Abstract：
A fundamental question in bone biology concerns the contributions of skeletal stem/progenitor cells (SSCs) in the bone marrow versus the periosteum to bone repair. We found that SSCs in adult bone marrow can be identified based on Leprcre and Adiponectin-cre/creER expression while SSCs in adult periosteum can be identified based on Gli1creERT2 expression. Under steady-state conditions, new bone arose primarily from bone marrow SSCs. After bone injuries, both SSC populations began proliferating but made very different contributions to bone repair. Drill injuries were primarily repaired by LepR+/Adiponectin+ bone marrow SSCs. Conversely, bicortical fractures were primarily repaired by Gli1+ periosteal SSCs, though LepR+/Adiponectin+ bone marrow cells transiently formed trabecular bone at the fracture site. Gli1+ periosteal cells also regenerated LepR+ bone marrow stromal cells that expressed hematopoietic niche factors at fracture sites. Different bone injuries are thus repaired by different SSCs, with periosteal cells regenerating bone and marrow stroma after non-stabilized fractures.
摘要：
骨生物学中的一个基本问题涉及骨髓中的骨骼干/祖细胞（SSC）与骨膜对骨修复的贡献。我们发现，可以根据Leprcre和Adiponectin-cre/creER的表达来鉴定成人骨髓中的SSC，而可以根据Gli1creERT2的表达来鉴定成人骨膜中的SSC。在稳态条件下,新骨主要来自骨髓SSC。骨损伤后,两种SSC种群开始增殖,但对骨修复的贡献却大不相同.钻头损伤主要由LepR+/脂联素+骨髓SSC修复。相反，双皮质骨折主要由Gli1+骨膜SSC修复，尽管LepR/脂联素骨髓细胞在骨折部位短暂形成了小梁骨。Gli1骨膜细胞还再生了LepR骨髓基质细胞，在骨折部位表达造血生态位因子。因此，不同的SSC修复了不同的骨损伤，非稳定型骨折后，骨膜细胞再生骨骼和骨髓基质。
