title: Osteoblast precursors, but not mature osteoblasts, move into developing and fractured bones along with invading blood vessels.
abstract: During endochondral bone development, the first osteoblasts differentiate in the perichondrium surrounding avascular cartilaginous rudiments; the source of trabecular osteoblasts inside the later bone is, however, unknown. Here, we generated tamoxifen-inducible transgenic mice bred to Rosa26R-LacZ reporter mice to follow the fates of stage-selective subsets of osteoblast lineage cells. Pulse-chase studies showed that osterix-expressing osteoblast precursors, labeled in the perichondrium prior to vascular invasion of the cartilage, give rise to trabecular osteoblasts, osteocytes, and stromal cells inside the developing bone. Throughout the translocation, some precursors were found to intimately associate with invading blood vessels, in pericyte-like fashion. A similar coinvasion occurs during endochondral healing of bone fractures. In contrast, perichondrial mature osteoblasts did not exhibit perivascular localization and remained in the outer cortex of developing bones. These findings reveal the specific involvement of immature osteoblast precursors in the coupled vascular and osteogenic transformation essential to endochondral bone development and repair.
authors: Massachusetts General Hospital and Harvard Medical School, Boston, 02114, USA.
authors: Christa
authors: C
authors: Maes
authors: Tatsuya
authors: T
authors: Kobayashi
authors: Martin K
authors: MK
authors: Selig
authors: Sophie
authors: S
authors: Torrekens
authors: Sanford I
authors: SI
authors: Roth
authors: Susan
authors: S
authors: Mackem
authors: Geert
authors: G
authors: Carmeliet
authors: Henry M
authors: HM
authors: Kronenberg
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D001808:Blood Vessels / Q000166:cytology / Q000378:metabolism*; D001846:Bone Development / Q000502:physiology*; D001861:Bone Regeneration / Q000502:physiology*; D001842:Bone and Bones / Q000098:blood supply / Q000473:pathology / Q000502:physiology; D019070:Cell Lineage; D002465:Cell Movement; D019902:Chondrocytes / Q000166:cytology / Q000502:physiology; D004622:Embryo, Mammalian / Q000033:anatomy & histology / Q000502:physiology; D005260:Female; D050723:Fractures, Bone; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D010006:Osteoblasts / Q000166:cytology / Q000502:physiology*; D020286:Pericytes / Q000378:metabolism; D011247:Pregnancy; D013234:Stem Cells / Q000166:cytology / Q000502:physiology*
chemical_list: D015415:Biomarkers