An In vivo Model for Short-Term Evaluation of the Implantation Effects of Biomolecules or Stem Cells in the Dental Pulp

The continuously growing rodent incisor is a widely used model to investigate odontogenesis and mineralized tissue formation. This study focused on evaluating the mouse mandibular incisor as an experimental biological tool for analyzing in vivo the capacity of odontoblast-like progenitors or bioactive molecules to contribute to reparative dentinogenesis. We describe here a surgical procedure allowing direct access to the forming part of the incisor dental pulp Amelogenin peptide A+4 adsorbed on agarose beads, or dental pulp progenitor cells were implanted in the pulp following this procedure. After 10 days A+4 induced the formation of an osteodentin occluding almost the totality of the pulp compartment. Implantation of progenitor cells leads to formation of islets of osteodentin-like structures located centrally in the pulp. These pilot studies validate the incisor as an experimental model to test the capacity of progenitor cells or bioactive molecules to induce the formation of reparative dentin

FasL Modulates Expression of Mmp2 in Osteoblasts

FasL is a well-known actor in the apoptotic pathways but recent reports have pointed to its important novel roles beyond cell death, as observed also for bone cells. This is supported by non-apoptotic appearance of FasL during osteogenesis and by significant bone alterations unrelated to apoptosis in FasL deficient (gld) mice. The molecular mechanism behind this novel role has not yet been revealed. In this report, intramembranous bone, where osteoblasts differentiate directly from mesenchymal precursors without intermediary chondrogenic step, was investigated. Mouse mandibular bone surrounding the first lower molar was used as a model. The stage where a complex set of bone cells (osteoblasts, osteocytes, osteoclasts) is first present during development was selected for an initial examination. Immunohistochemical staining detected FasL in non-apoptotic cells at this stage. Further, FasL deficient vs. wild type samples subjected to osteogenic PCR Array analysis displayed a significantly decreased expression of Mmp2 in gld bone. To examine the possibility of this novel FasL–Mmp2 relationship, intramembranous bone-derived osteoblastic cells (MC3T3-E1) were treated with anti-FasL antibody or rmFasL. Indeed, the FasL neutralization caused a decreased expression of Mmp2 and rmFasL added to the cells resulted in the opposite effect. Since Mmp2-/- mice display age-dependent alterations in the intramembranous bone, early stages of gld mandibular bone were examined and age-dependent phenotype was confirmed also in gld mice. Taken together, the present in vivo and in vitro findings point to a new non-apoptotic function of FasL in bone development associated with Mmp2 expression

Short-term effects of amelogenin gene splice products A+4 and A-4 implanted in the exposed rat molar pulp

In order to study the short-time effects of two bioactive low-molecular amelogenins A+4 and A-4, half-moon cavities were prepared in the mesial aspect of the first maxillary molars, and after pulp exposure, agarose beads alone (controls) or beads soaked in A+4 or A-4 (experimental) were implanted into the pulp. After 1, 3 or 7 days, the rats were killed and the teeth studied by immunohistochemistry. Cell proliferation was studied by PCNA labeling, positive at 3 days, but decreasing at day 7 for A+4, whilst constantly high between 3 and 7 days for A-4. The differentiation toward the osteo/odontoblast lineage shown by RP59 labeling was more apparent for A-4 compared with A+4. Osteopontin-positive cells were alike at days 3 and 7 for A-4. In contrast, for A+4, the weak labeling detected at day 3 became stronger at day 7. Dentin sialoprotein (DSP), an in vivo odontoblast marker, was not detectable until day 7 where a few cells became DSP positive after A-4 stimulation, but not for A+4. These results suggest that A +/- 4 promote the proliferation of some pulp cells. Some of them further differentiate into osteoblast-like progenitors, the effects being more precocious for A-4 (day 3) compared with A+4 (day 7). The present data suggest that A +/- 4 promote early recruitment of osteogenic progenitors, and evidence functional differences between A+4 and A-4

Potency of extinction of albumin and alpha-foetoprotein production in mouse hepatoma-fibroblasts hybrids

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Contrôle de la production d'albumine et d'alpha-foetoprotéine dans des hybrides somatiques dérivés de cellules d'hépatome

Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe

Cellules souches pulpaires et réparation dentinaire

PARIS5-BU Méd.Cochin (751142101) / SudocSudocFranceF

Nucleoside uptake in normal and cystic fibrosis fibroblasts in vitro

Cultured skin fibroblasts derived from unrelated patients with diagnosed cystic fibrosis were compared with those from one normal individual in respect to thymidine and uridine uptake. The results obtained show that the two nucleosides are incorporated at the same rate by the three cell strains. Therefore, it appears that the reported abnormality [6] in nucleoside uptake in cystic fibrosis cells is not a general characteristic of these cells. © 1980.SCOPUS: ar.jinfo:eu-repo/semantics/publishe