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Hydrogel properties influence ECM production by chondrocytes photoencapsulated in poly(ethylene glycol) hydrogels

Authors

  • Stephanie J. Bryant,

    1. Department of Chemical Engineering, University of Colorado, Boulder, Colorado 80309-0424
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  • Kristi S. Anseth

    Corresponding author
    1. Department of Chemical Engineering, University of Colorado, Boulder, Colorado 80309-0424
    2. Howard Hughes Medical Institute, Chevy Chase, Maryland 20815-6789
    • Department of Chemical Engineering, University of Colorado, Boulder, Colorado 80309-0424
    Search for more papers by this author

Abstract

When using hydrogel scaffolds for cartilage tissue engineering, two gel properties are particularly important: the equilibrium water content (q, equilibrium swelling ratio) and the compressive modulus, K. In this work, chondrocytes were photoencapsulated in degrading and nondegrading poly(ethylene glycol)-based hydrogels to assess extracellular matrix (ECM) formation as a function of these gel properties. In nondegrading gels, the glycosaminoglycan (GAG) content was not significantly different in gels when q was varied from 4.2 to 9.3 after 2 and 4 weeks in vitro. However, gels with a q of 9.3 allowed GAGs to diffuse throughout the gels homogenously, but a q ≤ 5.2 resulted in localization of GAGs pericellularly. Interestingly, in the moderately crosslinked gels with a K of 360 kPa, an increase in type II collagen synthesis was observed compared with gels with a higher (960 kPa) and lower (30 kPa) K after 4 weeks. With the incorporation of degradable linkages into the network, gel properties with an initially high K (350 kPa) and final high q (7.9) were obtained, which allowed for increased type II collagen synthesis coupled with a homogenous distribution of GAGs. Thus, a critical balance exists between gel swelling, mechanics, and degradation in forming a functional ECM. © 2001 Wiley Periodicals, Inc. J Biomed Mater Res 59: 63–72, 2002

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