Cell Biology International ISSN 1065-6995 doi: 10.1002/cbin.10908 RESEARCH ARTICLE In vitro treatment with concentrated growth factors (CGF) and sodium orthosilicate positively affects cell renewal in three different human cell lines Veronica Bonazza 1 , Elisa Borsani 1,2 , Barbara Buffoli 1,2 , Silvia Parolini 3 , Francesco Inchingolo 4 , Rita Rezzani 1,2 and Luigi Fabrizio Rodella 1,2 * 1 Division of Anatomy and Physiopathology, Department of Clinical and Experimental Sciences, University of Brescia, V.le Europa 11, Brescia 25123, Italy 2 Interdipartimental University Center of Research “Adaption and Regeneration of Tissues and Organs—(ARTO)”, University of Brescia, Brescia 25123, Italy 3 Department of Molecular and Translational Medicine, University of Brescia, Brescia 25123, Italy 4 Department of Interdisciplinary Medicine, University of Bari “Aldo Moro”, Bari 70121, Italy Abstract The aim of this study was to investigate the in vitro effect of Silicon, in the soluble form of sodium orthosilicate, combined and not with the concentrated growth factors (CGF), a platelet-rich preparation, on three different human cell lines of fibroblasts (NHDF), endothelial cells (HUVEC), and osteoblasts (HOBs). Each cell type was treated with sodium orthosilicate at the final concentration of 0.5 mM and 1 mM, CGF, and sodium orthosilicate combined with CGF, for 72 h. At the end of the experimental period, the in vitro effect on cell growth, proliferation, and metabolic activity was evaluated by performing a simple cell count, using an automated cell counter and by evaluating the expression of the intracellular proliferation marker Ki-67, using Fluorescence-activated cell sorting (FACS) analysis. Moreover, the expression of other cell markers and active molecules, such as Collagen type I, Osteopontin, Vascular Endothelial Growth Factor, and endothelial Nitric Oxide Synthase, was evaluated, through immunohistochemistry. Results obtained showed that the combined use of CGF and sodium orthosilicate stimulates cell growth, proliferation, and metabolic activity, suggesting that this treatment could be effective in tissue regeneration. Keywords: CGF; flow cytometry; growth factors; platelets; sodium orthosilicate; tissue engineering Introduction Regeneration is a regulative developmental process, ubiqui- tous across all species. It functions throughout the life cycle to maintain or restore the normal form and function of cells, tissues and, in some cases, organs, appendages, and whole organisms. It is a complex process of healing and tissue growth, which involves different biological elements and strategies, such as the use of bone grafts (Garc  ıa-Gareta et al., 2015), biomaterials, growth factors, natural or synthetic scaffolds (Loh and Choong, 2013; Asti and Gioglio, 2014) and the use of autologous cells, in particular stem cells (Manunta et al., 2016; Joo et al., 2017). Recently, the use of platelet-rich preparations such as platelet-rich plasma (PRP), platelet-rich fibrin (PRF), platelet rich in growth factors (PRGF), and concentrated growth factors (CGF) has been shown to be effective in promoting the natural processes of wound healing and tissue regeneration (Ramos-Torrecillas et al., 2014; Sermer et al., 2015; Badran et al., 2017). These concentrates are obtained from the patient’s own blood and contain autologous platelets, growth factors, and cytokines involved in the key processes  Corresponding author: e-mail: luigi.rodella@unibs.it Abbreviations: BC, buffy coat; BMPs, bone morphogenetic proteins; CGF, concentrated growth factors; Col I, collagen type I; EGF, epidermal growth factor; EGM, endothelial growth medium; eNOS, endothelial nitric oxide synthase; FGF, fibroblast growth factor; FGM, fibroblast growth medium; HOBs, human osteoblasts; HUVEC, human umbilical vein endothelial cells; IGF, insulin-like growth factor; Na 4 SiO 4 , sodium orthosilicate; NHDF, normal human dermal fibroblasts; OGM, osteoblast growth medium; OPN, osteopontin; OSA, orthosilicic acid; PDGF, platelet-derived growth factor; PPP, platelet poor plasma; PRGF, platelet-rich in growth factors; PRF, platelet-rich fibrin; PRP, platelet-rich plasma; RBC, red blood cells; RP, red part; Si, silicon; SiO 2 , silica; TGF-b, transforming growth factor b; VEGF, vascular endothelial growth factor; WP, white part 353 Cell Biol Int 42 (2018) 353–364 © 2017 International Federation for Cell Biology