Thursday June 30, 2005
Friday July 1, 2005

"Controlling three-dimensional cellular organization and growth using a composite polydimethylsiloxane-collagen tissue scaffold"
Mr. James Norman
Boston University

The use of microfabrication and nanofabrication techniques for creating tissue engineering scaffolds has allowed researchers to gain greater control over many aspects of artificial tissues. Near UV photolithography and replica molding have allowed for the creation of substrates with features that are designed to provide a growth environment that can lead cells to organize in a manner that more closely mimics in vivo tissue architecture. To date, these techniques have been used mainly for creating organized two-dimensional artificial tissues. It has been shown with these systems that this 2-D organization can create cultures that more accurately reflect native tissue properties. Control over cellular organization in three-dimensions has been harder to achieve due to the complexity of creating precisely featured three-dimensional scaffolds. Three-dimensional tissue cultures are typically grown in natural biopolymers, such as collagen, where the cells are mixed in and allowed to grow. This simple 3-D method has also been shown to influence cells to behave more naturally; however, this method provides no control over the organization of the cells. We have combined these two techniques to create a three-dimensional composite polydimethylsiloxane (PDMS)-Type I collagen scaffold. A scaffold of high aspect ratio channels were created in SU-8 negative photoresist which was then replica molded to recreate the design in PDMS. A fibroblast seeded collagen gel was then molded around this PDMS scaffold. The PDMS scaffold acted like an internal skeleton to organize the cells into longitudinally aligned bundles though out the height of the collagen gel. Using this technique the cells gain the organization provided by the fabricated scaffold as well as a more natural growth environment and 3-D support provided by the collagen gel. Organization of the cell population was analyzed as well as the scaffolds effects on nanoscale cellular components such as F-actin filaments and the focal adhesion protein vinculin.