Ceramic scaffolds produced by computer‐assisted 3D printing and sintering: Characterization and biocompatibility investigations

Abstract

Hydroxyapatite (HAP) and tricalcium phosphate (TCP) are two very common ceramic materials for bone replacement. However, in general HAP and TCP scaffolds are not tailored to the exact dimensions of the defect site and are mainly used as granules or beads. Some scaffolds are available as ordinary blocks, but cannot be customized for individual perfect fit. Using computer-assisted 3D printing, an emerging rapid prototyping technique, individual three-dimensional ceramic scaffolds can be built up from TCP or HAP powder layer by layer with subsequent sintering. These scaffolds have precise dimensions and highly defined and regular internal characteristics such as pore size. External shape and internal characteristics such as pore size can be fabricated using Computer Assisted Design (CAD) based on individual patient data. Thus, these scaffolds could be designed as perfect fit replacements to reconstruct the patient's skeleton. Before their use as bone replacement materials in vivo, in vitro testing of these scaffolds is necessary. In this study, the behavior of human osteoblasts on HAP and TCP scaffolds was investigated. The commonly used bone replacement material BioOss(R) served as control. Biocompatibility was assessed by scanning electron microscopy (SEM), fluorescence microscopy after staining for cell vitality with fluorescin diacetate (FDA) and propidium iodide (PI) and the MTT, LDH, and WST biocompatibility tests. Both versions were colonised by human osteoblasts, however more cells were seen on HAP scaffolds than TCP scaffolds. Cell vitality staining and MTT, LDH, and WST tests showed superior biocompatibility of HAP scaffolds to BioOss, while BioOss was more compatible than TCP. Further experiments are necessary to determine biocompatibility in vivo. Future modifications of 3D printed scaffolds offer advantageous features for Tissue Engineering. The integration of channels could allow for vascular and nerve ingrowth into the scaffold. Also the complex shapes of convex and concave articulating joint surfaces maybe realized with these rapid prototyping techniques.

3D Printing of Personalized Artificial Bone Scaffolds

“…The final part consists of 24 ) that can not only wet the surrounding powder, but also locally harden the wetted area. 25,26 Binder drop volume and wettability are important parameters to consider before printing. Binder wettability influences the green strength (the initial strength after printing but before postprocessing steps) of the printed object, and is directly related to the powder particle surface energy, chemistry, and binder viscosity.…”

3D Miniaturization of Human Organs for Drug Discovery

“…High-throughput pharmacological study [36,78] 3D bioprinting Primary feline H1 cardiomyocytes First rhythmic beating of 3D printed structure [93][94][95] Lung Microfabrication Epithelial cells Use of porous membrane to mimic lung functions [31,37] 3D bioprinting A549 cells and EA hy926 cells World's first 3D bioprinted lung tissue [101] Bone 3D bioprinting BMSCs High viability in microextrusion-based bioprinting [108,109,158,159] Cancer Self-assembled Intestinal stem cells Discovery of LGR5+ intestinal stem cells [52,62] Microfabrication Breast cancer cells Perfusable human microvascularized bone-mimicking (BMi) microenvironment [81,168] 3D bioprinting OVCAR-5 and MRC-5 cells Insight into complex cell-cell communication in 3D [113][114][115][116][117] Multi Self-assembled Liver, gut, vessel cells High throughput hanging drop [30,[49][50][51][52] Microfabrication Liver, heart, and vessel cells Automated control of perfusion [11,19,27,32] 3D bioprinting NPC and HCT-116 cells Multiorgan bioprinted model [30,122] a)…”

“…Nevertheless, 3D bioprinted bone systems have been developed. [108,158,159] Campbells and co-workers fabricated bone tissue by stimulating growth factor dose-dependent differentiation of MDSC's toward osteogenic phenotype using jet-based bioprinting of BMP-2 patterns. [109] Primary muscle-derived stem cells were cultured on BMP-2 patterns bioprinted on fibrin substrates.…”

Bioceramic Scaffolds

“…One of the important benefits of this method is the powder bed support by itself for each successive layer. The fragility of the obtained parts is considered a drawback [81][82][83][84][85][86][87][88].…”