Calcification capacity of dental papilla mesenchymal cells transplanted in the isogenic mouse spleen

Abstract

The capacity of the dental pulp to form calcified tissue was examined in papilla cells dissociated from first molar tooth germs of the neonatal mouse and isografted in the spleen for up to 7 days. To obtain papilla cell populations without odontoblasts, pulpal mesenchyme was isolated mechanically from the enamel organ after 0.1% trypsin treatment and rolled on a membrane filter. On day 3 after transplantation, the grafted papilla cells had changed into large, spindle-shaped cells, and initial calcification with needle-like crystals began in association with the collagenous matrix surrounding those cells. On day 7 after transplantation, the spindle cells transformed into odontoblast-like cells containing well-developed secretory organelles, and irregular, but nontubular, calcified tissues were commonly observed surrounding the extracellular collagenous matrix. The calcified tissue matrix with cellular inclusions displayed a structure similar to that of osteodentin. During this period, an intense positive reaction for alkaline phosphatase (ALPase) activity was demonstrated along the cell membranes of the odontoblast-like cells aligned at the periphery of forming calcified tissue. Enzymatic activity could not be detected on the cells incorporated completely into osteodentin-like matrix. The present results show that the papilla cell population transplanted into the spleen formed osteodentin-like material, thus demonstrating the capacity of papilla cells to produce calcified tissue.

Postnatal human dental pulp stem cells (DPSCs) in vitro and in vivo

“…The potential of developing dental cells to generate a dentinlike tissue has previously been described after transplantation of neonatal rodent and bovine dental papilla cells (33)(34)(35). However, in another earlier study, intact human dental pulp from a premolar tooth of a 13-year-old male failed to generate a dentin matrix and͞or odontoblast-like cells when transplanted beneath the kidney capsule of athymic mice (36).…”

Endochondral calcification by hypertrophic chondrocytes in the Meckel's cartilage grafted into the isogenic mouse spleen.

“…The same specimens, after obtaining ultrathin sections, were decalcified en bloc with Plank-Rychlo solution (PLANK and RYCHLO,1952) for 2 h according to our previous report (ISHIZEKI et al, 1990) for electron microscopy.…”

Transforming Growth Factor-ß1 (TGF-ß1) immunoreactivity in heterotopic grafts of adult dental apical papilla.

“…In an attempt to avoid the possible deleterious effects of the reaction of the host in the transplant, the strategy of performing heterotopic transplants of matrix dentin proteins 19 , embryonic tissue 16,20 and stem cells previously isolated and amplified in culture in isogenic or immunosuppressed animals has been used from the beginning 1 .…”

“…Dentinogenesis was always obtained in these conditions 1,16,18,20 ; however, it is not yet clearly elucidated how stable this dentin is with time. Our data demonstrate 16 cells in the transplant developed reactive tertiary or osteoid dentin occupying the entire transplant during the first week after transplantation and it was finally eliminated.…”

“…Our data demonstrate 16 cells in the transplant developed reactive tertiary or osteoid dentin occupying the entire transplant during the first week after transplantation and it was finally eliminated. This type of dentin is characterized by the loss of its tubular structure and the acquisition of a morphology similar to the bone has been described in various clinical and experimental conditions 21,22 , among them the trasplants 10,16,20 , and its appearance has been justified as the result of a reaction to exogenous factors, among which is the inflammatory reaction of the host 16 .…”