The ability of the body to constantly maintain metabolism homeostasis while fulling the heightened energy and macromolecule demand is crucial to ensure successful tissue healing outcomes. Studies investigating the local metabolic environment during healing are scarce to date. Here, using Type 2 Diabetes (T2D) as a study model, we investigate the impact of metabolism dysregulation on scaffold-guided large-volume bone regeneration. Our study treated wild-type or T2D rats with 5 mm critical-sized femoral defects with 3D-printed polycaprolactone (PCL) scaffolds with 70% porosity. Metabolomics was leveraged for a holistic view of metabolism alteration as healing progress and correlated to regenerated bone tissue volume and quality assessed using micro-computed tomography (µ-CT), histology, and immunohistology. Semi-targeted metabolomics analysis indicated dysregulation in the glycolysis and TCA cycle – the main energy production pathways, in T2D compared to healthy animals. The abundance of metabolites substrates, i.e., amino acids – for protein/ extracellular matrix synthesis was also affected in T2D. Tissue-level metabolites observations aligned with morphological observation with less newly formed bone observed in T2D than wild-type rats. This study enlightens the metabolism landscape during scaffold-guided large-volume bone regeneration in wild-type vs. T2D to further guide the personalization of the scaffold to drive successful regeneration.

Bone regeneration using a scaffold-based tissue engineering approach involves a spectrum of overlapping processes, which are driven by cell-to-cell, cell-to-extracellular matrix (ECM) and cell-to-biomaterials interactions. Traditionally, the study of osteogenesis potential of tissue-engineered constructs (TECs) in vitro only considers the osteoblasts- or mesenchymal cells (MSCs)-to-biomaterials interactions. However, this poorly recapitulates the process of bone regeneration under physiological conditions. In this study, a growth factors free co-culture model, comprising osteoblasts and monocytes was established to allow for the study of the osteogenesis potential of a TEC taking into consideration osteoblasts-to-monocytes and cells-to-biomaterials interactions. Scaffolds made of medical-grade polycaprolactone (mPCL) were fabricated by means of melt electrospinning writing technique. Subsequently, scaffolds were coated with a thin layer of calcium phosphate (CaP) by means of chemical deposition. Scaffolds with CaP coating were seeded with human-derived primary osteoblasts and monocytes and cultured for up to nine weeks. At several time-points, cells were evaluated for alkaline phosphatase and tartrate-resistant acid phosphatase activity. Additionally, cell morphology was observed through fluorescence microscopy and osteoblastic- and osteoclastic-related gene expression was analyzed by quantitative reverse transcription-polymerase chain reaction. The simultaneous presence of osteoblasts and monocytes and CaP accelerated cell matrix formation on scaffolds. Quantitative gene expression profile showed similar findings. Whereby, osteoblastic- and osteoclastic-related gene expression was highest in the PCL/CaP co-culture groups compared to other groups. This indicated synergistic effects of soluble factors secreted by cells and solubilized inorganic components from the scaffolds in promoting matrix deposition.

Aim

A gentamicin-eluting biocomposite consisting of hydroxyapatite (HA) and calcium sulphate (CaS)*1 can provide effective dead space management and bone formation in chronic osteomyelitis. However, radiographic follow-up after implantation of this biomaterial has shown imaging features previously not described with other comparable bone graft substitutes. Last year we presented preliminary results with a follow-up of 6 months. Now we present the radiographic, µCT and histological one-year follow-up of the critical-size bone defect model in sheep. The aim of this study was to simulate the clinical situation in a large animal model to correlate different imaging techniques used in the clinic (Radiography, CT and MRI scans) with histological finding.