Evaluation of changes at maxillary sutural region in rats caused by vegf applied with nano particle carriers following rapid maxillary expansion

The aim of the study was to evaluate the bone remodelling effects of vascular epithelial growth factor (VEGF) applied through gold nano-particle (AuNP) carriers at the maxillary sutural region of rats after experimental maxillary expansion by histomorphometric analysis. In this study, a total of 30 Wistar rats that were 14 week old, 250 g weight were divided in 5 groups. Their maxillas were expanded transversally by expansion appliance with helixes that were bended from 0.014 inch diameter stainless steel arch wire. Chemical solution with gold nano particles and vascular endothelial growth factor was prepared in laboratuary conditions and at the 5th day of expansion they were injected between central teeth to the palatinal submucosal region of rats. In the experiment there are 5 groups to which palatal expansion done. In this 5 groups, different chemical solutions as isotonic saline, AuNP, VEGF, AuNP-VEGF mixture and AuNP+Oligonucleotide+VEGF were injected. 10 days after injection rats were sacrificed. At the end of the experiment, maxillas of rats were dissected and histological sections were prepared for histomorphometric evaluation. Stained sections were analysed using Sterioinvestigator 7.0.5 program. For volumetric measurements Leica C Plan X10 objektive (NA = 0.22) was used. In the study, soft tissue, hard tissue and total volumes were evaluated in groups to which isotonic saline (control), AuNP, VEGF, AuNP+VEGF and AuNP+Oligonucleotide+VEGF were injected. Homogenity of variances were examined with Levene test (p= 0.216, p<0.05). Homogeneous distributed groups were compared with ANOVA test and Tukey test was used for paired comparisons. In the histological evaluation of the study when total bone volume that includes soft and hard tissue volumes was considered, a statistically significant increase was seen in VEGF group compared to AuNP+VEGF group (p<0.05, p=0.028). Likewise, a similar statistically significant increase was recorded when soft tissue volume and total volume were considered, again in VEGF group when it was compared to AuNP group (p<0.05, p=0.046), (p<0.05, p=0.046). When soft tissue volume was considered, a statistically significant increase was seen in VEGF group compared to AuNP+Oligonucleotide+VEGF group (p<0.05, p=0.046). Results of the study revealed that even though VEGF accelerates bone remodelling, the use of AuNPs for VEGF transfer into the cell with the method of this study, do not increase bone remodelling. It was also found that VEGF had an important role in soft tissue development.