Promote Osteogenesis in Tissue Engineered Bone by Pre-seeding Endothelial Progenitor Cells-derived Endothelial Cells

Introductions Tissue-engineered bone regeneration requires not only a cell population capable of creating new bone and a biocompatible scaffold, but also the formation of an appropriate vascular bed to support the metabolic needs of bone tissue. Slow ingrowth of blood vessels can lead to cell loss through hypoxic cell death during the early post-implantation stage. To overcome the obstacle of nutrient and oxygen transport to a 3dimentional tissue-engineered bone, a vascular network must be established throughout the newly-formed bone. Bone marrow-derived endothelial progenitor cells (EPCs), a population of cells with high proliferative potential, can differentiate into endothelial lineage cells in vitro and promote neovascularization in animal models of ischemia. To test the hypothesis that addition of EPCs-derived endothelial cells (ECs) may improve osteogenesis and prevent necrosis of tissue engineered bone through efficient neovascularization, we pre-seeded EPCs-derived ECs on polycaprolactone-hydroxyapatite (PCL-HA) scaffold followed by seeding with marrow stromal cells (MSCs)-derived osteoblasts, and implanted to repair a mouse femoral defect.