Endogenous dysregulated energy and amino acid metabolism delay scaffold-guided large volume bone regeneration in a diabetic rat model with Leptin receptor deficiency.

Scaffold-guided bone regeneration (SGBR) offers a promising solution for treating large-volume bone defects. However, its efficacy in compromised healing environments, such as those associated with metabolic conditions like Type 2 Diabetes (T2D), remains poorly understood. This study evaluates the potential of 3D-printed polycaprolactone (PCL) scaffolds for large-volume bone regeneration in preclinical models simulating T2D-induced metabolic challenges. Our results reveal that scaffolds alone are insufficient to overcome the metabolic barriers to effective bone regeneration. Metabolomic analysis of regenerating tissue identified significant disruptions in key metabolic pathways involved in energy production and amino acid synthesis in T2D rats compared to controls. Notably, aconitic acid, ornithine, and glycine levels were elevated in non-diabetic conditions, whereas phosphoenolpyruvate was markedly increased under T2D conditions. Secondary harmonic generation (SHG) imaging further demonstrated impaired collagen organization within T2D regenerating tissue, correlating with disrupted collagen synthesis critical for bone matrix formation. In vitro, the exogenous supplementation of alpha-ketoglutarate (α-KG)-a crucial citric acid cycle intermediate-enhanced mineralized tissue formation in human adipose-derived mesenchymal stem cells (hAdMSCs) from T2D donors, achieving levels superior to non-T2D cells. These findings underscore the metabolic underpinnings of impaired bone regeneration in T2D. Optimized 3D printed scaffolds alone do not counterbalance the impaired regeneration in T2D. Here we highlight a therapeutic potential of metabolic supplementation to optimize SGBR outcomes. This study provides a critical foundation for advancing translational research and developing regenerative therapies tailored to high-risk metabolic disease populations. STATEMENT OF SIGNIFICANCE: Scaffold-guided bone regeneration (SGBR) holds great promise for addressing large bone defects, but its efficacy in metabolically challenged conditions like Type 2 Diabetes (T2D) remains limited. This study uses a metabolomics-driven approach to reveal how metabolic dysregulation in T2D, including disruptions in energy and amino acid pathways, impairs collagen organization and extracellular matrix (ECM) formation-critical for successful bone healing. By identifying α-ketoglutarate (α-KG) as a potential supplement to restore metabolic balance, this work offers novel insights into enhancing scaffold performance under compromised conditions. These findings provide a foundation for integrating bioactive compounds into scaffold designs, advancing personalized strategies in regenerative medicine, and addressing a critical gap in bone defect treatment for diabetic patients.