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Modular injectable matrices based on alginate solution/microsphere mixtures that gel in situ and co-deliver immunomodulatory factors

Paper ID Volume ID Publish Year Pages File Format Full-Text
1500 85 2009 14 PDF Available
Title
Modular injectable matrices based on alginate solution/microsphere mixtures that gel in situ and co-deliver immunomodulatory factors
Abstract

Biocompatible polymer solutions that can crosslink in situ following injection to form stable hydrogels are of interest as depots for sustained delivery of therapeutic factors or cells, and as scaffolds for regenerative medicine. Here, injectable self-gelling alginate formulations obtained by mixing alginate microspheres (as calcium reservoirs) with soluble alginate solutions were characterized for potential use in immunotherapy. Rapid redistribution of calcium ions from microspheres into the surrounding alginate solution led to crosslinking and formation of stable hydrogels. The mechanical properties of the resulting gels correlated with the concentration of calcium-reservoir microspheres added to the solution. Soluble factors such as the cytokine interleukin-2 were readily incorporated into self-gelling alginate matrices by simply mixing them with the formulation prior to gelation. Using alginate microspheres as modular components, strategies for binding immunostimulatory CpG oligonucleotides onto the surface of microspheres were also demonstrated. When injected subcutaneously in the flanks of mice, self-gelling alginate formed soft macroporous gels supporting cellular infiltration and allowing ready access to microspheres carrying therapeutic factors embedded in the matrix. This in situ gelling formulation may thus be useful for stimulating immune cells at desired locales, such as solid tumors or infection sites, as well as for other soft tissue regeneration applications.

Keywords
Alginate; Injectable hydrogel; Controlled release; Immobilized factors; Cell infiltration
First Page Preview
Modular injectable matrices based on alginate solution/microsphere mixtures that gel in situ and co-deliver immunomodulatory factors
Publisher
Database: Elsevier - ScienceDirect
Journal: Acta Biomaterialia - Volume 5, Issue 4, May 2009, Pages 969–982
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering