Marie-Laure Colombier

Accelerated craniofacial bone regeneration through dense collagen gel scaffolds seeded with dental pulp stem cells.

Therapies using mesenchymal stem cell (MSC) seeded scaffolds may be applicable to various fields of regenerative medicine, including craniomaxillofacial surgery. Plastic compression of collagen scaffolds seeded with MSC has been shown to enhance the osteogenic differentiation of MSC as it increases the collagen fibrillary density. The aim of the present study was to evaluate the osteogenic effects of dense collagen gel scaffolds seeded with mesenchymal dental pulp stem cells (DPSC) on bone regeneration in a rat critical-size calvarial defect model. Two symmetrical full-thickness defects were created (5 mm diameter) and filled with either a rat DPSC-containing dense collagen gel scaffold (n = 15), or an acellular scaffold (n = 15). Animals were imaged in vivo by microcomputer tomography (Micro-CT) once a week during 5 weeks, whereas some animals were sacrificed each week for histology and histomorphometry analysis. Bone mineral density and bone micro-architectural parameters were significantly increased when DPSC-seeded scaffolds were used. Histological and histomorphometrical data also revealed significant increases in fibrous connective and mineralized tissue volume when DPSC-seeded scaffolds were used, associated with expression of type I collagen, osteoblast-associated alkaline phosphatase and osteoclastic-related tartrate-resistant acid phosphatase. Results demonstrate the potential of DPSC-loaded-dense collagen gel scaffolds to benefit of bone healing process.

Impact of periodontitis definition in epidemiological research. Results from the EPIPAP study in postpartum women.

The purpose of this investigation was to study the impact of using various definitions of periodontitis on the frequency of periodontitis and on the associations with some known risk factors for periodontitis in a population of postpartum women in France. A clinical examination was performed within 2-4 d postpartum in 932 at-term women at five maternity units. We studied six definitions of periodontitis; five were applicable if at least two teeth were found to have the following: (i) a proximal clinical attachment level (CAL) of ≥ 3 mm; (ii) a probing depth (PD) of ≥ 4 mm; (iii) a PD of ≥ 4 mm and a CAL of ≥ 3 mm at the same site; (iv) a proximal PD of ≥ 5 mm or a proximal CAL of ≥ 4 mm; or (v) a PD of ≥ 4 mm and a CAL ≥ 3 mm and bleeding on probing at the same site. The sixth definition required the involvement of four teeth with a PD of ≥ 4 mm and a CAL of ≥ 3 mm at the same site. Associations between case status according to each definition and maternal characteristics (age, educational level, smoking before pregnancy, and time since last dental visit) were analyzed using generalized estimating equation models. The definition of periodontitis had an impact on the frequency of periodontitis, which ranged from 12.1% to 37.7%, and produced different ORs for the associations with risk factors for periodontitis.

Periodontal reconstruction by heparan sulfate mimetic-based matrix therapy in Porphyromonas gingivalis-infected mice

Background Periodontitis is a set of chronic inflammatory diseases affecting the supporting structures of the teeth, during which a persistent release of lytic enzymes and inflammatory mediators causes a self-perpetuating vicious cycle of tissue destruction and repair. A matrix-based therapy using a heparan sulfate (HS) analogue called ReGeneraTing Agent (RGTA) replaces destroyed HS by binding to available heparin-binding sites of structural molecules, leading to restoration of tissue homeostasis in several inflammatory tissue injuries, including a hamster periodontitis model. Methods The ability of RGTA to restore the periodontium was tested in a model of Porphyromonas gingivalis-infected Balb/cByJ mice. After 12 weeks of disease induction, mice were treated weekly with saline or RGTA (1.5 mg/kg) for 8 weeks. Data were analyzed by histomorphometry. Results RGTA treatment restored macroscopic bone loss. This was related to (1) a significant reduction in gingival inflammation assessed by a decrease in infiltrated connective tissue, particularly in cells expressing interleukin 1ß, an inflammatory mediator selected as a marker of inflammation; (2) a normalization of bone resorption parameters, i.e. number, activation and activity of osteoclasts, and number of preosteoclasts; (3) a powerful bone formation reaction. The Sharpeys fibers of the periodontal ligament recovered their alkaline phosphatase coating. This was obtained while P. gingivalis infection was maintained throughout the treatment period. Conclusions RGTA treatment was able to control the chronic inflammation characteristic of periodontitis and blocked destruction of periodontal structures. It ensured tissue regeneration with recovery of the periodontiums anatomy.