H‐type blood vessels participate in alveolar bone remodeling during murine tooth extraction healing

Objectives We aimed to investigate whether skeletal‐specific H‐type blood vessels exist in alveolar bone and how they function in alveolar bone remodeling. Materials and Methods H‐type vessels with high expression of CD31 and Endomucin (CD31hiEmcnhi) were immunostained in alveolar bone. Abundance and age‐related changes in CD31hiEmcnhi endothelial cells (H‐ECs) were detected by flow cytometry. Osteoprogenitors association with H‐type vessels and bone mass were detected in tooth extraction model of alveolar bone remodeling by immunohistofluorescence and micro‐CT, respectively. Transcription and expression of H‐EC feature genes during in vitro Notch inhibition were measured by RT‐qPCR and immunocytofluorescence. Results We verified that H‐type vessels existed in alveolar bone, the abundance of which was highest at infancy age, then decreased but maintained a constant level during aging. In tooth extraction model, H‐ECs significantly increased with concomitant perivascular accumulation of Runx2+ osteoprogenitors and gradually augmentation of bone mass. Notch inhibition of in vitro cultured H‐ECs resulted in decreased expression levels of Emcn and hes1, but not Pecam1 or Kdr genes, with decreased expression levels of H‐EC numbers, accordingly. Conclusions The present study suggests that H‐type vessels promote osteogenesis during alveolar bone remodeling. Notch signaling pathway regulates expression of Emcn and possibly determines fate and functions of alveolar H‐ECs.