Oxygen diffusion in marine-derived tissue engineering scaffolds

Fabrication and characterization of Ag- and Ga-doped mesoporous glass-coated scaffolds based on natural marine sponges with improved mechanical properties

Natural marine sponges were used as sacrificial template for the fabrication of bioactive glass-based scaffolds. After sintering at 1050°C, the resulting samples were additionally coated with a silicate solution containing biologically active ions (Ag and Ga), well-known for their antibacterial properties. The produced scaffolds were characterized by superior mechanical properties (maximum compressive strength of 4 MPa) and total porosity of ~80% in comparison to standard scaffolds made by using PU foam templates. Direct cell culture tests performed on the uncoated and coated samples showed positive results in terms of adhesion, proliferation, and differentiation of MC3T3-E1 cells. Moreover, vascular endothelial growth factor (VEGF) secretion from cells in contact with scaffold dissolution products was measured after 7 and 10 days of incubation, showing promising angiogenic results for bone tissue engineering applications. The antibacterial potential of the produced samples was assessed by performing agar diffusion tests against both Gram-positive and Gram-negative bacteria.

Indirect 3D printing technology for the fabrication of customised β-TCP/chitosan scaffold with the shape of rabbit radial head-an in vitro study

Background

With the development of indirect three-dimensional (3D) printing technology, it is possible to customise individual scaffolds to be used in bone transplantation and regeneration. In addition, materials previously limited to the 3D printing (3DP) process due to their own characteristics can also be used well in indirect 3DP. In this study, customised β-TCP/chitosan scaffolds with the shape of rabbit radial head were produced by indirect 3D printing technology.

Methods

Swelling ability, porosity, mechanical characterisation, and degradation rate analysis were performed, and in vitro studies were also implemented to evaluate the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells (MSCs) on the scaffolds. CCK8 cell proliferation assay kit and alkaline phosphatase (ALP) staining solution were used to study cell proliferation and early ALP content at the scaffold surface. Moreover, the osteogenic differentiation of MSCs on scaffolds was also evaluated through the scanning electron microscopy analysis.

Results

β-TCP/chitosan scaffold has good performance and degradation rate, and in vitro cell experiments also confirm that the scaffold has adequate cytocompatibility and bioactivity.

Conclusion

This study provides a promising new strategy for the design of customised scaffolds for the repair of complex damaged tissues.

Bioactivity and Mechanical Stability of 45S5 Bioactive Glass Scaffolds Based on Natural Marine Sponges

Bioactive glass (BG) based scaffolds (45S5 BG composition) were developed by the replica technique using natural marine sponges as sacrificial templates. The resulting scaffolds were characterized by superior mechanical properties (compression strength up to 4 MPa) compared to conventional BG scaffolds prepared using polyurethane (PU) packaging foam as a template. This result was ascribed to a reduction of the total scaffold porosity without affecting the pore interconnectivity (>99%). It was demonstrated that the reduction of total porosity did not affect the bioactivity of the BG-based scaffolds, tested by immersion of scaffolds in simulated body fluid (SBF). After 1 day of immersion in SBF, a homogeneous CaP deposit on the surface of the scaffolds was formed, which evolved over time into carbonate hydroxyapatite (HCA). Moreover, the enhanced mechanical properties of these scaffolds were constant over time in SBF; after an initial reduction of the maximum compressive strength upon 7 days of immersion in SBF (to 1.2 ± 0.2 MPa), the strength values remained almost constant and higher than those of BG-based scaffolds prepared using PU foam (<0.05 MPa). Preliminary cell culture tests with Saos-2 osteoblast cell line, namely direct and indirect tests, demonstrated that no toxic residues remained from the natural marine sponge templates and that cells were able to proliferate on the scaffold surfaces.

Osteogenic cell response to 3-D hydroxyapatite scaffolds developed via replication of natural marine sponges

Bone tissue engineering may provide an alternative to autograft, however scaffold optimisation is required to maximize bone ingrowth. In designing scaffolds, pore architecture is important and there is evidence that cells prefer a degree of non-uniformity. The aim of this study was to compare scaffolds derived from a natural porous marine sponge (Spongia agaricina) with unique architecture to those derived from a synthetic polyurethane foam. Hydroxyapatite scaffolds of 1 cm(3) were prepared via ceramic infiltration of a marine sponge and a polyurethane (PU) foam. Human foetal osteoblasts (hFOB) were seeded at 1 × 10(5) cells/scaffold for up to 14 days. Cytotoxicity, cell number, morphology and differentiation were investigated. PU-derived scaffolds had 84-91% porosity and 99.99% pore interconnectivity. In comparison marine sponge-derived scaffolds had 56-61% porosity and 99.9% pore interconnectivity. hFOB studies showed that a greater number of cells were found on marine sponge-derived scaffolds at than on the PU scaffold but there was no significant difference in cell differentiation. X-ray diffraction and inductively coupled plasma mass spectrometry showed that Si ions were released from the marine-derived scaffold. In summary, three dimensional porous constructs have been manufactured that support cell attachment, proliferation and differentiation but significantly more cells were seen on marine-derived scaffolds. This could be due both to the chemistry and pore architecture of the scaffolds with an additional biological stimulus from presence of Si ions. Further in vivo tests in orthotopic models are required but this marine-derived scaffold shows promise for applications in bone tissue engineering.