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Anti-Inflammatory Cytokines in Peri-Implant Soft Tissues: A Preliminary Study on Humans Using CDNA Microarray Technology

The mucosa around implants and the gingiva around teeth respond to plaque formation with the development of an inflammatory lesion which has similar magnitude and histological features. Different cell types in inflamed and healthy periodontal and peri-implant tissues are capable of producing a variety of important pro-inflammatory and anti-inflammatory cytokines and growth factors which mediate the host response. The aim of this study is to compare the expression levels of anti-inflammatory cytokines detectable in the peri-implant soft tissue of two single-implant crowns supported either by zirconia or titanium abutments. Two frozen samples of peri-implant soft tissue of two single-implant crowns supported either by zirconia or titanium abutments were treated to obtain mRNA. The mRNA extracted from these specimens was converted in cDNA and analyzed with “SuperArray GEArray Q Series Human Inflammatory Cytokine/Receptor Gene Array kit”, planned for studying 96 genes involved in inflammatory response. Data showed that gene expression levels of anti-inflammatory cytokines were higher in specimens sampled from the zirconia abutment compared with those from the titanium abutment. It was considered important to detect the mRNA levels of the anti-inflammatory mediators in healthy peri-implant tissues to verify the biological tolerability of zirconia compared with titanium abutments. The difference detected in cytokine expression could be due to the intrinsic biological tolerability of zirconia ceramics or to a lesser bacterial accumulation.

Raloxifene covalently bonded to titanium implants by interfacing with (3-aminopropyl)-triethoxysilane affects osteoblast-like cell gene expression

Since Raloxifene, a drug used in osteoporosis therapy, inhibits the osteoclast functions but not osteoblast functions, it could improve the recovery during implant surgery. This preliminary report describes a simple method to link, through a covalent bond, Raloxifene to titanium by interfacing with (3-aminopropyl)-Triethoxysilane as assessed by the IR-FT and SEM. To evaluate the biological response of osteoblast-like cells to this implant, we compared expression gene profiling of cell cultures on Raloxifene conjugated implant and normal implant by DNA microarray. By using DNA microarrays containing 19,200 genes, we identified differently expressed genes in osteoblast-like cell line (MG-63). Surface Raloxifene conjugated implants have been shown to have a relevant importance in modifying cell response. This result could be an interesting starting point for the use of an immediate functional loading of implants.

Novel hydroxyapatite biomaterial covalently linked to raloxifene

Since raloxifene, a drug used in osteoporosis therapy, inhibits osteoclast, but not osteoblast functions, it has been suggested to improve recovery during implant surgery. The present paper describes an effective method to link raloxifene, through a covalent bond, to a nano-Hydroxyapatite-based biomaterial by interfacing with (3-aminopropyl)-Triethoxysilane as assessed by Infra Red-Fourier Transformed (IR-FT) spectroscopy and Scanning Electron Microscope (SEM). To evaluate the safety of this modified new material, the vitality of osteoblast-like cells cultured with the new biomaterial was then investigated. Raloxifene-conjugated HA-biomaterial has been shown to be a safe material easy to obtain which could be an interesting starting point for the use of a new functional biomaterial suitable in bone regeneration procedures.

MG63 AND MC3T3-E1 OSTEOBLASTIC CELL LINES RESPONSE TO RALOXIFENE

Bone resorption in edentulous regions often results in inadequate ridge for implant osseointegration. In order to overcome this problem, the use of osteoconductive biomaterials has been proposed as a carrier for different types of pharmacological molecules. Since raloxifene, a drug used in osteoporosis therapy, inhibits the osteoclast, but not osteoblast functions, it has been suggested to improve recovery during implant surgery. The present work evaluated in vitro the effect of raloxifene on two different cell populations: the human osteoblast-like cells (MG63) and osteoblasts derived from rat calvaria (MC3T3-E1). The morpho-functional investigations carried out showed a different behavior of the two cell lines. Raloxifene showed a stimulatory effect towards MG63 cell proliferation with a significant increase in cell viability after 7 days of culture. On the contrary, MC3T3-E1 cells showed a significant reduction in cell viability, when compared with the same cells at 72 h, or with the control cell population. The predominantly proliferative effect of raloxifene on MG63 cells is partly confirmed by the reduction of alkaline phosphatase activity, an early marker of osteoblast differentiation. The different effect of raloxifene on osteoblastic population in relationship to the type and age of the cell is an issue that needs further investigation.