Decellularized Nail Bed Mediated Osteogenesis And Related Mechanisms

OBJECTIVESConstructing engineered bioscaffolds with good osteogenic property for bone defect repair is a major problem faced by orthopedic clinicians and researchers.In the digit tip regeneration,nail bed is of the essence.However,the detailed mechanism is not quite clear.The purpose of this study aims to explore the structural characteristics and protein composition related to bone regeneration in the nail bed,to design and construct a biological scaffold based on human nail bed,and to study its role and related mechanism of bone defect repair in order to provide new thoughts and strategies for clinical treatment for bone defects.METHODSThe clinically discarded nail bed tissue was collected.First,through histology and high-throughput proteomics analysis,the internal structure and molecular composition of nail bed tissue were analyzed,and the mechanism of osteogenesis mediated by nail bed was illustrated.Secondly,a decellularized nail bed scaffold was prepared by agitation with Triton X-100 and SDS.The bioscaffold was evaluated with histological staining,SEM observation,etc.Subsequently,the cytocompatibility of the decellularized nail bed scaffold and the effect on the osteogenic differentiation of BMSCs were detected.Finally,SD rat critical size calvarial defect model was applied to explore the role of decellularized nail bed scaffold on bone defect repair in vivo.RESULTSThe distal part of nail bed is highly orientated,and the proximal matrix is disordered.The nail bed contains vast vascular structures,and contains substantial osteogenesis-related metal ion regulatory proteins,such as OMD.After decellularization with Triton X-100 and SDS,a decellularized nail bed scaffold was obtained with no cell material remained,and the extracellular matrix structure was kept well.The scaffold contained various growth factors such as EGF and VEGF.Decellularized nail bed scaffolds can promote cell adhesion,migration,proliferation,and promote osteogenic differentiation of BMSCs.When the decellularized nail bed scaffolds implanted in calvarial defect model,a large number of BMP2-positive cells in the grafts were proliferated,and the expression of Runx2 and OCN increased,and more new bone was produced in 2 weeks than decellularized bone matrix(DBM).The new bone mass at 4 and 8 weeks was equivalent to DBM.CONCLUSIONSThe nail bed is rich in vascular structure and a large number of osteogenic related proteins,which lays a foundation for promoting bone regeneration.The human-derived decellularized nail bed scaffold was harvested by agitation method.The cell components were completely removed,the extracellular matrix structure was preserved intact,the micro-structure was not damaged,and various cytokines in the scaffold were preserved to some extent.The scaffold has excellent cytocompatibility,can improve the osteogenic differentiation ability of BMSCs,and can promote bone regeneration in vivo,suggesting its excellent osteoinductive capacity for reconstruction of bone defect.