Immunodetection of Osteopontin at Sites of Resorption in the Pulp of Rat Molars

Abstract

(YS,AN) S U M M A R Y Osteopontin (OPN) has been proposed to act as a substrate for osteoclast adhesion during bone resorption. The aim of the present study was to examine the presence and distribution of OPN at sites of resorption in traumatized radicular pulp. The upper first molars of 6-week-old male Sprague-Dawley rats were luxated and then repositioned in the original sockets. The animals were sacrificed by intracardiac perfusion at 10 and 14 days after tooth reimplantation. The teeth were decalcified in EDTA and then processed for embedding in paraffin for histochemistry or LR White resin for immunocytochemistry. Odontoclasts were identified by their multinucleated morphology and expression of tartrate-resistant acid phosphatase (TRAP). Osteopontin was immunolocalized using postembedding colloidal gold labeling with a chicken egg yolk anti-rat OPN antibody. After reimplantation of the teeth, TRAP-positive cells were present along the pulp dentin wall. Osteopontin was not consistently detected at exposed predentin/dentin surfaces. However, gold particles were often found at the margin of resorption lacunae. Labeling was also seen over the Golgi region and cytoplasmic vesicles of odontoclasts and of neutrophils and fibroblast-like cells. The results suggest that accumulation of OPN at the predentin/dentin surface is not a prerequisite for adhesion of odontoclasts to the wall substance and that recruited odontoclasts produce OPN locally to mediate cell and/or matrix events within the resorption lacuna.

Osteopontin Distribution in the Canine Skeleton during Growth and Structural Maturation

“…In our study, no unspecific staining of skeletal muscle or connective tissue occurred either. It has also been shown earlier that the immunoreactivity of bone tissue is not lost after EDTA processing [Mukai et al, 1986]; OPN can even be demonstrated at the ultrastructural level [Shimazu et al, 2002].…”

The static magnetic field accelerates the osteogenic differentiation and mineralization of dental pulp cells

“…Accordingly, we thought that DPCs still had the potential to differentiate into osteoblast-like cells from the limited population of dental progenitors/stem cells, inspite of a possibly lower efficiency of differentiation. On the other hand, bone and dentin are similar in their matrix protein composition, including OPN, collagen type I, and bone sialoprotein, though their crystal structures are different (Batouli et al 2003;Shimazu et al 2002). One of the functions of those matrices seemed to support cell differentiation, whether in the osteogenesis or detinogenesis (Batouli et al 2003).…”

Histochemical and immunocytochemical study of hard tissue formation in dental pulp during the healing process in rat molars after tooth replantation

“…In contrast, physiological root resorption commonly occurs in human deciduous teeth when numerous odontoclasts, which are the same cell type as osteoclasts in their ultrastructural features and functions (Sasaki 2003), gather along the pulpdentin border and extend their cellular processes into the dentinal tubules (Sasaki et al 1988;Sahara et al 1996;Kannari et al 1998;Linsuwanont et al 2002). Similar findings have been observed under the different pathological condition used in the present study and in a previous report, viz., numerous TRAP-positive osteoclast-lineage cells accumulate along the pulp-dentin border after tooth replantation (Shimazu et al 2002). On the other hand, the temporal appearance of dendritic cells along the pulpdentin border has been also reported after tooth injury such as tooth replantation and cavity preparation (Shimizu et al 2000;Ohshima et al 2003;Nakakura-Ohshima et al 2003).…”