Stereolithography of Poly(Ethylene Glycol) Hydrogels with Application in Tissue Engineering as Peripheral Nerve Regeneration Scaffolds

In recent years, rapid prototyping (RP) technologies initially developed to create prototypes prior to production for the automotive, aerospace, and other industries, have found applications in tissue engineering (TE). Several different RP technologies are being used to fabricate biocompatible 3D structures with controlled micro- and macro-scale characteristics. The focus of this research was to explore the capabilities of the RP technology, stereolithography (SL), for creating complex, 3D scaffolds with applications in TE using a photocrosslinkable biopolymer, poly(ethylene glycol) (PEG). The primary objective was to create an implantable multi-lumen nerve guidance conduit (NGC) for the regeneration of peripheral nerves. Studies of the photocrosslinking behavior of PEG were performed so that complex structures could be fabricated in a layer-by-layer fashion. The fabrication of multi-material structures with specified spatially-controlled characteristics, mechanical strength and final swollen feature sizes was demonstrated. Several factors related to unfavorable cell growth and survival during SL fabrication were assessed in-vitro using human dermal fibroblast cells. In-vitro studies showed that the SL build parameters that could impact cell survival were well within what would be required to create PEG-based scaffolds with encapsulated living cells. A manufacturing process for multi-lumen PEG-based NGCs was developed. The use of SL in the manufacturing process provides a rapid fabrication technology for complex 3D scaffolds. With the addition of lyophilization and sterilization, the resulting manufacturing process rapidly creates implantable, off-the-shelf products with improved suturability. This research demonstrates that SL represents a unique additive fabrication technology that can create complex 3D TE scaffolds, allowing for control over the scaffold\u27s macro-scale design as well as precise placement of viable cells and bioactive agents within the scaffold during construction