Hyaluronic Acid/Bone Substitute Complex Implanted on Chick Embryo Chorioallantoic Membrane Induces Osteoblastic Differentiation and Angiogenesis, but not Inflammation.

Microscopic and molecular events related to alveolar ridge augmentation are less known because of the lack of experimental models and limited molecular markers used to evaluate this process. We propose here the chick embryo chorioallantoic membrane (CAM) as an in vivo model to study the interaction between CAM and bone substitutes (B) combined with hyaluronic acid (BH), saline solution (BHS and BS, respectively), or both, aiming to point out the microscopic and molecular events assessed by Runt-related transcription factor 2 (RUNX 2), osteonectin (SPARC), and Bone Morphogenic Protein 4 (BMP4). The BH complex induced osteoprogenitor and osteoblastic differentiation of CAM mesenchymal cells, certified by the RUNX2 +, BMP4 +, and SPARC + phenotypes capable of bone matrix synthesis and mineralization. A strong angiogenic response without inflammation was detected on microscopic specimens of the BH combination compared with an inflammatory induced angiogenesis for the BS and BHS combinations. A multilayered organization of the BH complex grafted on CAM was detected with a differential expression of RUNX2, BMP4, and SPARC. The BH complex induced CAM mesenchymal cells differentiation through osteoblastic lineage with a sustained angiogenic response not related with inflammation. Thus, bone granules resuspended in hyaluronic acid seem to be the best combination for a proper non-inflammatory response in alveolar ridge augmentation. The CAM model allows us to assess the early events of the bone substitutes⁻mesenchymal cells interaction related to osteoblastic differentiation, an important step in alveolar ridge augmentation.

VEGF/VEGFR2 Axis in Periodontal Disease Progression and Angiogenesis: Basic Approach for a New Therapeutic Strategy.

Periodontal lesions are associated with activation of pathological angiogenesis and a high number of newly-formed blood vessels. Most angiogenic growth factors have been studied in the crevicular fluid or serum, but tissue correlations with vascular density or endothelial proliferation, are very rare, even inexistent. We assessed the VEGF/VEGFR2 axis expression in a multimodal fashion, in both epithelial and stromal compartments, with emphasis to endothelial proliferation and severity of periodontal lesions. Compared to normal gingiva, negative for VEGF/VEGFR2, periodontal lesions had a progressive increase for these markers from low to severe periodontal lesions. The transition from low to moderate periodontal lesions represents the milestone in disease progression and implies an active angiogenesis based on the highest angiogenic parameter variability observed for these lesions. Epithelial vascularization was firstly observed in moderate periodontal lesions and persists during severe periodontal disease. All the parameters used to quantify angiogenesis in periodontal lesions, were significantly increased in severe periodontal lesions dependent on VEGF expression in both the epithelial and stromal compartment. Our results support the use of anti-VEGF/VEGFR2-targeted therapy as adjuvant treatment for severe periodontal lesions.

Mast cells stimulate lymphangiogenesis in the gingiva of patients with periodontal disease.

The presence and distribution of lymphatic vessels and mast cells in the gingiva under normal and pathological conditions have been reported by several studies, but the relationship between them during inflammatory lymphangiogenesis is virtually unknown. The aim of the present study was to investigate the lymphatic microvessel density (LMVD) and mast cell density (MCD) in the gingiva of patients with periodontal disease compared to normal-like gingiva. Gingival punch biopsies from 51 patients with periodontal disease were investigated. MCs and LVs were detected by double-immunohistochemistry, using primary antibodies against mast cell tryptase and D2-40. The inflammatory infiltrate was evaluated on a scale from 0 (absent) to +3 (severe inflammation). MCs and LVs were counted in the same microscopic field for each case at ×200 magnification. We found a significant increase in the number of both MCs and LVs in cases with mild and moderate inflammatory changes, followed by a slight decrease in cases with severe inflammation. We have shown a particular association between MCs and LVs that may support the contribution of MCs to the development of the lymphatic vasculature in inflammatory conditions. MCD correlated with LMVD in all cases with mild and moderate inflammatory changes, but not in cases with severe inflammation. No correlation was found between MCD/LMVD and the density of the inflammatory infiltrate. Our results suggest the potential involvement of MCs in the induction and maintenance of lymphangiogenesis in the gingiva of patients with periodontal disease in the early steps of evolution.