Immobilization and bioactivity evaluation of FGF-1 and FGF-2 on powdered silicon-doped hydroxyapatite and their scaffolds for bone tissue engineering

Abstract

Fibroblast growth factors (FGFs) are polypeptides that control the proliferation and differentiation of various cell types including osteoblasts. FGFs are also strong inducers of angiogenesis, necessary to obtain oxygen and nutrients during tissue repair. With the aim to incorporate these desirable FGF biological properties into bioceramics for bone repair, silicon substituted hydroxyapatites (Si-HA) were used as materials to immobilize bioactive FGF-1 and FGF-2. Thus, the binding of these growth factors to powdered Si-HA and Si-HA scaffolds was carried out efficiently in the present study and both FGFs maintained its biological activity on osteoblasts after its immobilization. The improvement of cell adhesion and proliferation onto Si-HA scaffolds suggests the potential utility of these FGF/scaffolds for bone tissue engineering.

Effects of nanocrystalline hydroxyapatites on macrophage polarization

“…20 This effect has been also observed with cultured L929 fibroblasts, Saos-2 osteoblasts and MC3T3-E1 preosteoblasts. 14,21 On the other hand, nano-SiHA disks delayed the osteoclast differentiation and decreased the resorptive activity of these cells on their surface, as compared to nano-HA samples, without affecting cell viability, 22 thus indicating a beneficial action of Si-substituted material for bone regeneration in agreement with other studies. 13,15,17,23,24 Since the balance between proinflammatory (M1) and reparative (M2) macrophages has been involved in their negative or positive role in disease and tissue remodelling, 4,5,8,9 the effects of nano-HA and nano-SiHA on murine macrophage populations have been evaluated in the present study in basal conditions and in the presence of either pro-inflammatory (LPS) or anti-inflammatory (IL-10) stimuli.…”

Nanocrystalline silicon substituted hydroxyapatite effects on osteoclast differentiation and resorptive activity

“…This effect has been previously observed using cultured L929 fibroblasts, Saos-2 osteoblasts and MC3T3-E1 preosteoblasts. 24,48 Fig. 3 Effect of 1 mg/ml of powdered nano-HA and nano-SiHA on proliferation (A) and intracellular ROS content (B) of RAW-264.7 macrophages after 1 day treatment.…”

Effects of immobilized VEGF on endothelial progenitor cells cultured on silicon substituted and nanocrystalline hydroxyapatites

“…The present study demonstrates that adsorbed VEGF on nanocrystalline and crystalline HAs can exert a local regulation of the cell response in agreement with previous work by others. [4][5][6][7] On the other hand, the effects of the different Si proportions and nanocrystallinity on the proliferation of EPCs when cultured on disks with adsorbed VEGF (2.5 µg) can be observed in Figure 9B. The comparisons between each nanocrystalline and crystalline HA with different Si proportions and with adsorbed VEGF (2.5 µg) show that the cell number was higher on crystalline materials.…”

“…2 Numerous studies evidence that surface immobilized growth factors present enhanced stability and prolonged function, indicating that cell responses can be regulated by material properties and by growth factors at the implant site. [4][5][6][7] Several growth factors are known to be involved in angiogenesis and vascular homeostasis. 8 Among them, vascular endothelial growth factor presumably bound to heparan sulfate proteoglycans.…”