Biodegradable and biocompatible materials are the basis for tissue engineering. As an initial step for developing vascular grafts, the in vitro biocompatibility of poly(e-caprolactone) (PCL), recently suggested for several clinical applications, was evaluated in this study using L929 mouse fibroblasts. Different cellular aspects were analyzed in order to know the cell viability during cell culture on PCL films: adhesion, proliferation, morphology, LDH release and mitochondrial function. Since topography and other surface characteristics of materials play an essential part in cell adhesion, PCL membranes with either smooth or rough surface were prepared, characterized and used to carry out cell cultures. During short culture times, PCL produced a significant stimulation of mitochondrial activity evaluated by reduction of the MTT reagent. The results provide evidences of good adhesion, growth, viability, morphology and mitochondrial activity of cells on PCL films. Therefore, it can be concluded that PCL is a suitable and biocompatible material as a scaffold for vascular graft development. r

Biphasic calcium phosphate (BCP), a mixture of hydroxyapatite (HA) and b-tricalcium phosphate (b-TCP), has attracted attention as an excellent bone graft substitute. Mixtures of ceramics with agarose, as natural biodegradable binder, have been recently performed in order to increase the flexibility of the ceramic component and to facilitate the biomaterial preparation. In previous studies we have evaluated the response of both L929 fibroblasts and Saos-2 osteoblasts to hydroxyapatite-bTCP/agarose disks observing a higher sensitivity of osteoblasts to this biomaterial. In the present study, the use of specific fluorescent probes and antibodies has allowed to evaluate different cell function parameters as biocompatibility markers for the cell/biomaterial interaction of Saos-2 osteoblasts cultured for 7 days on hydroxyapatite-bTCP/agarose disks. The cell cycle subG 1 fraction, the exposition of phosphatidylserine on the outside surface of the plasma membrane and the analysis of plasma membrane integrity versus cell size, indicate that the interaction with the biomaterial induces a light increase of apoptosis in osteoblasts without producing cell necrosis. The high percentage of viable cells on the biomaterial and the preservation of endothelial nitric oxide synthase (eNOS) expression, eNOS activity and mitochondrial membrane potential (Dj m ), demonstrate the good biocompatibility of hydroxyapatite-bTCP/agarose disks and its potential utility for bone substitution and repair.

Poly(-caprolactone) (PCL) is considered as a potential substrate for wide medical applications. In previous studies we carried out the in vitro biocompatibility assessment of PCL films using L929 mouse fibroblasts, obtaining good cell behaviour but a transitory stimulation of mitochondrial activity and cell retraction. Reactive oxygen species (ROS), mainly formed in mitochondria, can impair the function of several cellular components and produce cell oxidative stress by changing the normal red-ox status of the major cell antioxidants as glutathione. The aim of this study was to measure intracellular ROS production and glutathione content of L929 fibroblasts cultured on PCL films. Cell size, internal complexity, cell cycle and lactate dehydrogenase release were also evaluated. The films were treated with NaOH before culture to improve the cell-polymer interaction. PCL induces a transitory but significant oxidative stress in L929 fibroblasts. The treatment of PCL films with NaOH reduces this effect. PCL also induces transitory changes on cell size and complexity. Nevertheless, after 7 days in culture, cells reach control levels for all the studied parameters. Neither cell cycle nor membrane integrity appears affected by this oxidative stress respect to control cells at any culture time. These results underline the cytocompatibility of PCL films and, therefore, its potential utility as a suitable scaffold in tissue engineering. r

Crystalline nanoparticles are very attractive building blocks for the preparation of nanostructured materials. These particles can be dispersed in different noncrystalline mesostructured matrixes in order to obtain nanocomposite systems which combine the properties of both components broadening their functionality. In the present study, a novel nanocomposite bioceramic formed by nanocrystalline apatite particles uniformly embedded into a mesostructured SiO 2 −CaO−P 2 O 5 glass wall has been synthesized through the evaporation-induced self-assembly (EISA) method, commonly used for mesoporous bioactive glass synthesis, but accelerating the sol−gel apatite crystallization rate by strong acidification. Moreover, the use of F127 surfactant as a structure directing agent in this synthesis has allowed the homogeneous nanocrystalline apatite particles incorporation inside of the amorphous mesoporous glass. In vitro bioactive assays have shown a fast apatite-like phase formation similar to that exhibited by mesoporous bioactive glasses. Furthermore, the response of L929 fibroblasts and Saos-2 osteoblasts to this new nanocomposite has indicated a significant improvement in its biocompatibility compared with conventional mesoporous bioactive glasses.

Three dimensional interconnected macroporous (pore diameter: 600-800 lm) hydroxyapatite/agarose disks have been evaluated in this study as potential bone regeneration scaffolds. With this purpose, the adhesion and proliferation of human Saos-2 osteoblasts on this biomaterial were analyzed.

The haemocompatibility of NaOH-treated poly(ε-caprolactone) (PCL) has been evaluated in vitro by analysing several parameters, including plasma recalcification time, whole blood clotting time and platelet adhesion/activation. NaOH-treated PCL films showed a significant decrease in the clot formation speed and a reduced number of adhered platelets, which mainly exhibited nonactivated morphologies. Furthermore, mature endothelial cells derived from peripheral endothelial progenitor cells were cultured on the polymer to investigate the effects of the endothelial lining on polymer haemocompatibility. Interestingly, cells cultured on NaOH-treated PCL films showed a significant stimulation of NO production. Although further research is required, NaOH treatment could be an interesting and simple strategy to modify PCL-based materials in order to enhance endothelial NO production, where compromised, and provide a better interaction of the scaffold with the blood components. In conclusion, these results reinforce the use of NaOH-treated PCL as a haemocompatible polymer for vascular tissue-engineering applications.

Biodegradable and biocompatible materials are the basis for tissue engineering. As an initial step for developing vascular grafts, the in vitro biocompatibility of poly(e-caprolactone) (PCL), recently suggested for several clinical applications, was evaluated in this study using L929 mouse fibroblasts. Different cellular aspects were analyzed in order to know the cell viability during cell culture on PCL films: adhesion, proliferation, morphology, LDH release and mitochondrial function. Since topography and other surface characteristics of materials play an essential part in cell adhesion, PCL membranes with either smooth or rough surface were prepared, characterized and used to carry out cell cultures. During short culture times, PCL produced a significant stimulation of mitochondrial activity evaluated by reduction of the MTT reagent. The results provide evidences of good adhesion, growth, viability, morphology and mitochondrial activity of cells on PCL films. Therefore, it can be concluded that PCL is a suitable and biocompatible material as a scaffold for vascular graft development. r