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Cell-mediated delivery of glucocorticoids from thiol-ene hydrogels.

ABSTRACT: Thiol-ene-based poly(ethylene glycol) (PEG) hydrogels provide a unique functional platform for the sustained and localized delivery of bioactive small molecules like glucocorticoids. As a proof of concept, the synthetic glucocorticoid Dexamethasone (Dex) was conjugated to the N-terminus of a matrix metalloproteinase(MMP)-degradable peptide, which was then easily co-polymerized into PEG gel scaffolds by a thiol-ene polymerization mechanism. The conjugated Dex was locally sequestered until released by cleavage of the MMP-degradable peptide tether triggered by cell-secreted MMPs, and was only available for uptake by local co-encapsulated cells. Elevated alkaline phosphatase (ALP) activities and calcium deposition levels were observed for human mesenchymal stem cells (hMSCs) that were encapsulated in PEG hydrogels functionalized with 10 ?M of a Dexamethasone-conjugated peptide (Dex-peptide). The cellular responses stimulated by the tethered Dex lasted for over 21 days. Using co-culture experiments, hMSCs encapsulated in hydrogels with the MMP-degradable Dex-peptides had elevated levels of ALP activity and calcium deposition, whereas no elevated cellular responses were observed in co-cultured hMSCs surrounding the gel. Moreover, modifying the peptide sequence to alter its susceptibility to cleavage and/or changing the Dex-peptide loading further regulated the hMSC response to Dex at different levels and on different time scales. Collectively, these results demonstrate a tunable system for the delivery of glucocorticoids in a localized and cell-dictated manner.

SUBMITTER: Yang C

PROVIDER: S-EPMC3487401 | biostudies-literature | 2012 Sep

REPOSITORIES: biostudies-literature

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Cell-mediated delivery of glucocorticoids from thiol-ene hydrogels.

Yang Chun C Mariner Peter D PD Nahreini Jhenya N JN Anseth Kristi S KS

Journal of controlled release : official journal of the Controlled Release Society 20120811 3

Thiol-ene-based poly(ethylene glycol) (PEG) hydrogels provide a unique functional platform for the sustained and localized delivery of bioactive small molecules like glucocorticoids. As a proof of concept, the synthetic glucocorticoid Dexamethasone (Dex) was conjugated to the N-terminus of a matrix metalloproteinase(MMP)-degradable peptide, which was then easily co-polymerized into PEG gel scaffolds by a thiol-ene polymerization mechanism. The conjugated Dex was locally sequestered until release ...[more]

PMID: 22902591

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Project description:Hydrogels with dynamically tunable crosslinking are invaluable for directing stem cell fate and mimicking a stiffening matrix during fibrosis or tumor development. The increases in matrix stiffness during tissue development are often accompanied by the accumulation of extracellular matrices (e.g., collagen, hyaluronic acid (HA)), a phenomenon that has received little attention in the development of dynamic hydrogels. In this contribution, we present a gelatin-based cell-laden hydrogel system capable of being dynamically stiffened while accumulating HA, a key glycosaminoglycans (GAG) increasingly deposited by stromal cells during tumor progression. Central to this strategy is the synthesis of a dually-modified gelatin macromer - gelatin-norbornene-carbohydrazide (GelNB-CH), which is susceptible to both thiol-norbornene photopolymerization and hydrazone click chemistry. We demonstrate that the crosslinking density of cell-laden thiol-norbornene hydrogels can be dynamically tuned via simple incubation with aldehyde-bearing macromers (e.g., oxidized dextran (oDex) or oHA). The GelNB-CH hydrogel system is highly cytocompatible, as demonstrated by in situ encapsulation of pancreatic cancer cells (PCC) and cancer-associated fibroblasts (CAF). This unique dynamic stiffening scheme provides a platform to study tandem accumulation of HA and elevation in matrix stiffness in the pancreatic tumor microenvironment. STATEMENT OF SIGNIFICANCE: Hydrogels permitting on-demand and secondary crosslinking are ideal for mimicking a stiffening tumor microenvironment (TME). However, none of the current dynamic hydrogels account for both stiffening and accumulation of hyaluronic acid (HA), a major extracellular matrix component increasingly deposited in tumor stromal tissues, including pancreatic ductal adenocarcinoma (PDAC). The current work addresses this gap by developing a dynamic hydrogel system capable of simultaneously increasing stiffness and HA accumulation. This is achieved by a new gelatin macromer permitting sequential thiol-norbornene (for primary network crosslinking) and hydrazone click chemistry (for bioinert or biomimetic stiffening with oxidized dextran (oDex) or oHA, respectively). The results of this study provide new insights into how dynamically changing physicochemical matrix properties guide cancer cell fate processes.

Dataset Information

Cell-mediated delivery of glucocorticoids from thiol-ene hydrogels.

Publications

Cell-mediated delivery of glucocorticoids from thiol-ene hydrogels.

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