The role of CCR2+ cells in alveolar bone repair of mice: histomorphometric and molecular assessment

Abstract

Bone is a mineralized connective tissue, which shares a variety of regulatory molecules with the immune system, such as different cytokines and chemokines. However, the mechanisms involved in the interaction between skeletal and immune system, in the bone repair, process are not yet completely understood. Previous studies have shown that monocytes/macrophages perform an important role in tissue repair process. They are present even in the bone repair process, possibly acting in the immune/inflammatory initial phase, and in the transition between granulation tissue removal and the osteogenesis process. In this context, receptors responsible for the migration of monocytes can control the influx of these cells to bone repair sites, influencing significantly the repair process. Among the chemokine receptors involved in monocyte/macrophages chemoattraction, CCR2 receptor has a relevant role, and acts directing the migration of cells such as chemokines front of CCL2 (MCP-1). Previous results from our group showed (by RealTimePCR) the expression of CCR2 receptor and its CCL2 ligand through the process of post-extraction alveolar repair in mice (results from: FAPESP Regular Grant 2010/15755-9 and FAPESP Doctoral Scholarship 2009/11496-1). However, the real role of CCR2 receptor in this process remains unknown. Thus, the objective of this project is to elucidate the role of chemokine receptor CCR2 in alveolar repair process in mice by histomorphometric and molecular assessment. C57Bl/6 (WT) and CCR2KO (genetically deficient in the receptor CCR2) lineage will be used. Following the extraction of the right upper incisor, the maxilla containing the remaining dental alveolus will be collected at 0, 7, 14 and 21 days; then, the samples will be submitted to molecular and histological processing. Qualitative and quantitative assessment will be performed in a optical microscopic to verify the proportion of tissue occupied by clot fibers, fibroblasts, blood vessels, inflammatory cells, bone matrix, osteoblast and osteoclast. As well the molecular analysis by RealTimePCR for quantification of CBFA1/RUNX2 , OCN, ALP, RANKL, OPG, COL-I and VEGF expression. Then, the resulting data will be statistically analyzed and compared between both strains and different time points. The joint analysis of these data certainly will contribute to improve the understanding of the alveolar bone repair process, promoting specific knowledge that can cooperate significantly to the development of new strategies for diagnosis, prevention and therapy of bone diseases.