Capacity of Dental Pulp Differentiation in Mouse Molars as Demonstrated by Allogenic Tooth Transplantation

Abstract

Dental pulp elaborates both bone and dentin under pathological conditions such as tooth replantation/transplantation. This study aims to clarify the capability of dental pulp to elaborate bone tissue in addition to dentin by allogenic tooth transplantation using immunohistochemistry and histochemistry. After extraction of the molars of 3-week-old mice, the roots and pulp floor were resected and immediately allografted into the sublingual region in a littermate. In addition, we studied the contribution of donor and host cells to the regenerated pulp tissue using a combination of allogenic tooth transplantation and lacZ transgenic ROSA26 mice. On Days 5-7, tubular dentin formation started next to the preexisting dentin at the pulp horn where nestin-positive odontoblast-like cells were arranged. Until Day 14, bone-like tissue formation occurred in the pulp chamber, where intense tartrate-resistant acid phosphatase-positive cells appeared. Furthermore, allogenic transplantation using ROSA26 mice clearly showed that both donor and host cells differentiated into osteoblast-like cells with the assistance of osteoclast-lineage cells, whereas newly differentiated odontoblasts were exclusively derived from donor cells. These results suggest that the odontoblast and osteoblast lineage cells reside in the dental pulp and that both donor and host cells contribute to bone-like tissue formation in the regenerated pulp tissue.

The Expression of GM-CSF and Osteopontin in Immunocompetent Cells Precedes the Odontoblast Differentiation Following Allogenic Tooth Transplantation in Mice

“…The summarized pulpal changes in the transplanted teeth were as follows (see the previous report by Takamori et al 2008): All odontoblasts showed the degenerative features and inflammatory reactions, including numerous neutrophils, fibrin networks, and a hemorrhage that occurred in the pulp chamber on day 1; cell proliferation in the pulp chamber became most active on day 3; nestin-positive and OPN-negative newly differentiated odontoblast-like cells were arranged along the pulp-dentin border to deposit the dentin matrix in the pulp horn on days 5 to 7; and bone-like tissue occurred in the pulp chamber apart from the continuous deposition of the dentin matrix on day 14.…”

Differentiation capacity of BrdU label-retaining dental pulp cells during pulpal healing following allogenic transplantation in mice

“…Cell division and cell death also play an important role in regulating the reorganization of dental pulp during the healing process following tooth injuries (6,7,9,21). Recent studies using the same experimental model as that in this study have shown that cell proliferation precedes the odontoblast differentiation (13,19). However, there are no available data on the relationship between LRCs and proliferative or apoptotic cells during pulpal healing following allogenic tooth crown transplantation.…”

“…Thus, the experimental model for tooth replantation or transplantation is not suitable for the investigation of mechanisms regulating the odontoblast differentiation, because the reparative dentinogenesis is not always concomitant with pulpal healing. In contrast, transplantation of the tooth crown into the sublingual region is a useful experimental model for analyzing the differentiation processes of both odontoblasts and osteoblasts, because deposition of the dentin matrix consistently occurs beneath the preexisting dentin and the bone tissue is induced apart from the dentin matrix (13,16,19). Allogenic tooth crown transplantation using lacZ transgenic ROSA26 mice has shown that both donor and host mesenchymal cells differentiate into osteoblast-like cells, whereas newly differentiated odontoblast-like cells are exclusively derived from donor pulpal cells (19).…”

“…In contrast, transplantation of the tooth crown into the sublingual region is a useful experimental model for analyzing the differentiation processes of both odontoblasts and osteoblasts, because deposition of the dentin matrix consistently occurs beneath the preexisting dentin and the bone tissue is induced apart from the dentin matrix (13,16,19). Allogenic tooth crown transplantation using lacZ transgenic ROSA26 mice has shown that both donor and host mesenchymal cells differentiate into osteoblast-like cells, whereas newly differentiated odontoblast-like cells are exclusively derived from donor pulpal cells (19). These findings indicate that proper pulpal cells interact with the other cells migrating from surrounding tissues or bone marrow during pulpal healing after operation.…”

Tooth autotransplantations - lessons from animal models: a review

“…The disadvantage is that autotransplantation does not generate a new tooth but just fills in the gap in a more exposed part of the dental arch. To search for other options, stem cellbased tissue engineering (Ohazama et al 2004), allotransplantations or even xenotransplantations have been tested using animal models (Groisman et al 1989;Schwartz et al 1990;Schwartz and Andreasen 2002b;Kim et al 2006;Takamori et al 2008;Mutoh et al 2011;Saito et al, 2011).…”