Triply Periodic Minimal Surface-Based Scaffolds for Bone Tissue Engineering: A Mechanical, In Vitro and In Vivo Study

Abstract

Triply periodic minimal surfaces (TPMSs) are found to be promising microarchitectures for bone substitutes owing to their low weight and superior mechanical characteristics. However, existing studies on their application are incomplete because they focus solely on biomechanical or in vitro aspects. Hardly any in vivo studies where different TPMS microarchitectures are compared have been reported. Therefore, we produced hydroxyapatite-based scaffolds with three types of TPMS microarchitectures, namely Diamond, Gyroid, and Primitive, and compared them with an established Lattice microarchitecture by mechanical testing, 3D-cell culture, and in vivo implantation. Common to all four microarchitectures was the minimal constriction of a sphere of 0.8 mm in diameter, which earlier was found superior in Lattice microarchitectures. Scanning by μCT revealed the precision and reproducibility of our printing method. The mechanical analysis showed significantly higher compression strength for Gyroid and Diamond samples compared with Primitive and Lattice. After in vitro culture with human bone marrow stromal cells in control or osteogenic medium, no differences between these microarchitectures were observed. However, from the TPMS microarchitectures, Diamond- and Gyroid-based scaffolds showed the highest bone ingrowth and bone-to-implant contact in vivo . Therefore, Diamond and Gyroid designs appear to be the most promising TPMS-type microarchitectures for scaffolds produced for bone tissue engineering and regenerative medicine. Impact Statement Extensive bone defects require the application of bone grafts. To match the existing requirements, scaffolds based on triply periodic minimal surface (TPMS)–based microarchitectures could be used as bone substitutes. This work is dedicated to the investigation of mechanical and osteoconductive properties of TPMS-based scaffolds to determine the influencing factors on differences in their behavior and choose the most promising design to be used in bone tissue engineering.

Functionalization of Ceramic Scaffolds with Exosomes from Bone Marrow Mesenchymal Stromal Cells for Bone Tissue Engineering

“…Scaffold architecture also played a role in cell metabolism, although no differences in differentiation were found. This aligns with our prior findings, highlighting the superior characteristics of scaffolds based on triply periodic minimal surfaces [14]. Moreover, Gyroid scaffolds were shown to facilitate the slower release of exosomes, possibly due to their increased material and surface area, impacting solution distribution within the microporosity of the architecture.…”

“…The perfect scaffold should satisfy the biological and mechanical requirements of the target tissue, have an appropriate microstructure and open-pore geometry to promote cell proliferation, migration, and differentiation of cells into the specific cell type, and exhibit suitable surface morphology [12,13]. As shown in our previous study [14],…”

Design, In Vitro Evaluation and In Vivo Biocompatibility of Additive Manufacturing Three-Dimensional Printing of β beta-Tricalcium Phosphate Scaffolds for Bone Regeneration

“…Currently, the concept of the triply periodic minimal surface (TPMS) designs is being transferred to bone matrices as an interesting option. TPMSs are infinite surfaces with periodicity in three dimensions, with no self-intersections and zero mean curvature [31].…”

TPMS Microarchitectures for Vertical Bone Augmentation and Osteoconduction: An In Vivo Study

“…In the context of bone tissue engineering, the microarchitecture of a bone substitute defines pores and interconnections as it represents the distribution of the material in the macroarchitecture, which occupies the space of the bone defect [ 2 ]. The advent of additive manufacturing has revolutionized the production of highly defined porous, personalized bone substitutes for bone tissue engineering [ 2 ], including the highly complex TPMS microarchitectures [ 16 ] and the adaptive density minimal surface (ADMS) microarchitectures [ 17 ]. Additive manufacturing also facilitated the production of honeycomb-based scaffolds for bone augmentation [ 18 ].…”

“…D-diamond designs of titanium scaffolds yielded good bone regeneration in femurs but poor results in cranial defects [ 27 ]. Nevertheless, to our knowledge, there are no comparative studies with scaffolds based on different types of TPMS microarchitectures besides our recent study on osteoconduction of TPMS microarchitectures with a common bottleneck diameter of 0.8 mm [ 16 ].…”