RESUMO
Since lithium (Liâº) plays roles in angiogenesis, the localized and controlled release of Li⺠ions from bioactive glasses (BGs) represents a promising alternative therapy for the regeneration and repair of tissues with a high degree of vascularization. Here, microparticles from a base 45S5 BG composition containing (wt %) 45% SiO2, 24.5% Na2O, 24.5% CaO, and 6% P2O5, in which Na2O was partially substituted by 5% Li2O (45S5.5Li), were obtained. The results demonstrate that human umbilical vein endothelial cells (HUVECs) have greater migratory and proliferative response and ability to form tubules in vitro after stimulation with the ionic dissolution products (IDPs) of the 45S5.5Li BG. The results also show the activation of the canonical Wnt/ß-catenin pathway and the increase in expression of proangiogenic cytokines insulin like growth factor 1 (IGF1) and transforming growth factor beta (TGFß). We conclude that the IDPs of 45S5.5Li BG would act as useful inorganic agents to improve tissue repair and regeneration, ultimately stimulating HUVECs behavior in the absence of exogenous growth factors.
RESUMO
In regenerative medicine of vascularized tissues, there is a great interest in the use of biomaterials that are able to stimulate angiogenesis, a process necessary for rapid revascularization to allow the transport and exchange of oxygen, nutrients, growth factors and cells that take part in tissue repair and/or regeneration. An increasing number of publications have shown that bioactive glasses stimulate angiogenesis. Because it has been established that boron (B) may play a role in angiogenesis, the aim of this study was to assess the in vivo angiogenic effects of the ionic dissolution products that from a bioactive glass (BG) in the 45S5 system doped with 2 wt% B2O3 (45S5.2B). The pro-angiogenic capacity of 45S5.2B BG was assessed on the vasculature of the embryonic quail chorioallantoic membrane (CAM). Ionic dissolution products from 45S5.2B BG increased angiogenesis. This is quantitatively evidenced by the greater expression of integrin αvß3 and higher vascular density in the embryonic quail CAM. The response observed at 2 and 5 days post-treatment was equivalent to that achieved by applying 10 µg mL-1 of basic fibroblast growth factor. These results show that the ionic dissolution products released from the bioactive glass 45S5.2B stimulate angiogenesis in vivo. The effects observed are attributed to the presence the ionic dissolution products, which contained 160 ± 10 µM borate.
RESUMO
As it has been established that boron (B) may perform functions in angiogenesis and osteogenesis, the controlled and localized release of B ions from bioactive glasses (BGs) is expected to provide a promising therapeutic alternative for regenerative medicine of vascularized tissues, such as bone. The aim of this study was to assess the in vitro angiogenic effects of the ionic dissolution products (IDPs) from BGs in the SiO2-CaO-Na2O-P2O5 (45S5) system and of those from 45S5 BG doped with 2 wt% B2O3 (45S5.2B). The results show, for the first time, the IDPs from 45S5.2B BG stimulated human umbilical vein endothelial cell (HUVEC) proliferation and migration that were associated with phosphorylation of extracellular signal-related kinase (ERK) 1/2, focal adhesion kinase (FAK) and p38 protein. It was also shown that IDPs from 45S5.2B BG could enhance in vitro HUVEC tubule formation and secretion of interleukin 6 (IL6) and the basic fibroblast growth factor (bFGF). The effects observed are attributed to the presence of B in the IDPs. These findings are relevant to bone tissue engineering and regeneration because the IDPs from 45S5.2B BG may act as inexpensive inorganic angiogenic agents providing a convenient alternative to the application of conventional angiogenic growth factors.
RESUMO
Angiogenesis is essential for tissue regeneration and repair. A growing body of evidence shows that the use of bioactive glasses (BG) in biomaterial-based tissue engineering (TE) strategies may improve angiogenesis and induce increased vascularization in TE constructs. This work investigated the effect of adding nano-sized BG particles (n-BG) on the angiogenic properties of bovine type I collagen/n-BG composites. Nano-sized (20-30 nm) BG particles of nominally 45S5 Bioglass® composition were used to prepare composite films, which were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The in vivo angiogenic response was evaluated using the quail chorioallantoic membrane (CAM) as an model of angiogenesis. At 24 h post-implantation, 10 wt% n-BG containing collagen films stimulated angiogenesis by increasing by 41 % the number of blood vessels branch points. In contrast, composite films containing 20 wt% n-BG were found to inhibit angiogenesis. This experimental study provides the first evidence that addition of a limited concentration of n-BG (10 wt%) to collagen films induces an early angiogenic response making selected collagen/n-BG composites attractive matrices for tissue engineering and regenerative medicine.
Assuntos
Cerâmica/farmacologia , Colágeno/química , Nanocompostos/química , Neovascularização Fisiológica/efeitos dos fármacos , Animais , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Bovinos , Células Cultivadas , Cerâmica/química , Colágeno/farmacologia , Coturnix/embriologia , Embrião não Mamífero , Vidro/química , Teste de Materiais , Membranas Artificiais , Nanopartículas/química , Tamanho da Partícula , Engenharia Tecidual/instrumentação , Alicerces Teciduais/químicaRESUMO
Few reports are available in the literature on enamel formation under nutritional deficiencies. Thus, we performed a study to determine the effects of boron (B) deficiency on the maturing dental enamel, employing the rat continuously erupting incisor as the experimental model. Male Wistar rats, 21 days old, were used throughout. They were divided into two groups, each containing ten animals: +B (adequate; 3-mg B/kg diet) and -B (boron deficient; 0.07-mg B/kg diet). The animals were maintained on their respective diets for 14 days and then euthanized. The mandibles were resected, fixed, and processed for embedding in paraffin and/or methyl methacrylate. Oriented histological sections of the continuously erupting incisor were obtained at the level of the mesial root of the first molar, allowing access to the maturation zone of the developing enamel. Dietary treatment did not affect food intake and body weight. Histomorphometric evaluation using undecalcified sections showed a reduction in enamel thickness (hypoplasia), whereas microchemical characterization by energy-dispersive X-ray spectrometry did not reveal alterations in enamel mineralization.