Development and evaluation of hyaluronan nanocomposite conduits for neural tissue regeneration.

Hyaluronan-based hydrogels are among the most promising neural tissue engineering materials because of their biocompatibility and the immunomodulation capabilities of their degradation byproducts. Despite these features, the problems related to their handling and mechanical properties have not yet been solved. In the present work it is proposed to address these drawbacks through the development of nanohybrid materials in which different nanometric phases (carbon nanotubes, mesoporous silica nanoparticles) are embedded in a crosslinked hyaluronan matrix.

Improved Mechanical, Thermal, and Hydrophobic Properties of PLA Modified with Alkoxysilanes by Reactive Extrusion Process.

An eco-friendly strategy for the modification of polylactic acid (PLA) surface properties, using a solvent-free process, is reported. Reactive extrusion (REX) allowed the formation of new covalent bonds between functional molecules and the PLA polymeric matrix, enhancing its mechanical properties and modifying surface hydrophobicity. To this end, the PLA backbone was modified using two alkoxysilanes, phenyltriethoxysilane and N-octyltriethoxysilane.

Role of Electrospinning Parameters on Poly(Lactic-co-Glycolic Acid) and Poly(Caprolactone-co-Glycolic acid) Membranes.

Poly(lactic-co-glycolic acid) (PLGA) and poly(caprolactone-co-glycolic acid) (PCLGA) solutions were electrospun into membranes with tailored fiber diameter of 1.8 μm. This particular fiber diameter was tuned depending on the used co-polymer by adjusting the electrospinning parameters that mainly influence the fiber diameter.

Role of Curing Temperature of Poly(Glycerol Sebacate) Substrates on Protein-Cell Interaction and Early Cell Adhesion.

A novel procedure to obtain smooth, continuous polymeric surfaces from poly(glycerol sebacate) (PGS) has been developed with the spin-coating technique. This method proves useful for separating the effect of the chemistry and morphology of the networks (that can be obtained by varying the synthesis parameters) on cell-protein-substrate interactions from that of structural variables. Solutions of the PGS pre-polymer can be spin-coated, to then be cured.

Influence of pre-polymerisation atmosphere on the properties of pre- and poly(glycerol sebacate).

Poly(glycerol sebacate) (PGS) is a versatile biodegradable biomaterial on account of its adjustable mechanical properties as an elastomeric polyester. Nevertheless, it has shown dissimilar results when synthesised by different research groups under equivalent synthesis conditions. This lack of reproducibility proves how crucial it is to understand the effect of the parameters involved on its manufacturing and characterize the polymer networks obtained.

Amphipathic Substrates Based on Crosslinker-Free Poly(ε-Caprolactone):Poly(2-Hydroxyethyl Methacrylate) Semi-Interpenetrated Networks Promote Serum Protein Adsorption.

A simple procedure has been developed to synthesize uncrosslinked soluble poly(hydroxyethyl methacrylate) (PHEMA) gels, ready for use in a subsequent fabrication stage. The presence of 75 wt % methanol (MetOH) or dimethylformamide (DMF) impedes lateral hydroxyl-hydroxyl hydrogen bonds between PHEMA macromers to form during their solution polymerization at 60 °C, up to 24 h. These gels remain soluble when properly stored in closed containers under cold conditions and, when needed, yield by solvent evaporation spontaneous physically-crosslinked PHEMA adapted to the mould used.

Candidate Polyurethanes Based on Castor Oil (), with Polycaprolactone Diol and Chitosan Additions, for Use in Biomedical Applications.

Polyurethanes are widely used in the development of medical devices due to their biocompatibility, degradability, non-toxicity and chemical versatility. Polyurethanes were obtained from polyols derived from castor oil, and isophorone diisocyanate, with the incorporation of polycaprolactone-diol (15% /) and chitosan (3% /). The objective of this research was to evaluate the effect of the type of polyol and the incorporation of polycaprolactone-diol and chitosan on the mechanical and biological properties of the polyurethanes to identify the optimal ones for applications such as wound dressings or tissue engineering.

Wideband phantoms of different body tissues for heterogeneous models in body area networks.

One of the key issues about wireless technologies is their interaction with the human body. The so-called internet of things will comprise many devices that will transmit either around or through the human body. These devices must be tested either in their working medium, when possible, or in the most realistic one.

Influence of synthesis parameters on hyaluronic acid hydrogels intended as nerve conduits.

Hydrogels have widely been proposed lately as strategies for neural tissue regeneration, but there are still some issues to be solved before their efficient use in tissue engineering of trauma, stroke or the idiopathic degeneration of the nervous system. In a previous work of the authors a novel Schwann-cell structure with the shape of a hollow cylinder was obtained using a three-dimensional conduit based in crosslinked hyaluronic acid as template. This original engineered tissue of tightly joined Schwann cells obtained in a conduit lumen having 400 μm in diameter is a consequence of specific cell-material interactions.

in vitro development of bioimplants made up of elastomeric scaffolds with peptide gel filling seeded with human subcutaneous adipose tissue-derived progenitor cells.

Myocardial tissue lacks the ability to regenerate itself significantly following a myocardial infarction. Thus, new strategies that could compensate this lack are of high interest. Cardiac tissue engineering (CTE) strategies are a relatively new approach that aims to compensate the tissue loss using combination of biomaterials, cells and bioactive molecules.

Experimental Path Loss Models for In-Body Communications Within 2.36-2.5 GHz.

Biomedical implantable sensors transmitting a variety of physiological signals have been proven very useful in the management of chronic diseases. Currently, the vast majority of these in-body wireless sensors communicate in frequencies below 1 GHz. Although the radio propagation losses through biological tissues may be lower in such frequencies, e.

Peptide gel in a scaffold as a composite matrix for endothelial cells.

The performance of a composite environment with human umbilical vein endothelial cells (HUVECs) has been studied to provide an in vitro proof of concept of their potential of being easily vascularized. These cells were seeded in 1 mm thick scaffolds whose pores had been filled with a self-assembling peptide gel, seeking to improve cell adhesion, and viability of these very sensitive cells. The combination of the synthetic elastomer poly(ethyl acrylate), PEA, scaffold and the RAD16-I peptide gel provides cells with a friendly ECM-like environment inside a mechanically resistant structure.

Engineered 3D bioimplants using elastomeric scaffold, self-assembling peptide hydrogel, and adipose tissue-derived progenitor cells for cardiac regeneration.

Contractile restoration of myocardial scars remains a challenge with important clinical implications. Here, a combination of porous elastomeric membrane, peptide hydrogel, and subcutaneous adipose tissue-derived progenitor cells (subATDPCs) was designed and evaluated as a bioimplant for cardiac regeneration in a mouse model of myocardial infarction. SubATDPCs were doubly transduced with lentiviral vectors to express bioluminescent-fluorescent reporters driven by constitutively active, cardiac tissue-specific promoters.

Design and assembly procedures for large-sized biohybrid scaffolds as patches for myocardial infarct.

Objective: To assemble a biohybrid cardiac patch consisting of a large (5 × 5 cm) elastomer scaffold whose pores are filled with a self-assembling peptide (SAP) gel entrapping adipose stem cells, to be used as a novel implant in a big animal model (sheep) of myocardial infarction. The study focuses on the way to determine optimal procedures for incorporating the SAP solution and the cells in the patch to ensure cell colonization and a homogeneous cell distribution in the construct before implantation. The problems associated with the scale-up of the different procedures raised by the large size of the construct are discussed.

Unsupervised segmentation of brain regions with similar microstructural properties: application to alcoholism.

In this work, a novel brain MRI segmentation approach evaluates microstructural differences between groups. Going further from the traditional segmentation of brain tissues (white matter -WM-, gray matter -GM- and cerebrospinal fluid -CSF- or a mixture of them), a new way to classify brain areas is proposed using their microstructural MR properties. Eight rats were studied using the proposed methodology identifying regions which present microstructural differences as a consequence on one month of hard alcohol consumption.

One-dimensional migration of olfactory ensheathing cells on synthetic materials: experimental and numerical characterization.

Olfactory ensheathing cells (OECs) are of great interest for regenerative purposes since they are believed to aid axonal growth. With the view set on the strategies to achieve reconnection between neuronal structures, it is of great importance to characterize the behaviour of these cells on long thread-like structures that may efficiently guide cell spread in a targeted way. Here, rat OECs were studied on polycaprolactone (PCL) long monofilaments, on long bars and on discs.

Channeled scaffolds implanted in adult rat brain.

Scaffolds with aligned channels based on acrylate copolymers, which had previously demonstrated good compatibility with neural progenitor cells were studied as colonizable structures both in vitro with neural progenitor cells and in vivo, implanted without cells in two different locations, in the cortical plate of adult rat brains and close to the subventricular zone. In vitro, neuroprogenitors colonize the scaffold and differentiate into neurons and glia within its channels. When implanted in vivo immunohistochemical analysis by confocal microscopy for neural and endothelial cells markers demonstrated that the scaffolds maintained continuity with the surrounding neural tissue and were colonized by GFAP-positive cells and, in the case of scaffolds implanted in contact with the subventricular zone, by neurons.

Mimicking natural dentin using bioactive nanohybrid scaffolds for dentinal tissue engineering.

Synthetic materials mimicking the internal porous structure of natural dentin were prepared as nanohybrid matrix scaffolds made of poly(ethyl methacrylate-co-hydroxyethyl acrylate), pure and with a sol-gel-derived interpenetrated silica nanophase, with aligned tubular pores in the micrometer range typical of dentinal tissue. Some of them were internally coated with a layer of hydroxyapatite by immersion in simulated body fluid. Their physicochemical and mechanical properties were investigated.

Microcomputed tomography and microfinite element modeling for evaluating polymer scaffolds architecture and their mechanical properties.

Detailed knowledge of the porous architecture of synthetic scaffolds for tissue engineering, their mechanical properties, and their interrelationship was obtained in a nondestructive manner. Image analysis of microcomputed tomography (microCT) sections of different scaffolds was done. The three-dimensional (3D) reconstruction of the scaffold allows one to quantify scaffold porosity, including pore size, pore distribution, and struts' thickness.

Clinical software for the assessment of trabecular bone disease in distal radius based on a magnetic resonance structural analysis.

As Bone Mineral Density has been demonstrated to be insufficient to elaborate a correct diagnosis of bone diseases such as osteoporosis, a new software tool called EsTra has been developed in order to estimate the most significant structural parameters of trabecular bone microarchitecture. In EsTra, different techniques as automated segmentation, snakes, filtering, skeletonization, voxel classification and three-dimensional reconstruction are applied to Magnetic Resonance images of distal radius and ulna. A microarchitectural study is also carried out from three different viewpoints involving morphological, topological and fractal analysis.

ICA for ovary tissue classification of perfusion magnetic resonance images.

In this study, a method to segment ovary Magnetic Resonance (MR) images and distinguish healthy tissue from cysts has been described. Through the application of independent component analysis (ICA) to a set of perfusion MR images it was possible to extract the output independent components and their corresponding signal-time curves. After examining and analyzing this result, a polynomial approach was computed to represent the main features of each curve, and automated particular selection of independent components was obtained by applying a Bayesian information criterion able to show the most relevant components.

Volume mesh generation and finite element analysis of trabecular bone magnetic resonance images.

In order to help the assessment of trabecular bone diseases and complement Dual X-Ray Absorptiometry (DXA) in diagnosis process, it is needed an accurate mechanical characterization of trabecular bone structure to estimate the risk of fracture and evaluate micro-architecture deterioration. As Finite Element modeling has become a well-established method for analysis of complex structures, an algorithm has been developed to build a Finite Element mesh from three-dimensional reconstruction information in voxels. Generated mesh is loaded in a Finite Element analysis software in order to simulate micro-architecture mechanical behavior under compression conditions.