Effect Of Vegf And Bcp On Wound Healing In Critical Sized Mandibular Defect- In Vitro And In Vivo Studies
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Date
2015-05
Authors
Enezei, Hamid Hammad
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Abstract
One of the most challenging problems in Oral and Maxillofacial Surgery is the repair of critical-sized bone defects in the mandible and craniofacial region that needs a solution. The aim of this study was to produce a clinically applicable model of bone tissue engineering in composite bone graft that has osteoconductive and osteoinductive properties capable of treating critical-sized bone defects in a single step surgical procedure in the rabbit's mandible, beginning with in vitro molecular phase and followed by in vivo clinical phase. Part I and II in vitro phase was conducted to evaluate the effectiveness and the potential influence of VEGF-added-BCP on both angiogenic and osteogenic gene expressions of endothelial cells (ECS) and dental stem cells (DSCs) treated with BCP extract with and without addition of VEGF respectively. The results provided critical insights into the use of BCP granules with and without addition of VEGF which is important for in vitro test before evaluating the efficacy in vivo. This was followed by performing reverse transcriptase-PCR (RT-PCR) to amplify the osteogenesis and angiogenesis-regulated genes.
In part III, the in vivo study, the optimal effective concentration of VEGF in bone regeneration was established using Fibrin sealant delivery system. The in vivo clinical phase included a total of 42 male New Zealand White rabbits, aged between 5 and 6 months; giving a total of 84 mandible sides for experiment. The mandible sides were divided into 4 groups subjected to the treatment given and analysis done. 24 rabbits (48 mandible sides) were subjected to micro-CT and histological studies, while 18 rabbits (36 mandible sides) were subjected to molecular studies. 9 untreated mandible sides (designated as A) versus BCP/FS treated mandible sides (designated as B), control treatments comprising n= 9 rabbits; and the experiment group comprising BCP/FS treated mandible sides (designated as C) versus BCP/FS + VEGF treated mandible sides (designated as D). These rabbits were sacrificed at day 14, 30, xx
45, and 60 after surgery for micro-computed tomography and histological analyses. For molecular analysis, same designated treatment groups were used and the rabbits were sacrificed at day 7, 14, and 21 after surgery.
Results in part I and part II in vitro studies showed angiogenesis gene VEGF was highly expressed in ECS and DSCs by VEGF only treatment but showed some changes in combination of VEGF/BCP treatment in both cell lines. Osteogenesis genes; Bone morphogenetic proteins-2 (BMP-2), Alkaline phosphatase (ALP), Osteocalcin (OC) and Osteopontin (OPN) were shown to be positively affected by both BCP and VEGF. The BCP only treatment group induced high expression of early regulating osteogenesis genes (BMP-2 and OPN). Mineralized gene markers (ALP and OC) were however, highly expressed with VEGF/BCP treatment. Besides that, osteogenesis genes (BMP-2 and OPN) for DSCs were shown to be positively affected by both BCP only and VEGF only groups and slightly effected in VEGF/BCP group. Some genes were expressed at an earlier time interval compared to the other genes depending on the type of treatment. BCP only treatment induced high expression of initial-regulated osteogenesis genes (BMP-2 and OPN).
Results in part III study shows micro-computed tomography images at week 8 after surgery demonstrating complete resorption of BCP granules and young bone formation in group D implanted with VEGF/BCP compared with other groups of study (p<0.05).
Histological and histomorphometrical findings at week 8 after surgery (group D) showed
marked new bone formation. Group D showed up-regulation of VEGF gene expression at
week 1. Osteogenesis markers in group D showed higher expression than other groups at early
stage of bone healing.
The results suggest that the use of BCP/FS composite bone graft loaded with VEGF is ideal for local controlled release of VEGF resulting in accelerated bone formation and healing process of mandibular critical-sized bone defects and this may contribute to the scope of modern reconstructive surgery.
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Oral and Maxillofacial Surgery , that needs a solution.