Gene delivery to overcome astrocyte inhibition of axonal growth: An in vitro Model of the glial scar

Authors

  • Hannah M. Tuinstra,

    1. Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Rd, Tech E136, Evanston, Illinois 60208; telephone: 847-491-7043; fax: 847-491-3728
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  • Melissa M. Ducommun,

    1. Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Rd, Tech E136, Evanston, Illinois 60208; telephone: 847-491-7043; fax: 847-491-3728
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  • William E. Briley,

    1. Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Rd, Tech E136, Evanston, Illinois 60208; telephone: 847-491-7043; fax: 847-491-3728
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  • Lonnie D. Shea

    Corresponding author
    1. Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Rd, Tech E136, Evanston, Illinois 60208; telephone: 847-491-7043; fax: 847-491-3728
    2. The Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Galter Pavilion, 675 N. Saint Clair, 21st Floor, Chicago, Illinois 60611
    3. Institute for BioNanotechnology in Medicine, Northwestern University, Chicago, Illinois 60611
    4. Chemistry of Life Processes Institute, Northwestern University, Chicago, Illinois 60618
    • Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Rd, Tech E136, Evanston, Illinois 60208; telephone: 847-491-7043; fax: 847-491-3728
    Search for more papers by this author

Abstract

After injury to the central nervous system, a glial scar develops that physically and biochemically inhibits axon growth. In the scar, activated astrocytes secrete inhibitory extracellular matrix, of which chondroitin sulfate proteoglycans (CSPGs) are considered the major inhibitory component. An inhibitory interface of CSPGs forms around the lesion and prevents axons from traversing the injury, and decreasing CSPGs can enhance axon growth. In this report, we established an in vitro interface model of activated astrocytes and subsequently investigated gene delivery as a means to reduce CSPG levels and enhance axon growth. In the model, a continuous interface of CSPG producing astrocytes was created with neurons seeded opposite the astrocytes, and neurite crossing, stopping, and turning were evaluated as they approached the interface. We investigated the efficacy of lentiviral delivery to degrade or prevent the synthesis of CSPGs, thereby removing CSPG inhibition of neurite growth. Lentiviral delivery of RNAi targeting two key CSPG synthesis enzymes, chondroitin polymerizing factor and chondroitin synthase-1, decreased CSPGs, and reduced inhibition by the interface. Degradation of CSPGs by lentiviral delivery of chondroitinase also resulted in less inhibition and more neurites crossing the interface. These results indicate that the interface model provides a tool to investigate interventions that reduce inhibition by CSPGs, and that gene delivery can be effective in promoting neurite growth across an interface of CSPG producing astrocytes. Biotechnol. Bioeng. 2013; 110: 947–957. © 2012 Wiley Periodicals, Inc.

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