Fabrication of Tissue Engineered Tympanic Membrane Patches Using Computer-Aided Design and Injection Molding

Authors

  • Morgan E. Hott MS,

    1. Center for Tissue Engineering, University of Massachusetts Medical School, Worcester, MA, U.S.A.
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  • Cliff A. Megerian MD,

    1. Department of Otolaryngology, University Hospital of Cleveland, Case Western Reserve University School or Medicine, Cleveland, OH, U.S.A.
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  • Rich Beane MS,

    1. Department of Surgery, University of Massachusetts Medical School, Worcester MA, U.S.A.
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  • Lawrence J. Bonassar PhD

    Corresponding author
    1. Center for Tissue Engineering, University of Massachusetts Medical School, Worcester, MA, U.S.A.
    2. Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, U.S.A.
    • Dr. Lawrence J. Bonassar, Sibley School of Mechanical and Aerospace Engineering, 218 Upson Hall, Cornell University, Ithaca, NY 14853, U.S.A.
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Abstract

Objectives/Hypothesis: The goal of the current study was to use computer-aided design and injection molding technologies to tissue engineer precisely shaped cartilage in the shape of butterfly tympanic membrane patches out of chondrocyte-seeded calcium alginate gels.

Methods: Molds were designed on SolidWorks 2000 and built out of acrylonitrile butadiene styrene (ABS) using fused deposition modeling (FDM). Tympanic membrane patches were fabricated using bovine articular chondrocytes seeded at 50 × 106 cells/mL in 2% calcium alginate gels. Molded patches were cultured in vitro for up to 10 weeks and assessed biochemically, morphologically, and histologically.

Results: Unmolded patches demonstrated outstanding dimensional fidelity, with a volumetric precision of at least 3 μL, and maintained their shape well for up to 10 weeks of in vitro culture. Glycosaminoglycan and collagen content increased steadily over 10 weeks in culture, demonstrating continual deposition of new extracellular matrix consistent with new tissue development.

Conclusions: The use of computer-aided design and injection molding technologies allows for the fabrication of very small, precisely shaped chondrocyte-seeded calcium alginate structures that faithfully maintain their shape during in vitro culture. In vitro fabrication of tympanic membrane patches with a precisely controlled geometry may have the potential to provide a minimally invasive alternative to traditional methods for the repair of chronic tympanic membrane perforations.

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