Assessment of the advantages and limitations of an innovative silk fibroin scaffold for the reconstruction of the anterior cruciate ligament with preclinical in vitro and in vivo evaluations.

The gold standard treatment in anterior cruciate ligament (ACL) reconstruction involves autologous tissue transplantation, but this can have complications. Artificial grafts are an alternative, but the best option is debated. This study aimed to assess the biocompatibility and integration of a silk fibroin textile prosthesis (SF-TP) with peri-implant bone tissue and the native ACL.

In vitro cell delivery by gelatin microspheres prepared in water-in-oil emulsion.

The regeneration of injured or damaged tissues by cell delivery approaches requires the fabrication of cell carriers (e.g., microspheres, MS) that allow for cell delivery to limit cells spreading from the injection site.

Polysaccharide-based hydrogels with tunable composition as 3D cell culture systems.

Background: To date, cell cultures have been created either on 2-dimensional (2D) polystyrene surfaces or in 3-dimensional (3D) systems, which do not offer a controlled chemical composition, and which lack the soft environment encountered in vivo and the chemical stimuli that promote cell proliferation and allow complex cellular behavior. In this study, pectin-based hydrogels were developed and are proposed as versatile cell culture systems.

Methods: Pectin-based hydrogels were produced by internally crosslinking pectin with calcium carbonate at different initial pH, aiming to control crosslinking kinetics and degree.

Polyurethane foam scaffold as in vitro model for breast cancer bone metastasis.

Unlabelled: Breast cancer (BC) represents the most incident cancer case in women (29%), with high mortality rate. Bone metastasis occurs in 20-50% cases and, despite advances in BC research, the interactions between tumor cells and the metastatic microenvironment are still poorly understood. In vitro 3D models gained great interest in cancer research, thanks to the reproducibility, the 3D spatial cues and associated low costs, compared to in vivo and 2D in vitro models.

Electrospun silk fibroin-gelatin composite tubular matrices as scaffolds for small diameter blood vessel regeneration.

In this work an innovative method to obtain natural and biocompatible small diameter tubular structures is proposed. The biocompatibility and good mechanical properties of electrospun silk fibroin tubular matrices (SFts), extensively studied for tissue engineering applications, have been coupled with the excellent cell interaction properties of gelatin. In fact, an innovative non-cytotoxic gelatin gel, crosslinked in mild conditions via a Michael-type addition reaction, has been used to coat SFt matrices and obtain SFt/gel structures (I.

Poly-paper: a sustainable material for packaging, based on recycled paper and recyclable with paper.

Background: Until now, environmental sustainability issues are almost entirely unsolved for packaging materials. With the final aim of finding materials with a single recycling channel, cellulose fiber/poly(vinyl)alcohol composites were investigated.

Methods: After extrusion and injection molding, samples of composite with different cellulose fiber content (30%, 50% and 70% w/w) were tested.

Novel class of collector in electrospinning device for the fabrication of 3D nanofibrous structure for large defect load-bearing tissue engineering application.

Adequate porosity, appropriate pore size, and 3D-thick shape are crucial parameters in the design of scaffolds, as they should provide the right space for cell adhesion, spreading, migration, and growth. In this work, a novel design for fabricating a 3D nanostructured scaffold by electrospinning was taken into account. Helical spring-shaped collector was purposely designed and used for electrospinning PCL fibers.

Small diameter electrospun silk fibroin vascular grafts: Mechanical properties, in vitro biodegradability, and in vivo biocompatibility.

To overcome the drawbacks of autologous grafts currently used in clinical practice, vascular tissue engineering represents an alternative approach for the replacement of small diameter blood vessels. In the present work, the production and characterization of small diameter tubular matrices (inner diameter (ID)=4.5 and 1.

Exploiting novel sterilization techniques for porous polyurethane scaffolds.

Porous polyurethane (PU) structures raise increasing interest as scaffolds in tissue engineering applications. Understanding the effects of sterilization on their properties is mandatory to assess their potential use in the clinical practice. The aim of this work is the evaluation of the effects of two innovative sterilization techniques (i.

Nano/micro hybrid scaffold of PCL or P3HB nanofibers combined with silk fibroin for tendon and ligament tissue engineering.

A novel biodegradable nano/micro hybrid structure was obtained by electrospinning P3HB or PCL nanofibers onto a twisted silk fibroin (SF) structure, with the aim of fabricating a suitable scaffold for tendon and ligament tissue engineering. The electrospinning (ES) processing parameters for P3HB and PCL were optimized on 2D samples, and applied to produce two different nano/micro hybrid constructs (SF/ES-PCL and SF/ES-P3HB).Morphological, chemico-physical and mechanical properties of the novel hybrid scaffolds were evaluated by SEM, ATR FT-IR, DSC, tensile and thermodynamic mechanical tests.

Reactive hydroxyapatite fillers for pectin biocomposites.

In this work, a novel injectable biocomposite hydrogel is produced by internal gelation, using pectin as organic matrix and hydroxyapatite either as crosslinking agent and inorganic reinforcement. Tunable gelling kinetics and rheological properties are obtained varying the hydrogels' composition, with the final aim of developing systems for cell immobilization. The reversibility by dissolution of pectin-hydroxyapatite hydrogels is achieved with saline solutions, to possibly accelerate the release of the cells or active agents immobilized.

Injectable pectin hydrogels produced by internal gelation: pH dependence of gelling and rheological properties.

The production of injectable pectin hydrogels by internal gelation with calcium carbonate is proposed. The pH of pectin was increased with NaOH or NaHCO3 to reach physiological values. The determination of the equivalence point provided evidence that the pH can be more precisely modulated with NaHCO3 than with NaOH.

In vitro study on silk fibroin textile structure for anterior cruciate ligament regeneration.

A novel hierarchical textile structure made of silk fibroin from Bombyx mori capable of matching the mechanical performance requirements of anterior cruciate ligament (ACL) and in vitro cell ingrowth is described. This sericin-free, Silk Fibroin Knitted Sheath with Braided Core (SF-KSBC) structure was fabricated using available textile technologies. Micro-CT analysis confirmed that the core was highly porous and had a higher degree of interconnectivity than that observed for the sheath.

In vivo regeneration of elastic lamina on fibroin biodegradable vascular scaffold.

Purpose: There is an increasing need for vascular grafts in the field of surgical revascularization. Artificial grafts offer alternative strategies to autologous tissue, however, small caliber (diameter <6 mm) 
vascular prosthesis are associated with a high incidence of thrombosis and early failure. Despite promising results, vascular tissue engineering is not yet a clinical reality due to the complexity of this approach.

Collagen-reinforced electrospun silk fibroin tubular construct as small calibre vascular graft.

None of the replacements proposed in the literature for small-calibre blood vessels (SCBV) fully satisfies the stringent requirements that these grafts have to fulfil. Here, an electrospun silk fibroin tubular construct is hybridized with type I collagen gel to produce a biomimetic SCBV graft with physiologically relevant compliance and burst pressure and optimal cytocompatibility. The hybridization of the two polymers results in the formation of a nanofibrillar hydrated matrix, where the collagen gel enhances the mechanical properties of the SF tubular construct and improves the early response of the material to in vitro cell adhesion and proliferation.

Preparation and characterization of shape memory polymer scaffolds via solvent casting/particulate leaching.

Purpose: Porous Shape Memory Polymers (SMPs) are ideal candidates for the fabrication of defect fillers, able to support tissue regeneration via minimally invasive approaches. In this regard, control of pore size, shape and interconnection is required to achieve adequate nutrient transport and cell ingrowth. Here, we assessed the feasibility of the preparation of SMP porous structures and characterized their chemico-physical properties and in vitro cell response.

New perspectives in cell delivery systems for tissue regeneration: natural-derived injectable hydrogels.

Natural polymers, because of their biocompatibility, availability, and physico-chemical properties have been the materials of choice for the fabrication of injectable hydrogels for regenerative medicine. In particular, they are appealing materials for delivery systems and provide sustained and controlled release of drugs, proteins, gene, cells, and other active biomolecules immobilized.In this work, the use of hydrogels obtained from natural source polymers as cell delivery systems is discussed.

Effects of the magnetic resonance field on breast tissue expanders.

Background: Tissue expansion for breast reconstruction after mastectomy is a safe and effective procedure. A magnetic resonance imaging (MRI) scan can be requested for patients with a breast expander to evaluate concurrent diseases. The electromagnetic field of the MR can interfere with biomedical devices, resulting in potential hazards, compromising the diagnosis, or creation of artifacts.

Assessment of scaffold porosity: the new route of micro-CT.

A complete morphologic characterization of porous scaffolds for tissue engineering application is fundamental, as the architectural parameters, in particular porosity, strongly affect the mechanical and biological performance of the structures. Therefore, appropriate techniques for this purpose need to be selected. Several techniques for the assessment of scaffold porosity have been proposed, including Scanning Electron Microscopy observation, mercury and liquid extrusion porosimetry, gas pycnometry, and capillary flow porometry.

Poly(ethylene glycol) and hydroxy functionalized alkane phosphate self-assembled monolayers reduce bacterial adhesion and support osteoblast proliferation.

Purpose: Presently there is interest today in designing improved titanium surfaces capable of high bioactivity in order to promote strong anchorage of the bone surrounding implants while at the same time discouraging bioadhesion. Poly(ethylene glycol)-modified (PEG) alkane phosphate and OH-terminated alkane phosphates have been demonstrated to be spontaneously adsorbed onto titanium oxide surfaces and produce surfaces with different protein resistance in relation to the PEG surface density. This study aims to evaluate caries-associated Streptococcus mutans (S.

Trends in biomedical engineering: focus on Smart Bio-Materials and Drug Delivery.

The present article reviews on different research lines, namely: drug and gene delivery, surface modification/modeling, design of advanced materials (shape memory polymers and biodegradable stents), presently developed at Politecnico di Milano, Italy. For gene delivery, non-viral polycationic-branched polyethylenimine (b-PEI) polyplexes are coated with pectin, an anionic polysaccharide, to enhance the polyplex stability and decrease b-PEI cytotoxicity. Perfluorinated materials, specifically perfluoroether, and perfluoro-polyether fluids are proposed as ultrasound contrast agents and smart agents for drug delivery.

Enzymatic cross-linking of human recombinant elastin (HELP) as biomimetic approach in vascular tissue engineering.

The use of polymers naturally occurring in the extracellular matrix (ECM) is a promising strategy in regenerative medicine. If compared to natural ECM proteins, proteins obtained by recombinant DNA technology have intrinsic advantages including reproducible macromolecular composition, sequence and molecular mass, and overcoming the potential pathogens transmission related to polymers of animal origin. Among ECM-mimicking materials, the family of recombinant elastin-like polymers is proposed for drug delivery applications and for the repair of damaged elastic tissues.

Microcontact printing of fibronectin on a biodegradable polymeric surface for skeletal muscle cell orientation.

Background And Objectives: Micropatterning and microfabrication techniques have been widely used to control cell adhesion and proliferation along a preferential direction according to contact guidance theory. One of these techniques is microcontact printing, a soft lithographic technique based on the transfer of a "molecular ink" from an elastomeric stamp to a surface. This method allows the useful attachment of biomolecules in a few seconds on a variety of surfaces with sub-micrometer resolution and control, without modifying the biomolecule properties.

Fabrication of chemically cross-linked porous gelatin matrices.

Purpose: The aim of this study was to chemically cross-link gelatin, by reacting its free amino groups with an aliphatic diisocyanate.

Methods: To produce hydrogels with controllable properties, the number of reacting amino groups was carefully determined. Porosity was introduced into the gelatin-based hydrogels through the lyophilization process.