Hierarchical bone scaffolds with integrated trabecular topology and lacuno-canalicular connectivity modulate fluid dynamics and support osteogenic culture.

Abstract

The hierarchical structure of bone governs both mechanical behavior and mechanobiological signaling, yet most Bone Tissue Engineering (BTE) scaffolds reproduce only meso-scale porosity while neglecting the Lacuno-Canalicular Network (LCN), a key regulator of interstitial fluid flow. Here, we present a multi-scale bio-inspired scaffold integrating synchrotron μ-CT-derived trabecular architecture with a computationally engineered LCN-like micro-porosity. Two micro-network topologies, Regular and Canalicular-like, were fabricated via two-photon polymerization using IP-VISIO, here applied for the first time in a BTE context. Computational fluid dynamics revealed topology-dependent transport behavior: the Canalicular-like architecture exhibited >40% higher permeability and more homogeneous wall shear stress distributions within osteogenic-relevant ranges compared to the Regular design. Human bone marrow-derived mesenchymal stromal cells were cultured onto scaffolds under static conditions, showing cell attachment, osteogenic gene expression, and mineralized matrix deposition in both designs, assessed by SEM, RT-qPCR and Alizarin Red S staining. Synchrotron μ-CT showed mineral deposition throughout both trabecular regions and the engineered micro-network, with a more uniform spatial distribution in the Canalicular-like scaffold. Overall, this work proposes a multi-scale design framework and identifies LCN-inspired micro-architecture as a promising design variable for hierarchical bone scaffolds, influencing predicted fluid-dynamic behavior and supporting osteogenic culture.