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3D Control of Properties in Single-Material Digital Stereolithography for the Treatment of Pediatric Physeal Injuries

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A predominant challenge in tissue engineering is the need of a robust technique for producing structures with precise three-dimensional control of properties. This is because stem cell differentiation is sensitive to biomechanical cues. We use pediatric physeal tissue engineering as a model application because damaged cartilage within the physis can lead to bone formation and asymmetric growth arrest. The physis has three distinct zones where cells evolve differently depending on the chemical and mechanical environment. Here, we present the first demonstration of micron-scale 3D control of mechanical properties using a single cytocompatible material. Our findings indicate that the mechanical and chemical properties of materials patterned using stereolithography can be programmed by a model that accounts for the non-reciprocal relationship between intensity, time and conversion. In this work, we use a poly (ethylene glycol) diacrylate based hydrogel to implement both a step function and gradual change in mechanical properties in 3D scaffolds on the order of 75 microns. The model is validated by a novel application of atomic force microscopy. As a proof of concept, pillar structures were implanted into a rabbit model of physeal injury and there was an apparent reduction in bony bar reformation after eight weeks of implantation.

Learning Objectives:

  • Describe predictive models of chemical and mechanical properties that can be translated into tissue engineering microstructures that match the biomechanical environment of native tissue
  • Understand the limitations of 3D property control in digital stereolithography and how to overcome them
  • Fabricate structures that are close to final properties and require minimal post-processing