Our immunohistochemistry study shows invasion of gingival epithelial cells, fibroblasts, alveolar bone lining osteoblasts, and embedded osteocytes by P. gingivalis at the infected sites 3 days after multiple oral inoculations.
Investigation of osteocalcin mRNA revealed an expression pattern similar to col1a, with staining of cells in the osteogenous areas and in bone lining osteoblasts and apical surfaces of the trabeculae.
Five-μm longitudinal sections were stained either by hematoxylin and eosin (H&E) for counting the number of cuboidal and plump bone lining osteoblasts, or by tartrate-resistant acid phosphatase (TRAP) assay kit (Sigma-Aldrich, St . Louis MO, USA) for counting the number of TRAP-positive multinucleated osteoclasts within the secondary spongiosa.
The aberrant bone formation correlated with increased numbers of tartrate resistant acid phosphatase positive osteoclasts and decreased numbers of bone lining osteoblasts in 4 week old Osx:EfnB1−/− mice, compared to Osx Cre control mice.
After 3 w of reambulation, trabecular bone of RA+VIB mice had a 30% greater bone volume fraction, 51% greater marrow osteoprogenitor population, 83% greater osteoblast surfaces, 59% greater bone formation rates, and a 235% greater ratio of bone lining osteoblasts to marrow adipocytes than RA mice.
Moreover, col1a signal was identified in the bone lining osteoblast cells situated at the lateral surfaces of the trabeculae and along the rims of the vertebral bodies.
Quiescent HSCs reside preferentially at the endosteal region where bone-lining osteoblasts and their secreted proteins are critical components of HSC niches.
However, there is significant debate about the more detailed location of HSCs within the marrow, which contains both the endosteal region close to the bone lining osteoblasts (OBs; endosteal niche) and a vascular niche located around small sinusoidal blood vessels associated with various stromal and neuronal elements.
Immunohistofluorescence on fixed bone sections confirmed TIMP-3 expression in bone lining osteoblasts, endothelial cells as well as in megakaryocytes (Figure 2C).
However, osteoblast lineage cells that are found within the subendosteal niche include osteoprogenitor cells, quiescent bone lining cells, and active osteoblasts [11], [24].
We focus our report on gene expression in chondrocytes at the growth plate, osteocytes, endosteum and trabecular lining osteoblasts and in bone marrow cells.
