Biomedical subjects

Dominique Lauzier

Publications and source records attributed to Dominique Lauzier.

6 recordsLinked to original sources

PubMed2006

Early injection of OP-1 during distraction osteogenesis accelerates new bone formation in rabbits.

Distraction osteogenesis (DO) is a surgical technique for generating new bone by applying controlled distraction of two bony segments post osteotomy. A limitation of the technique is the long time required for the new bone to consolidate. We investigated the effect of injecting osteogenic protein 1 (OP-1) at the beginning of distraction in a rabbit model of DO. Regenerate bone was evaluated using radiology, densitometry, micro-computed tomography (microCT) and histomorphometry. Immunohistochemsitry was used to evaluate changes in expression of various ligands, growth factors and receptors following OP-1 treatment. Compared to the control, a two-fold increase in bone volume was apparent for treated groups at 3 weeks post injection. An upregulation of almost all of the 41 genes examined was observed. Results suggested that applying OP-1 early during distraction can accelerate bone formation by the activation of numerous pathways. This study provides further insights on strategies to improve bone regeneration rate in DO.

Animals↗

PubMed2005

Immunohistochemical localization of bone morphogenetic protein-signaling Smads during long-bone distraction osteogenesis.

In this study we investigated the expression of bone morphogenetic protein (BMP)-signaling Smads in distraction osteogenesis (DO). Osteotomy of the right tibia was performed in 14 skeletally mature white New Zealand male rabbits. Lengthening was started 1 week later at a rate of 0.5 mm/12 hr and was maintained for 3 weeks. Expression of Smad proteins 1, 4, 5, 6, 7, and 8 and Smad ubiquitin regulatory factors (Smurfs) 1 and 2 was evaluated in the distracted zone using immunohistochemistry. Expression of receptor-regulated Smads (R-Smads) 1, 5, and 8 showed a significant increase during the distraction phase, followed by a gradual decrease during the consolidation phase. Smad 4 showed significant expression during both distraction and the beginning of the consolidation phase. Smad 6 and Smad 7 were highly expressed during the consolidation phase. Staining for both Smurfs 1 and 2 was maximal at the end of the distraction period. Staining for all proteins was most intense in chondrocyte and fibroblast-like cells. Expression pattern of R-Smads correlated with our previously reported expression pattern of BMPs 2, 4, and 7 and their receptors. These results therefore suggest a role for the whole BMP signaling pathway including the Smad proteins in DO.

Animals↗

PubMed2005

Local delivery of 17beta-estradiol improves reendothelialization and decreases inflammation after coronary stenting in a porcine model.

In the current study, we investigated the effect of local intravascular delivery of 17beta-estradiol (17beta-E) on subsequent in-stent neointimal hyperplasia. Twenty-seven stents were implanted in coronary arteries of juvenile swine. Coronary arteries were randomized to local treatment with 17beta-E or no drug therapy (control-vehicle treated). Twenty-eight days post-treatment, angiographic images revealed an improved minimal lumen diameter (2.2 +/- 0.2 vs. 1.3 +/- 0.2 mm, P < 0.005) and a reduction of late lumen loss (1.7 +/- 0.2 vs. 2.3 +/- 0.1 mm, P < 0.01) in 17beta-E-treated vessels compared to control-vehicle treated. Histological analyses showed a reduction of stenosis (51.49 +/- 6.75 vs. 70.86 +/- 6.24%, P < 0.05), mean neointimal thickness (0.51 +/- 0.07 vs. 0.83 +/- 0.14 mm, P < 0.05) and inflammation score (1.29 +/- 0.28 vs. 2.85 +/- 0.40, P < 0.05) in 17beta-E-treated arteries compared to control-vehicle treated arteries. Immunohistochemistry analyses revealed a reduction of proliferating smooth muscle cells and increased in-stent reendothelialization in 17beta-E-treated arteries. Finally, we observed a correlation between neointimal hyperplasia and inflammation score, which in turn, was inversely related to reendothelialization. Locally delivered, 17beta-E is inhibiting the inflammatory response and smooth muscle cells proliferation and improving vascular reendothelialization which together are contributing to reduce in-stent restenosis in a porcine coronary injury model. Together, these data demonstrate the potential clinical application of 17beta-estradiol to improve vascular healing and prevent in-stent restenosis.

Angioplasty, Balloon, Coronary↗

PubMed2003

Effects of osteogenic protein-1 on distraction osteogenesis in rabbits.

In this study we tested the effect of locally applied osteogenic protein 1 (OP-1) on distraction osteogenesis in rabbits. Seven days after tibial osteotomy, distraction was started at a rate of 0.25 mm per 12 h for 3 weeks. At the end of the distraction period, OP-1 was injected at the site of osteotomy. Four different dosages were tested (0, 80, 800, or 2000 microg; eight rabbits per dose group). Rabbits were sacrificed 3 weeks later, and histologic, densitometric, and biomechanical parameters were assessed. No significant differences were found between groups for any parameter. To explain why this approach was only modestly successful, the expression of BMP receptor protein in the newly formed tissue was analyzed by immunohistochemistry. Strong expression of BMP receptor IA, IB, and II was found during the early distraction phase, but not during later stages of the process. Thus, it appears that the lack of receptor protein in the target tissue impairs the effect of OP-1 given at the end of the distraction period. Possibly, OP-1 could be more useful when applied early in the distraction phase.

Animals↗

PubMed2003

Expression of bone morphogenetic proteins during mandibular distraction osteogenesis.

Distraction osteogenesis is a form of in vivo tissue engineering in which the gradual separation of cut bone edges results in the generation of new bone. In this study, the temporal and spatial expression of bone morphogenetic proteins (BMPs) 2, 4, and 7 was examined in a rabbit model of mandibular distraction osteogenesis. Fourteen skeletally mature male rabbits were studied. After osteotomy, a distractor was applied to one side of the mandible. After 1 week of latency, distraction was initiated at 0.25 mm every 12 hours for 3 weeks (distraction period), followed by a 3-week consolidation period. Two animals were killed each week after surgery. The generate bone was analyzed for the expression of BMP-2, -4, and -7 by using standard bone histological and immunohistochemical techniques. BMP-2 and -4 were highly expressed in osteoblastic cells during the distraction period and in chondrocytes during the consolidation period. BMP-7 demonstrated relatively minor expression in osteoblastic cells during the distraction period. All BMPs were strongly expressed in vascularized connective tissue during the distraction period. These data indicate that BMPs participate in the translation of mechanical stimuli into a biological response during mandibular distraction osteogenesis.

Animals↗

PubMed2003

Serial bone densitometry during mandibular distraction osteogenesis.

The purpose of this study was to obtain serial measurements of bone mineral density (BMD) of the mandible during distraction osteogenesis. Fourteen skeletally mature male rabbits were subjected to unilateral mandibular osteodistraction at a defined rate. Two animals were sacrificed each week after surgery for 7 wk. The mandible and overlying soft tissue were resected and the BMD measured using dual-energy X-ray absorptiometry (DXA). Measurements obtained from the generate bone were compared to the contralateral (control) hemi-mandible. In the control hemi-mandible, BMD remained stable throughout the distraction protocol at 0.5 gm/cm2. In the distracted hemi-mandible, BMD sharply decreased to 0.35 gm/cm2 by the second week of distraction but steadily increased starting the third week of distraction. BMD surpassed control levels by wk 7. BMD measurements may provide a noninvasive assessment of bone mineralization and strength during distraction osteogenesis.

Absorptiometry, Photon↗