Using synchrotron radiation inline phase-contrast imaging computed tomography to visualize three-dimensional printed hybrid constructs for cartilage tissue engineering

Abstract

Synchrotron radiation inline phase-contrast imaging combined with computed tomography (SR-inline-PCI-CT) offers great potential for non-invasive characterization and three-dimensional visualization of fine features in weakly absorbing materials and tissues. For cartilage tissue engineering, the biomaterials and any associated cartilage extracellular matrix (ECM) that is secreted over time are difficult to image using conventional absorption-based imaging techniques. For example, three-dimensional printed polycaprolactone (PCL)/alginate/cell hybrid constructs have low, but different, refractive indices and thicknesses. This paper presents a study on the optimization and utilization of inline-PCI-CT for visualizing the components of three-dimensional printed PCL/alginate/cell hybrid constructs for cartilage tissue engineering. First, histological analysis using Alcian blue staining and immunofluorescent staining assessed the secretion of sulfated glycosaminoglycan (GAGs) and collagen type II (Col2) in the cell-laden hybrid constructs over time. Second, optimization of inline PCI-CT was performed by investigating three sample-to-detector distances (SDD): 0.25, 1 and 3 m. Then, the optimal SDD was utilized to visualize structural changes in the constructs over a 42-day culture period. The results showed that there was progressive secretion of cartilage-specific ECM by ATDC5 cells in the hybrid constructs over time. An SDD of 3 m provided edge-enhancement fringes that enabled simultaneous visualization of all components of hybrid constructs in aqueous solution. Structural changes that might reflect formation of ECM also were evident in SR-inline-PCI-CT images. Summarily, SR-inline-PCI-CT images captured at the optimized SDD enables visualization of the different components in hybrid cartilage constructs over a 42-day culture period.

Evolutionary repression of chondrogenic genes in the vertebrate osteoblast

“…A new(old) vertebrate model for skeletal development: Xenopus tropicalis. (A) A ventral view of a stage NF64 X. tropicalis froglet stained with phosphotungstic acid (PTA) contrast agent and scanned at the Canadian Light Source, the only synchrotron in Canada, using phase-contrast imaging[64,65]. (B) Ventral, (C) dorsal, and (D) lateral views of the craniofacial skeletal structures of a freshly metamorphosed, stage NF66 adult frog made visible through whole-mount Alcian Blue/Alizarin Red staining, where the blue indicates cartilage and red signifies calcified bone.…”

Efficient Fabrication of Polycaprolactone Scaffolds for Printing Hybrid Tissue-Engineered Constructs

“…Novel AM systems with the capacity to print biomaterials and cell-laden hydrogels in a single session have gained much attention for their potential application in the generation of complex human-scale tissue constructs of any shape, such as calvarial bone, cartilage, and skeletal muscle [23,24,25,26]. These so-called “printed hybrid TE constructs” combine 3D scaffolds of complex architectures, cell-laden bioinks extruded in integrated patterns, and microchannels that allow for the diffusion of nutrients and oxygen across the construct.…”

Potential of propagation-based synchrotron X-ray phase-contrast computed tomography for cardiac tissue engineering

“…Several groups have applied X-ray in-line PCI for visualization of tissue-engineered constructs such as polyethylene glycol in water (Brey et al, 2010), poly(glycolic acid)-polyethylene glycol in vitro (Albertini et al, 2009), poly(hydroxy-ester) in water (Appel et al, 2012), poly(l-lactide) and chitosan scaffold in air and water (Zhu et al, 2011) and polycaprolactone-alginate in vitro (Olubamiji et al, 2016). Although the potential of PCI for visualization of soft tissue has shown promise by these previous studies, little has been published for hydrogel-based cardiac tissue engineering.…”