Name: generation of alginate microspheres for biomedical applications
Uploaded: 2012-08-12T14:00:00
Description: Watch this Scientific Journal Video about Generation of Alginate Microspheres for Biomedical Applications at JoVE.com

This study was supported by the US Department of Veterans Affairs (Washington D.C.), grants 0852048, 0731201, and 0854430 from the National Science Foundation (Arlington, VA), , and grant RO1 DK080897 from the National Institutes of Health (Bethesda, MD). Mr. Khanna received support from a generous donation by Mr. Edward Ross and Dr. Monica Moya from the Bill &amp; Melinda Gates Foundation (Seattle, WA).

The protocol here describes a three-step procedure for generating multilayered alginate microbeads (Figure 1). First, alginate microbeads are formed (Figure 2A). This procedure is described in section 1 below. Cells or proteins can be added to the microbeads in this step in order to act as a delivery system. The next step involves the formation of a permselective layer on the microbeads and is described in section 2. The final step involves the formation of an additional alginate lay...

<ol>
	<li>Darrabie, M. D., Kendall, W. F., Opara, E. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characteristics+of+Poly-L-+Ornithine-coated+alginate+microcapsules.">Characteristics of Poly-L- Ornithine-coated alginate microcapsules.</a> Biomaterials. 26, 6846-6852 (2005).</li><li>Yamagiwa, K., Kozawa, T., Ohkawa, A. <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+alginate+composition+and+gelling+conditions+on+diffusional+and+mechanical+properties+of+calcium-alginate+gel+beads.">Effects of alginate composition and gelling conditions on diffusional and mechanical properties of calcium-alginate gel beads.</a> J. Chem. Eng. Jpn. 28, 462-467 (1995).</li><li>Amsden, B., Turner, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diffusion+characteristics+of+calcium+alginate+gels.">Diffusion characteristics of calcium alginate gels.</a> Biotechnol. Bioeng. 65, 605-610 (1999).</li><li>Uriel, S., Brey, E. M., Greisler, H. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sustained+low+levels+of+fibroblast+growth+factor-1+promote+persistent+microvascular+network+formation.">Sustained low levels of fibroblast growth factor-1 promote persistent microvascular network formation.</a> Am. J. Surg. 192, 604-609 (2006).</li><li>Moya, M. L., Lucas, S., Francis-Sedlak, M., Liu, X., Garfinkel, M. R., Huang, J. J., Cheng, M. H., Opara, E. C., Brey, E. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sustained+delivery+of+FGF-1+increases+vascular+density+in+comparison+to+bolus+administration.">Sustained delivery of FGF-1 increases vascular density in comparison to bolus administration.</a> Microvasc. Res. 78, 142-147 (2009).</li><li>Moya, M. L., Cheng, M. H., Huang, J. J., Francis-Sedlak, M. E., Kao, S. W., Opara, E. C., Brey, E. 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+effect+of+FGF-1+loaded+alginate+microbeads+on+neovascularization+and+adipogenesis+in+a+vascular+pedicle+model+of+adipose+tissue+engineering.">The effect of FGF-1 loaded alginate microbeads on neovascularization and adipogenesis in a vascular pedicle model of adipose tissue engineering.</a> Biomaterials. 31, 2816-2826 (2010).</li><li>Khanna, O., Moya, M. L., Greisler, H. P., Opara, E. C., Brey, E. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multilayered+Microcapsules+for+the+Sustained-Release+of+Angiogenic+Proteins+From+Encapsulated+Cells.">Multilayered Microcapsules for the Sustained-Release of Angiogenic Proteins From Encapsulated Cells.</a> Am. J. Surg. 200, 655-658 (2010).</li><li>Khanna, O., Moya, M. L., Opara, E. C., Brey, E. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+of+multilayered+alginate+microcapsules+for+the+sustained-release+of+fibroblast+growth+factor-1.">Synthesis of multilayered alginate microcapsules for the sustained-release of fibroblast growth factor-1.</a> J. Biomed. Mater. Res. A. 95, 632-640 (2010).</li></ol>

Alginate is a natural, acidic polysaccharide extracted from algae and is composed of units of 1,4'-&beta;-D-mannuronic acid (M) and &#x03B1;-L-guluronic acid (G) 2,3. Simple gelation occurs when divalent cations, such as Ca2+, Sr2+, or Ba2+ interact with G-monomers forming ionic bridges between adjacent alginate chains. Microbeads of alginate have been utilized to deliver a variety of proteins, including fibroblast growth factor-1 (FGF-1), nerve growth factor, leukemia inhibiti...

<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>Pronova Ultrapure LVG alginate</td>
 <td>Nova-Matrix</td>
 <td>4200006</td>
 <td>A variety of alginate 			formulations are available. The choice of alginate influences the 			end properties of the microbeads, including size, mechanical 			properties, and transport. The composition used should be 			optimized for a given application. </td>
 </tr>
 <tr>
 <td>Pronova Ultrapure LVM alginate</td>
 <td>Nova-Matrix</td>
 <td>4200206</td>
 <td>A variety of alginate 			formulations are available. The choice of alginate influences the 			end properties of the microbeads, including size, mechanical 			properties, and transport. The composition used should be 			optimized for a given application. </td>
 </tr>
 <tr>
 <td>Poly-L-ornithine hydrochloride</td>
 <td>Sigma-Aldrich</td>
 <td>P2533</td>
 <td></td>
 </tr>
 </tbody>
</table>

generation of alginate microspheres for biomedical applications

Alginate-based materials have received considerable attention for biomedical applications because of their hydrophilic nature, biocompatibility, and physical architecture. Applications include cell encapsulation, drug delivery, stem cell culture, and tissue engineering scaffolds. In fact, clinical trials are currently being performed in which islets are encapsulated in PLO coated alginate microbeads as a treatment of type I diabetes. However, large numbers of islets are required for efficacy due to poor survival following transplantation. The ability to locally stimulate microvascular network formation around the encapsulated cells may increase their viability through improved transport of oxygen, glucose and other vital nutrients. Fibroblast growth factor-1 (FGF-1) is a naturally occurring growth factor that is able to stimulate blood vessel formation and improve oxygen levels in ischemic tissues. The efficacy of FGF-1 is enhanced when it is delivered in a sustained fashion rather than a single large-bolus administration. The local long-term release of growth factors from islet encapsulation systems could stimulate the growth of blood vessels directly towards the transplanted cells, potentially improving functional graft outcomes. In this article, we outline procedures for the preparation of alginate microspheres for use in biomedical applications. In addition, we describe a method we developed for generating multilayered alginate microbeads. Cells can be encapsulated in the inner alginate core, and angiogenic proteins in the outer alginate layer. The release of proteins from this outer layer would stimulate the formation of local microvascular networks directly towards the transplanted islets.

Watch this Scientific Journal Video about Generation of Alginate Microspheres for Biomedical Applications at JoVE.com

Generation of Alginate Microspheres for Biomedical Applications

In the following sections, we outline procedures for the preparation of alginate microspheres for use in biomedical applications. We specifically illustrate a technique for creating multilayered alginate microspheres for the dual purpose of cell and protein encapsulation as a potential treatment for type 1 diabetes.

Alginate-based materials have received considerable attention for biomedical applications because of their hydrophilic nature, biocompatibility, and ...

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