Inversely 3D-Printed β-TCP Scaffolds for Bone Replacement.

Michael Seidenstuecker,Rainer Gadow,Sergio H Latorre,Steffen Esslinger,Rumen Krastev,Anke Bernstein,Hermann O Mayr,Svenja Lange

doi:10.3390/ma12203417

Michael Seidenstuecker, Rainer Gadow + Show 6 more

Open Access

https://doi.org/10.3390/ma12203417

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Abstract

The aim of this study was to predefine the pore structure of β-tricalcium phosphate (β-TCP) scaffolds with different macro pore sizes (500, 750, and 1000 µm), to characterize β-TCP scaffolds, and to investigate the growth behavior of cells within these scaffolds. The lead structures for directional bone growth (sacrificial structures) were produced from polylactide (PLA) using the fused deposition modeling techniques. The molds were then filled with β-TCP slurry and sintered at 1250 °C, whereby the lead structures (voids) were burnt out. The scaffolds were mechanically characterized (native and after incubation in simulated body fluid (SBF) for 28 d). In addition, biocompatibility was investigated by live/dead, cell proliferation and lactate dehydrogenase assays. The scaffolds with a strand spacing of 500 µm showed the highest compressive strength, both untreated (3.4 ± 0.2 MPa) and treated with simulated body fluid (2.8 ± 0.2 MPa). The simulated body fluid reduced the stability of the samples to 82% (500), 62% (750) and 56% (1000). The strand spacing and the powder properties of the samples were decisive factors for stability. The fact that β-TCP is a biocompatible material is confirmed by the experiments. No lactate dehydrogenase activity of the cells was measured, which means that no cytotoxicity of the material could be detected. In addition, the proliferation rate of all three sizes increased steadily over the test days until saturation. The cells were largely adhered to or within the scaffolds and did not migrate through the scaffolds to the bottom of the cell culture plate. The cells showed increased growth, not only on the outer surface (e.g., 500: 36 ± 33 vital cells/mm² after three days, 180 ± 33 cells/mm² after seven days, and 308 ± 69 cells/mm² after 10 days), but also on the inner surface of the samples (e.g., 750: 49 ± 17 vital cells/mm² after three days, 200 ± 84 cells/mm² after seven days, and 218 ± 99 living cells/mm² after 10 days). This means that the inverse 3D printing method is very suitable for the presetting of the pore structure and for the ingrowth of the cells. The experiments on which this work is based have shown that the fused deposition modeling process with subsequent slip casting and sintering is well suited for the production of scaffolds for bone replacement.

Highlights

Bone disorders and defects continue to increase in our society
Figure shows two views of the scaffold, exemplary atweighed the scaffold with the 500 μm pore size
The results show that the resistance of the 500 μm scaffolds was highest at 3.4 ± 0.2 MPa

Summary

Introduction

Bone disorders and defects continue to increase in our society. The reason for this is the increasing average age of the population [1]. Its difficulty lies in producing complex structures on a scale necessary for human application [4]. These scaffolds are usually made of biodegradable materials with different porosities [1,5]. All, they provide mechanical support during the repair or regeneration processes of the bone. Since the biomechanical systems of bones is complex, scaffolds used to treat bone defects must meet certain requirements: Biocompatibility, mechanical properties, and pore size [6]

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