Fogorvosi szemle, 2005 (98. évfolyam, 1-6. szám)

2005-04-01 / 2. szám

67

FOGORVOSI SZEMLE

B. ALLIOT LICHT, G. BLUTEAU, S. LOPEZ-CAZAUX, D. MAGNE, A. SOUEIDAN, G. DACULSI, J. GUICHEUX

INSERM EM 9903, Nantes, France

COULD STRO-1 CONTRIBUTE TO THE IDENTIFICATION OF ODONTOBLAST-LIKE PRECURSORS IN HUMAN DENTAL PULP CULTURE?

Dental pulp is a specific mesenchymal tissue containing progenitor/stem cells cells capable to differentiate into odontoblast-like cells that produce reparative dentine after injury. Today these progenitor/stem cells have not yet been identified. STRO-1 is a cell surface antigen currently used to identify osteogenic precursors in bone marrow stromal cells. In recent works, STRO-1 positive cells from total dental pulp were immunoselected. This cell fraction expresses -smooth muscle actin (SMA), a marker of pericytes, one of the potential candidates of osteo-odontoblastic precursors (1).

We have developed a model of human pulp cells obtained from teeth expiants (cultured in RPMI-1640 with 10% FCS) that contains pericytes (2). In our model, we have observed cells expressing STRO-1 and, interestingly, the number of these cells increase under dexamethasone (Dex) treatment. Dex is a glucocorticoid well known to enhance the representation of cells with osteoprogenitor potential in human bone marrow stromal cells and to induce mineralization in bone and dental pulp cultures. In our model, the inductive potential of Dex was evidenced by decrease of cell proliferation, enhancement of alkaline phosphatase activity, and induction of DSPP, one of the major odontoblastic markers. In addition, Dex inhibits the percentage of SMA-positive cells. Viewed together, our results provide evidence that Dex stimulates odontoblast-like differentiation of human pulp cells probably through commitment of STRO-1 expressing cells. This work contributes to hypothesize involvement of STRO-1 precursors in the formation of reparative dentin after tooth injury.

References: (1) Shi S., Gronthos S. (2003) J Bone Miner Res, 18: 696-704. (2) Alliot-Licht B., Hurtrel D., Grégoire M. (2001) Arch Oral Biol, 46: 221-8. Keywords: STRO-1, precursor, pericyte Acknowledgements: IFRO, COST action B23

■ 98. évf. 2. sz. 2005.

MC MANZANARES-CÉSPEDES; AM BELMONTECALDERÓN; JA GARCÍA-MOLINA; Y GRECOMACHADO; P CARVALHO-LOBATO; M GORETNICAISE *; CM PILIPILI *, A DHEM *

Human Anatomy Unit, Departament of Human Anatomy and Embryology, University of Barcelona, Spain ‘Human Anatomy Research Unit, Catholic University of Louvain, Brussels, Belgium

CALCIFIED TISSUES IN THE CLOSURE OF FRONTAL SUTURE IN RATS

The aim of this study is to evaluate the influence of biomechanical forces on the shape and composition of the calcified tissues of the rat metopic suture. An experiment has been performed, consistent in the surgical isolation of a rectangular fragment of the two frontal bones adjacent to the metopic sruture, witch became thus liberated of mechanical stresses. Following the results of a previous study, all the animals were operated when they were 18 days old, so that the metopic suture will be still open. The samples containing the metopic sutures were divided for their study in three parts. The results were evaluated during the first three weeks after the operation.

Our results show that there is no difference in the sutural form between the operated, sham-operated and the control, non-operated rats. In the same manner, the calcified tissues present in the sutural areas of the animals do not show significant differences between the tree groups. In the rat, the presence of chondroid tissue in the metopic suture is not as evident as in man or in other animals, such as the pig. It takes part, with the other calcified tissues, in the process of sutural closure, but without having the principal role. Afterwards, during the first two weeks after the surgical procedure is progressively reduced in size and substituted by lamellar bone.

We conclude that the form of the sutures and its tissue composition is genetically predetermined, but can be altered by extrinsic conditions, acting in a precise and early stage of growth. Keywords: cranial structures, calcified tissues Acknowledgement: This work has been conducted within the framework of the COST-Action B23.