tissue regeneration and wound healing processes. The transfection process depends upon efficient DNA entry into cell...

The overall goal of this technique is to promote therapeutic angiogenesis using non-virally programmed stem cells overexpressing therapeutic factors at the site of ischemia. Stem cells were modified ex vivo first using biodegradable nanoparticles synthesized in the lab, and then transplanted in a murine model of hindlimb ischemia to validate their potential for enhancing angiogenesis and tissue salvage.

	Controlled vascular growth is an important component of successful tissue regeneration, as well as for treating various ischemic diseases such as stroke, limb ischemia, and myocardial infarction. Several strategies have been developed to promote vascular growth, including growth factor delivery and cell-based therapy.1 Despite the efficacy observed in the animal disease models, these methods still face limitations such as the need for supraphysiological doses for growth factor delivery, or insufficient paracrine release by cells alone. One potential strategy to overcome the above limitations is to combine stem cell therapy and gene therapy, whereby stem cells are genetically programmed ex vivo prior to transplantation to overexpress desirable therapeutic factors. This approach has been demonstrated in various disease models including hindlimb ischemia2, heart disease3, bone healing4 and neural injury5, etc. However, most gene therapy techniques rely on viral vectors, which are associated with safety concerns such as potential immunogenicity and insertional mutagenesis. Biomaterials mediated non-viral gene delivery may overcome these limitations, but often suffer from low transfection efficiency. To speed up the discovery of novel biomaterials for efficient non-viral gene delivery, recent studies have employed combinatorial chemistry and high-throughput screening approach. Biodegradable polymer libraries such as poly(&beta;-amino esters) (PBAE) have been developed and screened, which led to the discovery of leading polymers with markedly enhanced transfection efficiency compared to the conventional polymeric vector counterparts.6-7
Herein, we describe the synthesis of PBAE and verification of their ability to transfect adipose-derived stem cells (ADSCs) in vitro, followed by subsequent transplantation of genetically-modified ADSCs overexpressing vascular endothelial growth factor (VEGF) in a murine model of hindlimb ischemia. The outcomes were evaluated by tracking cell fate using bioluminescence imaging, assessing tissue reperfusion using laser Doppler perfusion imaging (LDPI), and determining angiogenesis and tissue salvage by histology.

<table border="1">
	<tbody>
		<tr>
			<td>
				Name of the Reagent</td>
			<td>
				Company</td>
			<td>
				Catalogue Number</td>
			<td>
				Comments (optional)</td>
		</tr>
		<tr>
			<td>
				DMEM</td>
			<td>
				Invitrogen</td>
			<td>
				11965</td>
			<td>
				&nbsp;</td>
		</tr>
		<tr>
			<td>
				Fetal Bovine Serum</td>
			<td>
				Invitrogen</td>
			<td>
				10082</td>
			<td>
				&nbsp;</td>
		</tr>
		<tr>
			<td>
				Penicillin/Streptomycin</td>
			<td>
				Invitrogen</td>
			<td>
				15070</td>
			<td>
				&nbsp;</td>
		</tr>
		<tr>
			<td>
				Basic Fibroblast Growth Factor</td>
			<td>
				Peprotech</td>
			<td>
				100-18B</td>
			<td>
				&nbsp;</td>
		</tr>
		<tr>
			<td>
				1,4-Butanediol Diacrylate (90%)</td>
			<td>
				Sigma Aldrich</td>
			<td>
				411744</td>
			<td>
				Acronym: C</td>
		</tr>
		<tr>
			<td>
				5-amino-1-pentanol (97%)</td>
			<td>
				Alfa Aesar</td>
			<td>
				2508-29-4</td>
			<td>
				Acronym: 32</td>
		</tr>
		<tr>
			<td>
				Tetraethyleneglycoldiamine &gt;99%)</td>
			<td>
				Molecular Biosciences</td>
			<td>
				17774</td>
			<td>
				Acronym: 122</td>
		</tr>
		<tr>
			<td>
				Sodium Acetate</td>
			<td>
				G-Biosciences</td>
			<td>
				R010</td>
			<td>
				&nbsp;</td>
		</tr>
		<tr>
			<td>
				Phosphate Buffered Saline</td>
			<td>
				Invitrogen</td>
			<td>
				14190-144</td>
			<td>
				&nbsp;</td>
		</tr>
		<tr>
			<td>
				Tetrahyofuran Anhydrous (&gt;99.9%)</td>
			<td>
				Sigma Aldrich</td>
			<td>
				401757</td>
			<td>
				&nbsp;</td>
		</tr>
		<tr>
			<td>
				Diethyl Ether Anhydrous (&gt;99%)</td>
			<td>
				Fisher Scientific</td>
			<td>
				E138-4</td>
			<td>
				&nbsp;</td>
		</tr>
		<tr>
			<td>
				DMSO Anhydrous (&gt;99.9%)</td>
			<td>
				Sigma Aldrich</td>
			<td>
				276855</td>
			<td>
				&nbsp;</td>
		</tr>
		<tr>
			<td>
				Gelatin</td>
			<td>
				Sigma Aldrich</td>
			<td>
				G9391</td>
			<td>
				&nbsp;</td>
		</tr>
		<tr>
			<td>
				Trypsin-EDTA</td>
			<td>
				Invitrogen</td>
			<td>
				25200</td>
			<td>
				&nbsp;</td>
		</tr>
		<tr>
			<td>
				D-luciferin</td>
			<td>
				GoldBio</td>
			<td>
				&nbsp;</td>
			<td>
				&nbsp;</td>
		</tr>
		<tr>
			<td>
				Optimal Cutting Temperature (O.C.T)</td>
			<td>
				Tissue-Tek</td>
			<td>
				4583</td>
			<td>
				&nbsp;</td>
		</tr>
		<tr>
			<td>
				Rat anti-Mouse CD31</td>
			<td>
				BD Pharmingen</td>
			<td>
				550274</td>
			<td>
				&nbsp;</td>
		</tr>
		<tr>
			<td>
				Alexa Fluor 594 anti-rat IgG</td>
			<td>
				Invitrogen</td>
			<td>
				A11007</td>
			<td>
				&nbsp;</td>
		</tr>
	</tbody>
</table>

	&nbsp;

programming stem cells for therapeutic angiogenesis using biodegradable polymeric nanoparticles

Controlled vascular growth is critical for successful tissue regeneration and wound healing, as well as for treating ischemic diseases such as stroke, heart attack or peripheral arterial diseases. Direct delivery of angiogenic growth factors has the potential to stimulate new blood vessel growth, but is often associated with limitations such as lack of targeting and short half-life in vivo. Gene therapy offers an alternative approach by delivering genes encoding angiogenic factors, but often requires using virus, and is limited by safety concerns. Here we describe a recently developed strategy for stimulating vascular growth by programming stem cells to overexpress angiogenic factors in situ using biodegradable polymeric nanoparticles. Specifically our strategy utilized stem cells as delivery vehicles by taking advantage of their ability to migrate toward ischemic tissues in vivo. Using the optimized polymeric vectors, adipose-derived stem cells were modified to overexpress an angiogenic gene encoding vascular endothelial growth factor (VEGF). We described the processes for polymer synthesis, nanoparticle formation, transfecting stem cells in vitro, as well as methods for validating the efficacy of VEGF-expressing stem cells for promoting angiogenesis in a murine hindlimb ischemia model.

Upon mixing together, the positively-charged polymer (C32-122) and negatively-charged DNA plasmid self-assembles into nanoparticles. Nanoparticle formation may be confirmed through electrophoresis analysis i.e. the complexation between C32-122 and plasmid DNA will prevent mobilization of the DNA during electrophoresis. The polymer serves as a transfection reagent to facilitate enhanced uptake of DNA into the target cells and the subsequent expression of encoding proteins (Figure 2). Cells can be...

Watch this Scientific Journal Video about Programming Stem Cells for Therapeutic Angiogenesis Using Biodegradable Polymeric Nanoparticles at JoVE.com

Programming Stem Cells for Therapeutic Angiogenesis Using Biodegradable Polymeric Nanoparticles

We describe the method of programming stem cells to overexpress therapeutic factors for angiogenesis using biodegradable polymeric nanoparticles. Processes described include polymer synthesis, transfecting adipose-derived stem cells in vitro, and validating the efficacy of programmed stem cells to promote angiogenesis in a murine hindlimb ischemia model.

Controlled vascular growth is critical for successful tissue regeneration and wound healing, as well as for treating ischemic diseases such as stroke, ...

programming-stem-cells-for-therapeutic-angiogenesis-using

Research

JoVE Journal

Bioengineering

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