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Osteosarcoma growth on trabecular bone mimicking structures manufactured via laser direct write

pores, a statistical correction factor was used to create the macroporosity of the trabecular bone. The trabecu-
[3]
a more accurate estimate of the actual pore diameter . lar bone exhibits a macroporosity of 300–600 µm and
The average pore diameter for EHA80 PolyHIPE is a porosity of 75–85% [28] . The produced scaffolds have
33.3 μm (mean standard deviation ± 10.6 μm). a strut size of 250 µm and a fibre spacing of 1100 µm,
The woodpile structures presented similar beha- while exhibiting a macroporosity of 82% and a pore size
viour. Increasing the IBOA content increases the sti- of 425 µm (given that the layers are offset by 550 µm).
ffness of the material and reduces the swelling. For These scaffolds have a much higher macroscopic po-
scaffolds with high EHA content, the PolyHIPE can rosity and a larger macroscopic pore size compared to
be freeze dried to prevent the PolyHIPE from shrink- the structures reported in our previous study (58%
ing as it dries [10] . macroporosity and 150 µm pores) [24] . Young’s mod-
Woodpile layered structures from a high internal ulus of the 80% porous material is 1.22 MPa [24] .
phase emulsion are fabricated successively to create
selectively cured regions of PolyHIPE in a stereoli- 3.2 Osteosarcoma Growth
thography-based direct laser writing approach. This In this study, we assessed the growth of human osteo-
was achieved by selectively curing the top layer of a sarcoma (MG-63) on these 3D printed scaffolds. Our
well of the HIPE emulsion, and subsequently adding PolyHIPE structure is based on a mixture of the elas-
layers of the emulsion and curing them to build up an tomer component EHA and the brittle component
object in a layer-by-layer manner (Figure 2). This IBOA (at a 66–33% w/w ratio). These PolyHIPEs are
leads the way for more complex structures to be made. typically produced as monoliths with the pore size
However, increasing the size or number of layers will solely determined by the emulsion templating process.
increase the build time per scaffold. The total build These pore sizes are typically of the order of 10–50 µm,
time per scaffold was less than 10 minutes and the which can impede cell ingrowth and materials transfer.
scaffold parameters were nearly identical by visual To mitigate for this, previous studies used a high water
inspection. The final structures were demonstrated to volume of 90% and an elevated temperature to desta-
[1]
be suitable for 3D cell culture applications and mimic bilise the emulsion for larger pore sizes . In our

Figure 2. (A) Woodpile structure fabricated via single photon direct laser write with dimensions of 0.5 × 0.5 cm, (B) Schematic re-
presentation of the woodpile structure with fibre spacing of 1.1 mm and total dimensions of 0.5 × 0.5 cm. (C–D) Morphology of the
80% nominal porosity EHA PolyHIPE woodpile structure obtained by SEM (scale bar = 500 μm ), (D) Scale bar = 1 mm.

72 International Journal of Bioprinting (2016)–Volume 2, Issue 2