New injectable two-step forming hydrogel for delivery of bioactive substances in tissue regeneration

The authors would like to thank Dr Alberto Fernández-Medarde (Instituto de Biología Molecular y Celular del Cáncer, Centro de Investigación del Cáncer, CSIC-USAL) for proofreading the article. Moreover, the help and the advice in the interpretation on FTIR spectra given by Dr Jose Adrián Gavin (Organic Chemistry Department, ULL) and Dr Antonio Manuel Hernández-Daranas (Instituto de Productos Naturales y Agrobiología, CSIC) is appreciated.A hydrogel based on chitosan, collagen, hydroxypropyl-γ-cyclodextrin and polyethylene glycol was developed and characterized. The incorporation of nano-hydroxyapatite and pre-encapsulated hydrophobic/hydrophilic model drugs diminished the porosity of hydrogel from 81.62 ± 2.25% to 69.98 ± 3.07%. Interactions between components of hydrogel, demonstrated by FTIR spectroscopy and rheology, generated a network that was able to trap bioactive components and delay the burst delivery. The thixotropic behavior of hydrogel provided adaptability to facilitate its implantation in a minimally invasive way. Release profiles from microspheres included or not in hydrogel revealed a two-phase behavior with a burst- and a controlled-release period. The same release rate for microspheres included or not in the hydrogel in the controlled-release period demonstrated that mass transfer process was controlled by internal diffusion. Effective diffusion coefficients, Deff, that describe internal diffusion inside microspheres, and mass transfer coefficients, h, i.e. the contribution of hydrogel to mass transfer, were determined using ‘genetic algorithms’, obtaining values between 2.64·10−15 and 6.67·10−15 m2/s for Deff and 8.50·10−10 to 3.04·10−9 m/s for h. The proposed model fits experimental data, obtaining an R2-value ranged between 95.41 and 98.87%. In vitro culture of mesenchymal stem cells in hydrogel showed no manifestations of intolerance or toxicity, observing an intense proliferation of the cells after 7 days, being most of the scaffold surface occupied by living cells.This work was supported by the Ministry of Science and Technology, Spain (MAT2014-55657-R)

Cartilage repair by local delivery of transforming growth factor-β1 or bone morphogenetic protein-2 from a novel, segmented polyurethane/polylactic- co-glycolic bilayered scaffold

This study aimed to analyze the in vitro and in vivo release kinetics and evaluate the grades of repair induced by either the release of 50 ng of transforming growth factor-β1 or 2.5 or 5 μg of bone morphogenetic protein-2 (BMP-2) from a bilayer scaffold of segmented polyurethane/polylactic- co-glycolic (SPU/PLGA) in osteochondral defects, in a rabbit model. The scaffold consisted of a porous, bone-directed PLGA layer, overlaid with a cartilage-directed layer of growth factor (GF)-loaded PLGA microspheres, dispersed in a matrix of SPU. The PLGA porous layer was fabricated by gas foaming. Microspheres were prepared by a double emulsion method. SPU was synthesized by following the two-step method. GF release kinetics were assessed using iodinated (125I) GFs. The in vivo release profiles of both GFs fitted to zero-order kinetics, demonstrating a consistently good control of their release rates by SPU. Cartilage-like tissue, characterized by histological analysis, scoring, and immunolabeling of chondrogenic differentiation markers, was observed only after 12 weeks, maintaining integrity up to at least 24 weeks, independently of the GF and the dose of BMP-2. The biocompatibility and the resulting good quality, hyaline repair cartilage convert this system into a promising candidate for future applications in osteochondral lesions. © 2013 Wiley Periodicals, Inc.Peer Reviewe

Fate of nanostructured lipid carriers (NLCs) following the oral route: design, pharmacokinetics and biodistribution

The aim of this study was to develop a nanostructured lipid carriers (NLC) formulation containing spironolactone (SPN-NLCs), and to investigate its potential for the oral delivery of poorly water-soluble compounds. SPN-NLCs were orally administered to rabbits and the pharmacokinetics of spironolactone and its metabolites was evaluated. As reference formulation, we administered syrup. Spironolactone was only detected in a few plasma samples; hence, metabolite levels were employed for the pharmacokinetic analysis. The absolute bioavailability of 7α-TMS was significantly higher with the syrup than those obtained with the SPN-NLCs (0.7 versus 0.4, p < 0.05). However, no significant differences were observed in the bioavailability of canrenone, revealing a different canrenone/7α-TMS ratio depending on the administered formulation. Orally administered (99m)Tc-radiolabeled SPN-NLCs were mainly detected in the small intestine. These results suggest the retention of the nanocarriers in the underlying epithelium and further uptake by the epithelial cells

Osteoprotective effect of the marine alkaloid norzoanthamine on an osteoporosis model in ovariectomized rat

Norzoanthamine (NZ), an alkaloid that has been isolated from the marine cnidiaria Zoanthus sp., has been shown an interesting anti-osteoporotic activity. Although its mechanism of action is not yet clear, it seems that it is different from those of currently used drugs making it particularly interesting. Previous studies have been carried out mostly in vitro. Herein, we present an in vivo study that allows to check the real potential of NZ as a protector substance by direct application into ovariectomized rat bone using a sustained delivery system. Histological and histomorphometric results in ovariectomized rats showed higher bone quality as a result of greater number of trabeculae and osteogenic activity in the group implanted with NZ, compared to controls. In contrast with the untreated controls, NZ-treated groups showed a balanced osteoblast/osteoclast number ratio, similar to that found in the normal bone. These results suggest that NZ could be useful as adjunct to other osteoporosis treatments, but probably its main therapeutic role would be as preventive therapy against bone deterioration.This research was funded by research grants ProID2017010113 from Gobierno de Canarias, PID2019-109476RB-C21 (BIOALGRI) from Ministerio de Ciencia y Tecnología, MAC2/4.6d/249 from European Union, OSTEONOR from Fundaci ́on CajaCanarias. P.G.G. acknowledges the University of La Laguna for her fellowship grant (M-ULL). Authors acknowledge the use of LC-MS equipment at the ULL general research facilities. The manuscript was edited by Guido Jones, currently funded by the Cabildo de Tenerife, under the TFinnova Programme supported by MEDI and FDCAN funds.Peer reviewe

Development of PLGA-mannosamine nanoparticles as oral protein carriers

Here we report the development of polymeric nanoparticles, made of poly(lactide-co-glycolide) (PLGA) chemically modified with mannosamine (MN), intended to specifically interact with the intestinal mucosa and facilitate the intestinal transport of proteins. PLGA-MN nanoparticles displayed nanometric size and a negative zeta potential, which was lower than that of the PLGA nanoparticles. This correlate well with the preferential location of the MN group on the nanoparticles surface obtained by X-ray photoelectron spectroscope (XPS). The presence of MN groups in the polymer chain led to a different surface morphology noted by SEM, an increase of the encapsulation of model proteins, and to help stabilizing the nanoparticles in simulated intestinal fluids. Furthermore, the MN modification significantly enhanced the nanoparticle's interaction with the epithelial cells in human intestinal follicle-associated epithelium cell culture model. Overall, the MN modification significantly modifies the properties of PLGA nanoparticles making them more suitable as nanocarriers for oral protein delivery

The Bone Regeneration Capacity of BMP-2 + MMP-10 Loaded Scaffolds Depends on the Tissue Status

Biomaterials-mediated bone formation in osteoporosis (OP) is challenging as it requires tissue growth promotion and adequate mineralization. Based on our previous findings, the development of scaffolds combining bone morphogenetic protein 2 (BMP-2) and matrix metalloproteinase 10 (MMP-10) shows promise for OP management. To test our hypothesis, scaffolds containing BMP-2 + MMP-10 at variable ratios or BMP-2 + Alendronate (ALD) were prepared. Systems were characterized and tested in vitro on healthy and OP mesenchymal stem cells and in vivo bone formation was studied on healthy and OP animals. Therapeutic molecules were efficiently encapsulated into PLGA microspheres and embedded into chitosan foams. The use of PLGA (poly(lactic-co-glycolic acid)) microspheres as therapeutic molecule reservoirs allowed them to achieve an in vitro and in vivo controlled release. A beneficial effect on the alkaline phosphatase activity of non-OP cells was observed for both combinations when compared with BMP-2 alone. This effect was not detected on OP cells where all treatments promoted a similar increase in ALP activity compared with control. The in vivo results indicated a positive effect of the BMP-2 + MMP-10 combination at both of the doses tested on tissue repair for OP mice while it had the opposite effect on non-OP animals. This fact can be explained by the scaffold’s slow-release rate and degradation that could be beneficial for delayed bone regeneration conditions but had the reverse effect on healthy animals. Therefore, the development of adequate scaffolds for bone regeneration requires consideration of the tissue catabolic/anabolic balance to obtain biomaterials with degradation/release behaviors suited for the existing tissue status

Preparation de particules pour inhalation

Cette invention se rapporte à des particules, dans lesquelles sont incorporés un tensioactif et/ou un complexe hydrophyle ou hydrophobe constitué par un agent thérapeutique chargé positivement ou négativement et par une molécule chargée de charge opposée pour l'administration de médicaments dans le système pulmonaire, ainsi qu'à des procédés pour la synthèse et l'administration de ces particules. Dans un mode de réalisation préféré, les particules sont constituées d'un matériau biodégradable et possèdent une densité après tassement inférieure à 0,4 g/cm et un diamètre médian massique compris entre 5 mu m et 30 mu m, qui produisent ensemble un diamètre aérodynamique des particules compris approximateivement entre 1 et 3 microns. Ces particules peuvent être formées de matériaux biodégradables, tels que des polymères biodégradables. Ces particules peuvent par exemple être formées d'acide polylacétique ou d'acide polyglycolique ou de copolymères de ceux-ci. Dans une variante, ces particules peuvent être formées uniquement d'un agent thérapeutique ou diagnostique et d'un tensioactif. Les tensioactifs peuvent être incorporés sur la surface des particules, par exemple par enrobage de la particule après sa formation, ou par incorporation du tensioactif dans le matériau formant la particule avant sa formation. Ces tensioactifs sont par exemple des phosphoglycérides, tels que la dipalmitoyl-phosphatidylcholine (DPPC). Ces particules peuvent être efficacement atomisées pour être administrées à l'appareil respiratoire, afin de permettre l'apport systémique ou local d'une grande variété d'agents thérapeutiques. La formation de complexes d'agents thérapeutiques chargés positivement ou négativement avec des molécules de charge opposée peut permettre de régler le taux de libération de ces agents dans le sang après leur administration