Oral Presentations O.616 Effect of BMSCs on the critical size defect of rat mandible A. Sarac, H. Koca, I. Tuglu, F.O. Kurt, A. Kazanc. Ege University School of Dentistry Dep. of Oral Surgery, Izmir, Turkey Purpose: Cultured bone marrow stromal cells (BMSCs) can be regarded as a mesenchymal progenitor/precursor cell population derived from adult stem cells. We used autologous BMSC/biomaterial and hydroxyapatite gel (HAG) to treat mandibular critical size defects (CSD). The aim of our study was to investigate the effect of autologous BMSC/biomaterials in the repair of CSD and the relation with NOS and apoptosis during this process. Method: Critical size defects with 4 mm in diameter (control group) were created in the left mandibular bodies of forty male Wistar rats. The defects were ﬁlled with BMSC suspension (group 1), osteoblastic differentiated BMSC (odBMSC) suspension (group 2), BMSC on the HAG (group 3), odBMSC on the HAG (group 4) or only HAG (group 5). Animals were sacriﬁed after 8 weeks and specimens were processed for histology, immunocytochemistry and morphometry. Apoptosis was analyzed by the Terminal deoxynucleotidyl transferase-mediated dUTP Nick-End Labeling (TUNEL) method. Results: Morphometry of new bone formation, osteoid production, ﬁbrous tissue ingrowth and cellular activity were superior in odBMSC on the HAG group. NOS expression was related to apoptotic response of the cells. Higher NOS produced more apoptosis and vice versa. Conclusion: Our results are very promising for the use of cultureexpanded BMSC in the repair of CSD. Especially odBMSC with HAG scaffold was more effective in stimulating new bone and osteoid development in our study. The expression of NOS isoforms during the healing is temporal and related to the apoptosis. These mechanisms may have clinical applications to improve life quality of the patients. O.617 Effect of bone resorption in iliac graft on rabbit calvarium H. Park, H.-S. Hong, K.-D. Park, B.-S. Kim, J.-R. Jang, M.S. Kook, H.-K. Oh. Department of Oral and Maxillofacial Surgery, Chonnam natioinal university hospital, Gwangju, Republic of Korea This research was performed to study histological change and difference of absorption rate with or without periosteum when auto-grafting the tame rabbit’s block bone of ilium to cranium. Block bone (size 8(L)*8(W)*5(H) mm) was grafted from left and right iliac crests of 21 tame rabbits. The test group included the periosteum while the control group did not. Each graft was transplanted and ﬁxed to ipsilateral frontal bone. After 1, 4, 8 weeks, we compared absorption rate and histological change of grafted bone and periosteum. 1. Absorption rate of grafted block bones was statistically analyzed using X-ray radiography and height of screw heads. We did not ﬁnd any signiﬁcant difference between test group and control group of 1-week and 4-week cases. But in the 8-week cases, there was signiﬁcant decrease in the absorption rate. 2. Histological analysis revealed that block bones grafted with periosteum united with adjacent connective tissue from the upper part and vascularized successfully. Block bones without periosteum showed inﬁltration of inﬂammatory cells in the neighboring connective tissues. Based on our research, when clinically performing auto-graft on the defectivesite of alveolar bone, we expect to decrease bone absorption rate and to expedite restoration by grafting block bones with periosteum.
Tissue engineering and cell therapy I
O.618 Engineered full thickness oral mucosa model P. Pascal1 , P. Pierrillas2 , C. Auxenfans3 , B. Kinikoglu3 , P. Breton2 , P. Bouletreau2 , O. Damour3 . 1 Centre Hospitalier Lyon Sud, Pierre Benite, France; 2 Service de Stomatologie, Chirurgie Maxillo-Faciale et Plastique de la Face, Centre Hospitalier Lyon-Sud – Hospices Civils de Lyon, France; 3 Banque de Tissus et Cellules, France Objective: To develop, optimize and characterize a 3D Engineered oral mucosa equivalent made of an epithelium layer on a Lamina Propria Equivalent (LPE), as both autologous splitthickness skin and oral mucosa grafts used to cover oral defects result in donor site morbidity. Methods: The technology used to reconstruct the 3D oral mucosa model was the same as the one previously developed for the reconstruction of a 3D skin equivalent model (Balk et al; 2006). Fibroblasts and keratinocytes were isolated from gingival mucosa biopsies obtained from healthy patients. After ampliﬁcation, the ﬁbroblasts were seeded and cultured on a Collagenglycosaminoglycan-Chitosan scaffold during 3 weeks giving rise to a LPE. Then, keratinocytes were seeded at the top of the LPE and cultured for 3 additional weeks. Results: Histologic analysis showed that after 9 weeks of culture a pluristratiﬁed and differentiated epithelium was present on the LPE. In the LPE, the ﬁbroblasts migrated, proliferated and synthesized extracellular matrix that we characterized by immunohistochemy and Transmission Electronic Microscopy. Conclusions: Thanks to the presence of the LPE, we can hope that the graft will limit the wound contracture observed with standard epithelial sheets. Due to the presence of living ﬁbroblasts, keratinocytes are nourished through the Growth Factors synthesized by the former, till the neovasculature develops. LPE makes the engineered tissue resistant and easier to handle. Preclinical trials are planned. O.619 How does nicotine affect bone regeneration? L. Ma, L.W. Zheng, L.K. Cheung. OMFS, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China Objective: To study the effect of nicotine on bone regeneration and neo-angiogenesis using a rabbit model of madibular lengthening and evaluate the inﬂuence of nicotine on the expression of osteogenesis and angiogenesis related growth factors in distraction regenerate. Methods: 50 adult New Zealand white rabbits were randomly assigned to two equal groups: placebo control and 1.5g nicotine. 60-day time release nicotine pellets or placebo pellets were implanted in the neck subcutaneous tissue of the rabbits. Total nicotine exposure time was seven weeks. After nicotine implantation, a standard procedure of mandibular body osteotomy and distraction were performed. The animals were sacriﬁced at day 5 of distraction, day 1, week 1, week 2 and week 4 of consolidation. The madibles were harvested for the analysis of plain X-ray, micro-CT, Histological staining and real-time PCR. Results: Nicotine exposure increased microvessel density, whereas inhibited blood ﬂow and bone formation. Frequent appearance of cartilage islands suggested ischemia and low oxygen tension in the distraction regenerate. The expression of bone morphogenetic protein was decreased. The expression of vascular endothelial growth factor was increased. Conclusions: Nicotine compromises bone regeneration by causing ischemia and directly inhibitory effect on osteoblastic cells. Nicotine exposure enhances angiogenesis but can not compensate for the adverse effect of vasoconstriction.