Anti-Fibronectin Aptamer Modifies Blood Clot Pattern and Stimulates Osteogenesis: An Ex Vivo Study

Background: Scaffold (SCA) functionalization with aptamers (APT) provides adsorption ofspecific bioactive molecules on biomaterial surfaces. The aim of this study was to observe if SCAenriched with anti-fibronectin APT can favor coagulum (PhC) and osteoblasts (OSB) differentiation.Methods: 20 mu g of APT was functionalized on SCA by simple adsorption. For PhC formation, SCAswere inserted into rat calvaria defects for 17 h. Following proper transportation (buffer solutionPB), OSBs (UMR-106 lineage) were seeded over PhC + SCAs with and without APT. Cells andPhC morphology, PhC cell population, protein labeling and gene expression were observed indifferent time points. Results: The APT induced higher alkaline phosphatase and bone sialoproteinimmunolabeling in OSB. Mesenchymal stem cells, leukocytes and lymphocytes cells were detectedmore in the APT group than when scaffolds were not functionalized. Additionally, an enriched anddense fibrin network and different cell types were observed, with more OSB and white blood cellsin PhC formed on SCA with APT. The gene expression showed higher transforming growth factorbeta 1 (TGF-b1) detection in SCA with APT. Conclusions: The SCA functionalization with fibronectinaptamers may alter key morphological and functional features of blood clot formation, and providesa selective expression of proteins related to osteo differentiation. Additionally, aptamers increaseTGF-b1 gene expression, which is highly associated with improvements in regenerative therapies.