FIBER DIAMETER-DRIVEN MODULATION OF CELL BEHAVIOR IN DECM-ENRICHED ELECTROSPUN SCAFFOLDS FOR BONE TISSUE ENGINEERING

Effective regeneration of large bone defects remains a major clinical challenge, as current bone graft substitutes often result in peripheral mineralization without uniform tissue regeneration across the defect. While mechanical requirements can be addressed through appropriate material selection and scaffold design, many grafts lack the bioactivity needed for consistent and robust bone formation. This study presents a strategy to enhance graft bioactivity using cell-laden extracellular matrix (ECM) as a bioactive component. Our objective is to culture human mesenchymal stem cells (hMSCs) and human umbilical vein endothelial cells (HUVECs) on a nanofiber matrix, then isolate the cell-laden extracellular matrix (ECM) and decellularize it to obtain osteogenic dECM. This study investigates how PCL fiber diameter affects hMSC attachment, proliferation, and osteogenic differentiation for use in dECM collection. PCL fibers in the 200-400 nm range promoted hMSCs proliferation, alkaline phosphatase (ALP) activity, and mineralization under osteoinduction. Due to the hydrophobic nature of PCL, cell sheets detached easily, indicating poor cell-material interaction. To address this, cellulose acetate (CA) was blended with PCL at an 80:20 wt.% ratio to form nanofibers (NF) with optimal diameters. These blended NFs were used to culture hMSCs, HUVECs, or both under osteoinductive conditions for 21 days to harvest cell-laden ECM. After decellularization, three ECM-coated groups were generated: NF+H (HUVECs), NF+M (hMSCs), and NF+Hyb (co-culture). The bioactivity of the cell-laden dECM matrices, particularly NF+Hyb, significantly enhanced the osteogenic activity of cultured hMSCs compared to other groups. This strategy offers a promising approach to boost bone graft bioactivity without relying on exogenous growth factors.