3D Bioprinting of Hydrogel Scaffold Skin Equivalents for Cosmetic and Drug Testing

Allison Reno

Abstract

Tissue engineering scaffolds are a crucial element of generating larger 3D tissue equivalents for modeling and clinical grafting. Currently, much of scaffold technology has not been significantly updated since the introduction of manually pipetted hydrogels and electrospun fiber scaffolds. Both of these approaches have their advantages and disadvantages, but neither utilize emerging biofabrication techniques such as advanced 3D bioprinting and plotting. In addition to more precision in the outer geometries of the scaffold, the use of bioprinting also introduces the ability to shape hydrogels into very intricate porous inner patterns within the outer geometries. This allows for the design of a highly intricate and advanced network of ECM like material that is highly similar to the real porous environment of tissues, allowing for gas and nutrient exchange similar to that which occurs due to microvasculature of tissues. Additionally, advanced temperature-controlled extrusion bioprinters with UV cure capabilities allow for utilizing very advanced hydrogel materials. These materials can be designed and tailored to maximize their mechanical properties, adhesion, similarity to the natural ECM/basement membrane, and have the ability to be UV cured into very intricate, high resolution, and detailed prints. The unique shapes and materials that can be utilized with advanced 3D extrusion bioprinters significantly improves the adhesion, proliferation, and viability of cells within scaffolds. The use of common tissue engineering hydrogels modified for use as UV cure bioinks allows for precise printing and simple seeding and growth for a robust and advanced scaffold for generation of 3D tissue equivalents. In this dissertation, these technology advancements will be applied to the advancement of 3D skin equivalents for modeling skin for cosmetic and drug testing. Demonstrating both the general efficacy of 3D printing of scaffolds for tissue engineering, and more specifically, the advantages when designing for a specific tissue model, in this case skin equivalents, and how materials, outer geometry, and inner geometry can all be customized to produce an excellent 3D model very similar to the native tissue.