Proteomic and in vitro evaluation of Ca‐containing sol‐gel coatings

Background: Bone tissue regeneration around dental implants depend on processes such osteogenesis, coagulation, angiogenesis and inflammation. Protein adsorption onto the screw surface is the first event-taking place after implantation. These proteins can modulate biological processes are carried out afterwards and condition the implant outcome. The role of calcium on bone metabolism and blood coagulation justifies its use in the development of new materials to bioactivate implant surfaces. Aim/Hypothesis: Ca can condition the material-tissue interface, affecting protein deposition and consequent cellular responses. For this reason, this work aims to study, through proteomics, the adsorbed protein patterns onto Ca-doped biomaterials. Materials and Methods: A sol-gel network from MTMOS, GPTMS and TEOS alkoxysilanes was obtained through the sol-gel method. This material was doped with 0.5, 1, 2.5, 5 and 7.5%wt CaCl2 and, then, applied as coating onto Ti discs. Physicochemical parameter as topography, roughness, wettability and the Ca2 + kinetic release were determined. In vitro was assessed with MC3T3-E1 osteoblast and RAW 264.7 macrophage cells. Proteomic assay was conducted by incubating the samples with human serum for 3 h. Attached proteins were eluted with SDS-DTT solution. Finally, elutions were analyzed using LC-MS/MS. Results: The calcium incorporation into the sol-gel increased the coating roughness and decreased their hydrophilicity. In vitro using MC3T3-E1 revealed an overexpression of both osteogenic markers ALP and OPN on Ca-enriched coatings. In parallel, the Ca incorporation supposed an increased expression of anti-inflammatory marker IL10 and a reduction in the release of TNF-α in a dose-dependent manner respect the base material on RAW 264.7. Ca-doped materials displayed a remarkably increase on the attachment of coagulation-related proteins (THRB, ANT3, PROC) and a higher affinity to VTNC and APOE, proteins involved on osteogenic and anti-inflammatory functions. Conclusions and Clinical Implications: The adsorbed protein pattern movements onto biomaterial surfaces with different calcium amounts were identified. A cluster of proteins related to coagulation and osteogenic functions was identified to improve their affinity to Ca-coatings. Additionally, Ca dose-dependent effects on both osteogenic and inflammatory processes were observed in vitro and confirmed by proteomics. Acknowledgements: This work was supported by MINECO [MAT2017-86043-R, RTC-2017-6147]; Generalitat Valenciana [GRISOLIAP/2018/091]; Universitat Jaume I [UJI-B2017-37, Posdoc/2019/28]; Basque Government [IT611-13]; University of the Basque Country [UFI11/56]. Keywords: Hybrid sol-gel, Dental implants, Protein adsorption, Osseointegration, Coagulation