Agathe Heyraud

This article addresses the unmet clinical need of scaffolds for bone regeneration that can combine osteogenic properties, such as the promotion of bone marrow stem cell differentiation into osteoblasts, with the ability to withstand cyclic loading. In our previous study, we demonstrated that discs of SiO ₂ ‐CaO _CME /poly(tetrahydrofuran)/poly(caprolactone) hybrids or their dissolution products can drive terminal osteogenic differentiation of human bone marrow stromal cells (h‐BMSCs) in vitro. The current study shows that the 3D‐printed hybrid scaffolds with physiologically relevant 3D architecture further promote h‐BMSC osteogenesis. The 3D‐printed scaffolds support spatially organized cell behavior in an environment mirroring conditions relevant to off‐the‐shelf implant applications. Primary cellular functions, including viability, adhesion, and proliferation, were maintained across 3D scaffold surfaces and within inter‐strut regions. osteogenic commitment was evidenced by the upregulation of lineage‐specific transcripts, hydroxyapatite deposition, and the organized assembly of extracellular matrix (ECM) proteins. Our results demonstrate that 3D‐printed scaffolds drive osteogenesis by modulating cell metabolism, inducing osteogenic morphological transitions, and promoting the expression of osteocalcin and collagen type I alpha 1 chain, alongside hydroxyapatite matrix mineralization. Collectively, our findings highlight the SiO ₂ ‐CaO _CME /poly(tetrahydrofuran)/poly(caprolactone) scaffold's strong osteogenic properties—driven by composition, surface architecture, and ion release – and its promise for clinical bone regeneration.

This study evaluated the use of silica/poly(tetrahydrofuran)/poly(ε-caprolactone) (SiO₂/PTHF/PCL-diCOOH) 3D-printed scaffolds, with channel sizes of either 200 (SC-200) or 500 (SC-500) µm, as biomaterials to support the chondrogenesis of sheep bone marrow stem cells (oBMSC), under in vitro conditions. The objective was to validate the potential use of SiO₂/PTHF/PCL-diCOOH for prospective in vivo ovine studies. The behaviour of oBMSC, with and without the use of exogenous growth factors, on SiO₂/PTHF/PCL-diCOOH scaffolds was investigated by analysing cell attachment, viability, proliferation, morphology, expression of chondrogenic genes (RT-qPCR), deposition of aggrecan, collagen II, and collagen I (immunohistochemistry), and quantification of sulphated glycosaminoglycans (GAGs). The results showed that all the scaffolds supported cell attachment and proliferation with upregulation of chondrogenic markers and the deposition of a cartilage extracellular matrix (collagen II and aggrecan). Notably, SC-200 showed superior performance in terms of cartilage gene expression. These findings demonstrated that SiO₂/PTHF/PCL-diCOOH with 200 µm pore size are optimal for promoting chondrogenic differentiation of oBMSC, even without the use of growth factors.

Osteochondral injuries are increasingly prevalent, yet success in articular cartilage regeneration remains elusive, necessitating the development of new surgical interventions and novel medical devices. As part of device development, animal models are an important milestone in illustrating functionality of novel implants. Inspection of the tissue-biomaterial system is vital to understand and predict load-sharing capacity, fixation mechanics and micromotion, none of which are directly captured by traditional post-mortem techniques. This study aims to characterize the localised mechanics of an ex vivo ovine osteochondral tissue–biomaterial system extracted following six weeks in vivo testing, utilising laboratory micro-computed tomography, in situ loading and digital volume correlation. Herein, the full-field displacement and strain distributions were visualised across the interface of the system components, including newly formed tissue. The results from this exploratory study suggest that implant micromotion in respect to the surrounding tissue could be visualised in 3D across multiple loading steps. The methodology provides a non-destructive means to assess device performance holistically, informing device design to improve osteochondral regeneration strategies.

Regenerative medicine solutions require thoughtful design to elicit the intended biological response. This includes the biomechanical stimulus to generate an appropriate strain in the scaffold and surrounding tissue to drive cell lineage to the desired tissue. To provide appropriate strain on a local level, new generations of scaffolds often involve anisotropic spatially graded mechanical properties that cannot be characterised with traditional materials testing equipment. Volumetric examination is possible with three-dimensional (3D) imaging, in situ loading and digital volume correlation (DVC). Micro-CT and DVC were utilised in this study on two sizes of 3D-printed inorganic/organic hybrid scaffolds (n = 2 and n = 4) with a repeating homogenous structure intended for cartilage regeneration. Deformation was observed with a spatial resolution of under 200 µm whilst maintaining displacement random errors of 0.97 µm, strain systematic errors of 0.17% and strain random errors of 0.031%. Digital image correlation (DIC) provided an analysis of the external surfaces whilst DVC enabled localised strain concentrations to be examined throughout the full 3D volume. Strain values derived using DVC correlated well against manually calculated ground-truth measurements (R² = 0.98, n = 8). The technique ensures the full 3D micro-mechanical environment experienced by cells is intimately considered, enabling future studies to further examine scaffold designs for regenerative medicine.