Human amniotic fluid-derived and dental pulp-derived stem cells seeded into collagen scaffold repair critical-size bone defects promoting vascularization.

INTRODUCTION: The main aim of this study is to evaluate potential human stem cells, such as dental pulp stem cells (DPSC) and amniotic fluid stem cells (AFSC), combined with collagen scaffold, to reconstruct critical size cranial bone defects in animal model. METHODS: We performed two symmetric full-thickness cranial defects on each parietal region of rats and we replenished them with collagen scaffolds with or without stem cells already seeded into and addressed towards osteogenic lineage in vitro. After 4 and 8 weeks cranial tissue samples were taken for histological and immunofluorescence analysis. RESULTS: We observed a new bone formation in all the samples but the most relevant difference in defect correction were shown by stem cell-collagen samples at 4 weeks after implant, suggesting a faster regeneration ability of the combined constructs. The presence of human cells in the newly-formed bone was confirmed by confocal analysis with an antibody directed to a human mitochondrial protein. Furthermore, human cells were found to be an essential part of new vessel formation in the scaffold. CONCLUSIONS: All these data confirmed the strong potential of bioengineered constructs of stem cell-collagen scaffold for correcting large cranial defects in animal model and highlighting the role of stem cells in neo vascularization during skeletal defect reconstruction.