ABSTRACT Design of a Three-Dimensional Composite Scaffold with Varied Engineered Micro-Architecture Wettergreen, MA, Mikos AG, Liebschner, MAK Department of Bioengineering, Rice University, Houston, TX. liebschner@rice.edu The ultimate goal for tissue engineers is the design and complete control of a three-dimensional scaffold for use in implantation. Through the use of microfluidics, soft lithography, and other patterning methods, the two-dimensional environment can be modified and engineered to specifications based upon the intended use for the scaffold. While the two-dimensional surfaces modified in laboratory experiments are far from mimicking the existing environment of the body, it is hoped that the use of these techniques will soon provide a breakthrough allowing researchers to expand upon current techniques and generate a three-dimensional model of tissue. Current rapid prototyping methods for the generation of three-dimensional scaffolds utilize molds designed for only one material, creating scaffolds which are isotopic throughout. Joints in the human body, however, are composed of several distinct regions with varied material properties. As such, scaffold generation methods should incorporate multiple materials with different mechanical properties, creating constructs which better imitate the native tissue. The goal of this study is to develop a novel process for the fabrication of an engineered scaffold with distinct regions, each consisting of different materials for the creation of a scaffold mimicking the Temporomandibular joint (TMJ) disc (see Fig 1). The TMJ disc is a donut shaped structure containing three distinct regions, each with differing mechanical properties (see Table 1). Using a combination of rapid prototyping and molding techniques, a three-dimensional scaffold with varied architecture is built utilizing multiple materials possessing drastically different material properties. Using computer aided design and Finite Element Modeling, the architecture (based on regular polyhedra) of each region will be tailored to the mechanical property requirements of the region. The resulting construct has diverse mechanical characteristics that mimic the mechanical strength of the TMJ disc. The results of this study represent the first step in the complete control over the three-dimensional environment of a scaffold. The distinct architectures created in the scaffold will offer variability in mechanical strength and porosity. The different materials used in the fabrication vary in their cell attachment and degradation times. Using this same technique, design of other three-dimensional scaffolds can be accomplished.

1. Design of a Three-Dimensional Composite Scaffold with Varied Engineered Micro-Architecture Matthew A Wettergreen, Mark D Timmer, Antonios G Mikos, Michael AK Liebschner 13 th GRIBOI March 14 th , 2003 Rice University Computational and Experimental Biomechanics Laboratory

10. Excision of TMJ Disc

11. Creation of TMJ Disc Positive CAD file of scanned disc Rapid Prototyped disc Excised Porcine disc μ CT slice of disc

14. Scaffold Generation Completed Scaffold with 1,3 Butane… & PPF-DA Blue light for crosslinking Inject material Crosslink material Inject 2 nd material

18. /3

26. Thank you