In vivo Stability of Poly(ethylene glycol)-Collagen Composites

Rhee, Woonza; Rosenblatt, Joel; Castro, Marisol; Schroeder, J. A.; Rao, Prema R.; Harner, Carol F. H.; Berg, Richard A.

doi:10.1021/bk-1997-0680.ch026

Cited by 10 publications

(6 citation statements)

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“…This study investigated the ability of modular scaffolds composed of PEG microgels crosslinked via collagen I, which influences cell attachment and expression [25, 26], to encourage and support neuronal cells. We first characterized the PEG microgels including the fabrication process and the formation and physical properties of the modugels.…”

Section: Introductionmentioning

confidence: 99%

Modular poly(ethylene glycol) scaffolds provide the ability to decouple the effects of stiffness and protein concentration on PC12 cells

2011

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This research focused on developing a modular poly(ethylene glycol) (PEG) scaffold, assembled from PEG microgels and collagen I, to provide an environment to decouple the chemical and mechanical cues within a three dimensional scaffold. We first characterized the microgel fabrication process, examining the size, polydispersity, swelling ratio, mesh size, and storage modulus of the polymer particles. The resulting microgels had a low polydispersity, PDI=1.08, and a diameter of ~1.6 μm. The mesh size of the microgels, calculated from the swelling ratio, was 47.53 Å. Modular hydrogels (modugels) were then formed by compacting EDC/NHS activated microgels with PEG-4arm-amine and 0, 1, 10, or 100 μg/mL collagen. Stiffness (G*) of the modugels was not significantly altered with the addition of collagen, allowing for modification of the chemical environment independent from the mechanical properties of the scaffold. PC12 cell aggregation increased in modugels as collagen concentrations increased and cell viability in modugels was improved over bulk PEG hydrogels. Overall, these results indicate that further exploration of modular scaffolds formed from microgels could allow for a better understanding of the relationship between the chemical and mechanical properties and cellular behavior.

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Section: Introductionmentioning

confidence: 99%

Modular poly(ethylene glycol) scaffolds provide the ability to decouple the effects of stiffness and protein concentration on PC12 cells

2011

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“…These gels can be manipulated via the concentration of PEG,11 with previous studies demonstrating that increased PEG concentrations led to corresponding increases in the mechanical properties of the gel 19, 20. In addition, PEG is a readily chemically modified21–23 and, therefore, the chemical nature of the scaffold can be altered through the conjugation of ECM proteins21 or peptide sequences20 into the gel to influence cell growth 24…”

Section: Introductionmentioning

confidence: 99%

“…For example, by conjugating the collagen directly into the gel, the protein can be homogeneously distributed within the gel. In addition, as collagen I directly interacts with cell surface receptors and influences cell attachment, proliferation, and expression,9 the incorporation of this protein will provide chemical cues necessary for cell growth 20, 21, 23. Gunn et al found that a neural cell model, PC12 cells, seeded on top of PEG gels with added RGDS, an amino acid sequence that serves as a cell recognition site for the binding of ECM, were able to extend neurites in 11.4% ± 1.2% of cells, with better extension on gels with lower mechanical properties 20.…”

Section: Introductionmentioning

confidence: 99%

Characterization of poly(ethylene glycol) gels with added collagen for neural tissue engineering

Scott¹,

Marquardt²,

Willits³

2010

J Biomedical Materials Res

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Over the past decade, it has been increasingly recognized that both chemical and mechanical properties of scaffolds influence neural cell behavior, ranging from growth to differentiation to migration. However, mechanical properties are difficult to control for in the design of scaffolds for nerve regeneration, as properties change over time for most biologically derived scaffolds. The focus of this project was to examine how the mechanical properties of a nondegradable scaffold, poly(ethylene glycol) (PEG) gels, influenced nerve cell behavior. Low concentration PEG gels, of 3, 4, or 5% PEG, with added collagen to alter chemical properties were examined for both their mechanical properties and their ability to support nerve expression and extension. Stiffness (G*) significantly increased with increased PEG concentration. The addition of chemically conjugated collagen significantly decreased the stiffness compared to plain gels. This phenomenon was confirmed to be an effect of the conjugate, and not the protein itself, as G* of gels containing conjugate, but no protein, was not significantly different than G* of gels with conjugated protein. PC12 cell neurite expression increased with decreasing PEG and increasing collagen concentration. At its best, the expression approached the value on collagen-coated tissue culture plastic, which is a substantial improvement over previous studies on PEG. Neurite extension of dorsal root ganglia was also improved on these same gels over gels with either higher PEG concentration or lower collagen amount. Overall, these results suggest that exploration of lower stiffness materials is necessary to improve neurite growth and extension in three-dimensional synthetic scaffolds.

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“…For example, polyethylene glycol (PEG)/collagen composites have been used as an improved resorbable hemostatic bone wax. 8 Collagen/PEG conjugates have been used as scaffolds for connective tissue reconstruction 9,10 ; the synthetic polymers stabilize the porous structure of collagen and decrease its immunogenicity. Mammalian cells can be encapsulated in polymer carriers and have been tested as replacements for brain, 11 liver, 12,13 skin 14,15 blood vessels, 16 cartilage, 17,18 and endocrine organs.…”

Section: Introductionmentioning

confidence: 99%

Influence of synthetic polymers on neutrophil migration in three-dimensional collagen gels

Tan

Saltzman

1999

J. Biomed. Mater. Res.

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In vitro studies of cell migration within three-dimensional polymeric materials are essential for understanding cell behavior and for developing new biomedical materials. Human neutrophil motility was examined in hydrated collagen gels containing various synthetic polymers. Physical mixtures of collagen and certain water-soluble polymers formed stable gels that were good substrates for cell migration. Addition of either polyethylene glycol (PEG) or the pluronictrade mark copolymer F68 did not change the morphological or mechanical properties of collagen gels, as determined by SEM and oscillatory rheometry; however, addition of either polymer significantly inhibited cell motility in both a modified 96-well chemotaxis chamber assay and a direct visual assay. Although the mechanism for this observed polymer inhibition of neutrophil migration is not yet clear, these results suggest that PEG and F68, two widely used biomedical polymers that are considered to be relatively "inert," may cause significant inhibition of cell motility.

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In vivo Stability of Poly(ethylene glycol)-Collagen Composites

Cited by 10 publications

References 0 publications

Modular poly(ethylene glycol) scaffolds provide the ability to decouple the effects of stiffness and protein concentration on PC12 cells

Modular poly(ethylene glycol) scaffolds provide the ability to decouple the effects of stiffness and protein concentration on PC12 cells

Characterization of poly(ethylene glycol) gels with added collagen for neural tissue engineering

Influence of synthetic polymers on neutrophil migration in three-dimensional collagen gels

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