A 2018/2019 Summer Studentship research project
Oxygen serves as a fundamental signalling molecule for normal cellular functions, making oxygen control in cartilage 3D-bioprinting a prerequisite for generating high quality tissue and overcoming the challenges of fabricating clinically relevant construct sizes with homogenous and healthy cartilage tissue formation.
Student: James Swan
Supervisors: Dr Gabriella Lindberg, Dr Khoon Lim, Associate Professor Tim Woodfield
Sponsor: TBC
Project brief
Introduction
3D-Bioprinting of tissue engineered constructs is a prospective source of advanced therapy to heal damaged cartilage tissue. Within these 3D cellular microenvironments, oxygen is known to be a central and powerful component serving as both a metabolic substrate and as a signaling molecule. The oxygen availability within 3D-bioprinted constructs is, however, mainly present by diffusion, and as oxygen is consumed by cells it may further form oxygen gradients, either enhancing or restricting the cellular development. These mass transfer limitations arguably remain the biggest challenge in the field of tissue engineering, typically confining construct sizes to smaller than clinically relevant dimensions in order to maintain adequate nutrient and oxygen transportation. There is thus a need for a better understanding of the internal diffusion profiles over time within 3D-bioprinted cartilage constructs to successfully support healthy cellular development in clinical relevant sized constructs. We seek to systematically investigate and control the oxygen gradients in cell-laden scaffolds bioprinted utilizing three distinct 3D-technology platforms: extrusion based 3D-printing, oil-emulsion microfluidics and sacrificial 3D-printing.
Aim
This project aims to control the distribution of oxygen in 3D-printed cartilage constructs by optimising architectural designs using three distinct technology platforms.
Method
Cell-laden bioinks will be 3D-bioprinted using three distinct technologies: extrusion based 3D-printing (Bioscaffolder, Sys+Eng), oil-emulsion microfluidics and sacrificial 3D-printing (Pluronic F127) and subsequently crosslinked using light activated gelatin hydrogel platforms uniquely developed in the Christchurch Regenerative Medicine and Tissue Engineering (CReaTE) research group. Living cartilage constructs with varying architectures (strand and spheres), size distributions (200µm–1500µm) and network interconnectivity (strand spacing and thickness) will be systematically 3D-bioprinted to study the effect on oxygen diffusion to and from the cells using optical oxygen microsensors (Presens® profiling system). Cellular health will furthermore be assessed using cell viability (Live/Dead®) and metabolic activity assays (AlamarBlue®). The techniques and assays required to be carried out for the project are routinely conducted in the CReaTE group.
Student researcher’s component of the study
The student will be involved in fabricating and evaluating the effect of 3D-bioprinting strategies, and subsequent architectures (varying size, shape, and network interconnectivity) on oxygen gradients in 3D-bioprinted cartilage constructs. The student will independently seek to optimise scaffold architectures and cell culture conditions to better match the oxygen distribution profile in native cartilage to help drive the formation of healthy tissue and maintain viable cells in larger, clinically relevant sized, tissue engineered constructs.
