Biocompatibility of α-Al2O3 Ceramic Substrates with Human Neural Precursor Cells

Abstract

Background: Biocompatible materials-topography could be used for the construction of scaffolds allowing the three-dimensional (3D) organization of human stem cells into functional tissue-like structures with a defined architecture. Methods: Structural characterization of an alumina-based substrate was performed through XRD, Brunauer–Emmett–Teller (BET) analysis, scanning electron microscopy (SEM), and wettability measurements. Biocompatibility of the substrate was assessed by measuring the proliferation and differentiation of human neural precursor stem cells (NPCs). Results: α-Al2O3 is a ceramic material with crystallite size of 40 nm; its surface consists of aggregates in the range of 8–22 μm which forms a rough surface in the microscale with 1–8 μm cavities. The non-calcined material has a surface area of 5.5 m2/gr and pore size distribution of 20 nm, which is eliminated in the calcined structure. Thus, the pore network on the surface and the body of the ceramic becomes more water proof, as indicated by wettability measurements. The alumina-based substrate supported the proliferation of human NPCs and their differentiation into functional neurons. Conclusions: Our work indicates the potential use of alumina for the construction of 3D engineered biosystems utilizing human neurons. Such systems may be useful for diagnostic purposes, drug testing, or biotechnological applications.

Fabrication of graded alumina by spark plasma sintering

“…Selecting Al 2 O 3 as model material was reasoned by being produced in the largest quantity among advanced ceramics. Moreover, its application field can be greatly broadened as functionally graded material especially in medicine [20][21][22][23]. The good mechanical properties combined with bioinertness make alumina an appealing material of choice for several medical applications such as bearings in hip replacement [24] or dental implants [25], but a graded microstructure would be an additional advantage.…”

Fabrication and Optimization of 3D-Printed Silica Scaffolds for Neural Precursor Cell Cultivation

“…The cells almost doubled in number within 13 days of culture ( Figure 10 b). We have previously shown that human NPCs cultured on 2D alumina substrates efficiently differentiate into neuronal populations and form a functional neuronal network [ 32 ]. Therefore, NPCs grown on 3D-printed ceramic scaffolds were spontaneously differentiated for 21 days (day 34 post-seeding) as well.…”

“…The in situ XRD was a D8 Advance from Bruker equipped with Cu Ka radiation source from 5–80 2θ angle with 0.04 step and the high temperature oven was a HTK 1200N from Anton Paar. The wetting ability of the ceramic material was measured by the water contact angle method in an in-house contact angle measurement instrument based on a high-resolution sensor camera (Nikon D5600, Tokyo, Japan, AF-P NIKKOR 18–55 mm 1:3.5–5.6 G) according to the arrangement proposed in [ 32 ]. Micro-droplets (2.5 μL) of a double distilled water drop were added manually via a variable volume 0–20 µL Eppendorf Research micropipette.…”

“…RT-qPCR was conducted using the Luna Universal One-Step RT-qPCR Kit (New England Biolabs, Ipswich, MA, USA) according to the manufacturer’s instructions in a Rotor-Gene 6000 (Qiagen, Venlo, The Netherlands) operating system. The primer sequences have been previously described [ 32 ]. The correct size of amplified RT-qPCR products was verified by electrophoresis in a 2% agarose gel.…”

“…On the other hand, oxide ceramic structures such as silica [ 29 , 30 , 31 ], alumina [ 32 , 33 ], and ceria [ 34 , 35 ] synthesized by bottom-up and top-down techniques offer an advantageous scaffold for cell culture, since the porosity and crystallinity of these materials can be tailor controlled providing both adhesion characteristics for uniform cell distribution and improved nutrient exchange while the surface cell deposition allows access for live imaging and in vitro characterization that simulates cells in an organ-like environment. Ceramic scaffolds, apart from the conventional fabrication techniques (e.g., sol-gel, foaming, extrusion, machining, etc., [ 36 , 37 , 38 ]) are often produced using state-of-the-art additive manufacturing techniques, such as 3D printing, that provide high-resolution control over their architecture and complexity [ 4 , 39 ].…”