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Pathological angiogenesis is a crucial attribute of several chronic diseases such as cancer, age-related macular degeneration, and osteoarthritis (OA). In the case of OA, pathological angiogenesis mediated by the vascular endothelial growth factor (VEGF), among other factors, contributes to cartilage degeneration and to implants rejection. In line with this, the use of the anti-VEGF bevacizumab (BVZ) has been shown to prevent OA pro- gression and support cartilage regeneration. The aim of this work was to functionalize a medical grade collagen with poly (lactic-co-glycolic acid) (PLGA) microparticles containing BVZ via three-dimensional (3D) printing to target pathological angiogenesis. First, the effect of several formulation parameters on the encapsulation and release of BVZ from PLGA microparticles was studied. Then, the anti-angiogenic activity of released BVZ was tested in a 3D cell model. The 3D printability of the microparticle-loaded collagen ink was tested by evaluating the shape fidelity of 3D printed structures. Results showed that the release and the encapsulation efficiency of BVZ could be tuned as a function of several formulation parameters. In addition, the released BVZ was observed to reduce vascularization by human umbilical vein endothelial cells. Finally, the collagen ink with embedded BVZ microparticles was successfully printed, leading to shape-stable meniscus-, nose- and auricle-like structures. Taken altogether, we defined the conditions for the successful combination of BVZ-loaded microparticles with the 3D printing of a medical grade collagen to target pathological angiogenesis.

In recent years, many research studies have focused on the application of 3D printing in the production of orthopaedic back braces. Several advantages, such as the ability to customise complex shapes, improved therapeutic effect and reduced production costs place this technology at the forefront in the ongoing evolution of the orthopaedic sector. In this work, four different materials, two of them poly(lactic acid) (PLA) and two of them poly(ethylene terephthalate glycol) (PETG), were characterised from a thermal, mechanical, rheological and morphological point of view. Our aim was to understand the effects of the material properties on the quality and functionality of a 3D-printed device. The specimens were cut from 3D-printed hemi-cylinders in two different orientation angles. Our results show that PETG-based samples have the best mechanical properties in terms of elastic modulus and elongation at break. The PLA-based samples demonstrated typical brittle behaviour, with elongation at break one order of magnitude lower. Impact tests demonstrated that the PETG-based samples had better properties in terms of energy absorption. Moreover, 3D-printed PETG samples demonstrated a better surface finishing with a more homogenous fibre–fibre interface. In summary, we demonstrate that the right choice of material and printing conditions are fundamental to satisfy the quality and functionality required for a scoliosis back brace.

Wound care management urgently needs the development of innovative smart wound dressings. The complexity of the wound often requires the use of personalized medication and the advent of three-dimensional (3D) bioprinting fits strongly with this need. In this view, in the present work a methacrylated hyaluronic acid (MeHA) bioink was tested for the fabrication of advanced smart patches as a delivery system of exosomes derived from human mesenchymal stem cells (hMSC-EXOs) suitable for wound healing purposes. MeHA patches were realized by 3D bioprinting technique and they were loaded with hMSC-EXOs. The 3D printed MeHA patches revealed improved mechanical performance, appropriate swelling ratio, extended degradation time, and suitable biocompatibility. Furthermore, MeHA patches loaded with hMSC-EXOs improved the proliferation, migration, angiogenic ability, and expression of specific markers related to wound healing process in human fibroblasts and human endothelial cells.

Il presente lavoro è una overview delle tecniche di fabbricazione degli scaffold per la rigenerazione del tessuto osseo e cartilagineo

Over the past few years, different in vitro and in vivo studies have been highlighting the great potentiality of hyaluronic acid (HA) as a biomaterial in wound healing treatment thanks to its good capability to induce mesenchymal and epithelial cell growth and differentiation, angiogenesis, and collagen deposition. However, the need to improve its mechanical properties as well as its residence time has led scientists to study new functionalization strategies. In this work, chemically modified HA-based hydrogels were obtained by methacrylic and maleic functionalization. Methacrylated (MEHA) and maleated HA (MAHA) hydrogels have shown important physico-chemical properties. The present study provides a deeper insight into the biocompatibility of both synthesized materials and their effects on tissue inflammation using in vitro and in vivo models. To this aim, different cell lines involved in wound healing, human dermal fibroblasts, human adipose-derived stem cells and human umbilical vein endothelial cells, were seeded on MEHA and MAHA hydrogels. Furthermore, an inflammation study was carried out on a murine macrophage cell line to assess the effects of both hydrogels on inflammatory and anti-inflammatory interleukin production. The results showed that both MAHA and MEHA supported cell proliferation with anti-inflammation ability as highlighted by the increased levels of IL-10 (57.92 ± 9.87 pg mL-1 and 68.08 ± 13.94 pg mL-1, for MEHA and MAHA, respectively). To investigate the inflammatory response at tissue/implant interfaces, an in vivo study was also performed by subcutaneous implantation of the materials in BALB/c mice for up to 28 days. In these analyses, no significant chronic inflammation reaction was demonstrated in either MEHA or MAHA in the long-term implantation.

Attività di ricerca condotta nell'ambito del progetto riguardante lo sviluppo di un bioink per la realizzazione di scaffold per la rigenerazione del menisco umano

Realizzazione di uno scaffold per la rigenerazione del menisco

The electromagnetic properties of structures with spatially periodic distributed graded refractive index were investigated in the terahertz frequency range. The band structure and electromagnetic response of material with harmonically distributed refractive index were calculated and analyzed. The analytical expressions for frequencies of the first and second bandgap are derived. 3D printed gyroid based architectures were proven to be harmonically graded refractive index structures with designed bandgaps in THz frequency ranges. The transmission coefficient of thermoplastic polyurethane-based samples were experimentally measured in the frequency range 100–500 GHz and compared with theoretical results. Due to losses in the real world produced samples, the predicted response is significantly dumped in the terahertz range and only traces of band gaps are experimentally observed. This funding paves the way toward a new generation of 3D printed THz components for gradient-index optics applications.

The limited number of commercially available photocrosslinkable resins for stereolithography has often been considered the main limitation of this technique. In this manuscript, a photocrosslinkable poly-ε-caprolactone (PCL) has been synthesized by a two-step method starting from ring opening polymerization (ROP) of ε-caprolactone. Hydroxyethyl vinyl ether (HEVE) has been used both as the initiator of ROP and as photo-curable functional group to obtain a vinyl poly-ε-caprolactone (VPCL). The following reaction of VPCL with fumaryl chloride (FuCl) results in a divinyl-fumarate polycaprolactone (VPCLF). Moreover, a catalyst based on Al, instead of the most popular Tin(II) 2-ethylhexanoate, has been employed to reduce the cytotoxicity of the material. VPCLF has been successfully used, in combination with N-vinyl-pyrrolidone (NVP), to fabricate 3D porous scaffolds by micro-stereolithography (μ-SL) with mathematically defined architectures.

Hyaluronic acid (HA)-based hydrogels are one of the most promising naturally derived biomaterials for tissue engineering applications, as they can play an important role in many key cellular processes. In this study, HA was chemically functionalized with photo-cross-linkable motifs by reacting with methacrylic anhydride (MA) to obtain methacrylated hyaluronic acid (MeHA). A range of MA/HA molar ratios was used to obtain different degrees of substitution (DS) ranging from 3.5% to 74.5%, as showed by nuclear magnetic resonance and attenuated total reflection spectroscopy. By fine tuning the DS, the chemical reaction parameters, and the polymer concentration, it was demonstrated the possibility to tailor their mechanical features. Double network (DN) hydrogels were prepared through the synergic use of MeHA and polyethylene glycole diacrylate (PEGDA). To improve the biological properties of DN hydrogels, bioactive solid signals such as hydroxyapatite nanoparticles (HAp) prepared by sol-gel approach were used in combination with DN hydrogels to obtain an advanced composite material with dual function in terms of mechanical and biological support for soft/hard tissue formation. The results highlighted that composite-DN hydrogels showed a 10-time increase of the storage modulus, if compared to neat MeHA, and an early alkaline phosphatase expression from human mesenchymal stem cells in basal medium. This work can be considered a first systematic approach for the designing of photo-cross-linkable hydrogels, based on a combination of natural/synthetic polymers and HAp, that could be applied in three-dimensional additive manufacturing techniques such as stereolithography. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 3079-3089, 2018.

A vinyl-terminated Polycaprolactone has been developed for tissue engineering applications using a one-step synthesis and functionalization method based on Ring Opening Polymerization (ROP) of ԑ-caprolactone, with Hydroxyl Ethyl Vinyl Ether (HEVE) acting both as the initiator of ROP and as photo-curable functional group. The proposed method employs a catalyst based on Al, instead of the most popular Tin(II) 2-ethylhexanoate, to reduce the cytotoxicity. Following the synthesis of the vinyl-terminated polycaprolactone, its reaction with Fumaryl Chloride (FuCl) results in a divinyl-fumarate polycaprolactone (VPCLF). The obtained polymers were thoroughly characterized using Fourier Transform Infrared Spectroscopy (FTIR) and gel permeation chromatography (GPC) techniques. The polymer has been successfully employed, in combination with N-vinyl Pyrrolidone (NVP), to fabricate films and computer-designed porous scaffolds by micro-stereolithography (μ-SL) with Gyroid and Diamond architectures. Characterization of the networks indicated the influence of NVP content on the network properties. Human Mesenchymal Stem Cells (hMSCs) adhered and spread onto VPCLF/NVP networks showing good biological properties and no cytotoxic effect.

The limited number of resins, available for stereolithography applications, is one of the key drivers in research applied to rapid prototyping. In this work an acrylic photocrosslinkable resin based on methyl methacrylate (MMA), butyl methacrylate (BMA) and poly(ethylene glycol) dimethacrylate (PEGDA) was developed with different composition and characterized in terms of mechanical, thermal and biological behaviour. Two different systems have been developed using different amount of reagent. The influence of every components have been evaluated on the final characteristic of the resin in order to optimize the final composition for applications in bone tissue engineering. The crosslinked materials showed good mechanical properties and thermal stabilities and moreover cytotoxicity test confirms good biocompatibility with no cytotoxic effect on cells metabolism. Moreover two different treatments have been proposed, using fetal bovine serum (FBS) and methanol (MeOH), in order to improve cell recognition of the surfaces. Samples threatened with MeOH allow cell adhesion and survival, promoting spreading, elongation and fusion of C2C12 muscle myoblast cells., Graphical abstract Image 1, Highlights • Photocrosslinkable biocompatible resin for application in tissue engineering. • Surface treatment to improve materials wettability. • Myoblast spreading and elongation on photocrosslinked modified surfaces.

The limited number of commercially available photocrosslinkable resins for stereolithography has often been considered the main limitation of this technique. In this manuscript, a photocrosslinkable poly-e-caprolactone (PCL) has been synthesized by a two-step method starting from ring opening polymerization (ROP) of e-caprolactone. Hydroxyethyl vinyl ether (HEVE) has been used both as the initiator of ROP and as photo-curable functional group to obtain a vinyl poly-e-caprolactone (VPCL). The following reaction of VPCL with fumaryl chloride (FuCl) results in a divinyl-fumarate polycaprolactone (VPCLF). Moreover, a catalyst based on Al, instead of the most popular Tin(II) 2-ethylhexanoate, has been employed to reduce the cytotoxicity of the material. VPCLF has been successfully used, in combination with N-vinyl-pyrrolidone (NVP), to fabricate 3D porous scaffolds by micro-stereolithography (μ-SL) with mathematically defined architectures.

The objective of this study is to demonstrate the possibility of obtaining a completely customized orthosis through the use of multi-material 3-D printing technique. Additive manufacturing with multi-material enables to print objects with two different materials at the same time. Two immiscible materials Polylactic Acid (PLA), Thermoplastic Polyurethane (TPU) are chosen to give the orthosis a good trade-off between flexibility and rigidity. Results show that with this innovative technology it is possible not only create complex functional geometries but also to overcome some of the issues associated with traditional immobilization techniques (plaster of Paris splints). Tensile and impact tests are performed on 3D printed specimens to analyze their toughness, rigidity and flexibility. Three different prototypes are developed varying the composition and the organization of the materials used. Results show that the proposed approach is capable of addressing all the issues associated with conventional plaster casts.

In recent years, 3D printing gained considerable attention in the orthopedic sector. This work evaluates the feasibility of producing orthopedic scoliosis braces by 3D printing, comparing performance and costs with classical thermoforming procedures. Critical parameters, such as manufacture time, mechanical properties, weight, and comfort are carefully considered. Polyethylene terephthalate glycol-modified (PETG) was selected among the several filaments materials present on the market. Printed samples were analyzed with electronic microscope, tensile, and impact tests and compared with thermoformed polyethylene (PE) and polypropylene (PP) samples. Moreover, a cost analysis was carried out for the specific application. The thermoformed brace of a volunteer patient affected by scoliosis was reproduced using reverse-engineering techniques. The model was then printed as a single piece and postprocessed by an expert orthotist. Subsequently, the patient wore the brace in a pilot case to compare comfort and mechanical effectiveness. Results show that the 3D printing fabrication method is able to provide a valid alternative to the current fabrication methods, being also very competitive in terms of costs. The morphological analysis does not show critical defects in 3D printed samples, while the mechanical tests highlighted their anisotropy, with an overall brittleness of PETG samples in the direction orthogonal to the fibers. However, in terms of mechanical stresses, a back brace should never reach the polymer yield stress, otherwise the shape would be modified and the therapeutic effect could be compromised. Finally, the patient reported the perception of improved support and no significant comfort differences compared with the thermoformed brace.

Injectable materials represent very attractive ready-to-use biomaterials for application in minimally invasive surgical procedures. It is shown that this approach to treat, for example, vertebral fracture, craniofacial defects, or tumor resection has significant clinical potential in the biomedical field. In the last four decades, calcium phosphate cements have been widely used as injectable materials for orthopedic surgery due to their excellent properties in terms of biocompatibility and osteoconductivity. However, few clinical studies have demonstrated certain weaknesses of these cements, which include high viscosity, long degradation time, and difficulties being manipulated. To overcome these limitations, the use of sol-gel technology has been investigated, which has shown good results for synthesis of injectable calcium phosphate-based materials. In the last few decades, injectable hydrogels have gained increasing attention owing to their structural similarities with the extracellular matrix, easy process conditions, and potential applications in minimally invasive surgery. However, the need to protect cells during injection leads to the development of double network injectable hydrogels that are capable of being cross-linked in situ. This review will provide the current state of the art and recent advances in the field of injectable biomaterials for minimally invasive surgery.

Elastomer-based porous structures realized by selective laser sintering (SLS) are emerging as a new class of attractive multifunctional materials. Herein, a thermoplastic polyurethane (TPU) powder for SLS was modified by 1 wt.% multi-walled carbon nanotube (MWCNTs) or a mixture of MWCNTs and graphene (GE) nanoparticles (70/30 wt/wt) in order to investigate on both the synergistic effect provided by the two conductive nanostructured carbonaceous fillers and the correlation between formulation, morphology, and final properties of SLS printed porous structures. In detail, porous structures with a porosity ranging from 20% to 60% were designed using Diamond (D) and Gyroid (G) unit cells. Results showed that the carbonaceous fillers improve the thermal stability of the elastomeric matrix. Furthermore, the TPU/1 wt.% MWCNTs-GE-based porous structures exhibit excellent electrical conductivity and mechanical strength. In particular, all porous structures exhibit a robust negative piezoresistive behavior, as demonstrated from the gauge factor (GF) values that reach values of about &minus, 13 at 8% strain. Furthermore, the G20 porous structures (20% of porosity) exhibit microwave absorption coefficients ranging from 0.70 to 0.91 in the 12&ndash, 18 GHz region and close to 1 at THz frequencies (300 GHz&ndash, 1 THz). Results show that the simultaneous presence of MWCNTs and GE brings a significant enhancement of specific functional properties of the porous structures, which are proposed as potential actuators with relevant electro-magnetic interference (EMI) shielding properties.

The main driving idea of the present study was the comparison between two different chemical modifications of hyaluronic acid (HA) followed by the development of nanocomposite hydrogels directly in situ by biomineralization of photocrosslinkable HA polymers through sol-gel synthesis. In this way, it has been possible to overcome some limitations due to classical approaches based on the physical blending of inorganic fillers into polymer matrix. To this aim, methacrylated and maleated HA, synthesized with similar degree of substitution (DS) were compared in terms of mechanical and physico-chemical properties. The success of in situ biomineralization was highlighted by reflect Fourier transform infrared spectroscopy and thermogravimetric analysis. Furthermore, mechanical characterization demonstrated the reinforcing effect of inorganic fillers evidencing a strong correlation with DS. The swelling behavior resulted to be correlated with filler concentration. Finally, the cytotoxicity tests revealed the absence of toxic components and an increase of cell proliferation over culture time was observed, highlighting these bio-nanocomposite hyaluronan derivatives as biocompatible hydrogel with tunable properties.

In this study, an innovative polymer blend, based on double network (DN) approach, has been developed by integrating a poly(ethylene glycol) diacrylate (PEGDA) network into a chemically modified hyaluronic acid sodium salt (HAs) hydrogel matrix. Here, the HAs was chemically functionalized with photocrosslinkable moieties by reacting with maleic anhydride (MAA) to obtain a maleated hyaluronic acid (MaHA). Furthermore, nanocomposite DN hydrogels were suitably prepared by physical blending of hydroxyapatite nanoparticles (HAp), obtained by sol-gel synthesis, into the hydrogel. Hydrogels were characterized in terms of physico-chemical, thermal, morphological and mechanical properties. Results showed enhanced mechanical properties and a homogenous microstructure as highlighted by mechanical and morphological investigations. This suggests that nanocomposite DN hydrogels are promising candidates for biomedical applications

Attività di ricerca condotta nell'ambito del progetto Marie Curie riguardante l'analisi di adesione e proliferazione di cellule umane mesenchimali su substrati e scaffold 3D porosi in acido ialuronico chimicamente modificato e rinforzato con nanoparticelle di calcio fosfati ottenute mediante sintesi sol-gel.

The Ti6Al4V alloy is one of the most commonly used in orthopedic surgery. Mechanical property of implant contributes important biological functions for load-bearing bone tissue reconstruction. There is a significant need for design and fabrication of porous scaffold with customized mechanical properties for bone tissue engineering. In this paper, bionic design and fabrication of porous implants were studied by using finite element analysis (FEA) and 3D printing techniques. Novel porous architectures were built up with diamond lattice pore structure arraying units. With finite element analysis, the structure weak points under pressure were simulated so that the mechanical properties of the implants were optimized. Porous implants with different porosities and mechanical properties were precisely fabricated by selected laser melting (SLM), one of powder bed fusion additive manufacturing techniques. The biocompatibility and repair effect were studied by in vivo experiments. Animal results indicated that the damaged load-bearing bones were well reconstructed. New generated bones embedded and fitted into the designed porous implants. The optimized design and precisely manufactured implants are conducive to bone tissue repair and reconstruction. Keywords: Biomimetic architectures, Simulation and modeling, Ti6Al4V scaffolds, Mechanical properties, 3D printing

The discovery of new strategies to repair large segmental bone defects is currently an open challenge for worldwide clinicians. In the treatment of critical-sized bone defects, an alternative strategy to traditional bone grafting is always more frequently the use of tailor-made scaffolds modelled on the final size and shape of the implant site. Here, poly-ε-caprolactone-based composite scaffolds including poly-l-lactic acid continuous fibres and hyaluronan derivates (i.e. HYAFF11®) have been investigated for the peculiar 3D architecture characterized by interconnected macroporous networks and tunable mechanical properties. Composite scaffolds were immersed in simulated body fluid solution in order to support in vivo tissue in-growth. Scaffolds loaded with autologous cells (bone marrow stromal cells) plus platelet-rich plasma and osteoconductive protein such bone morphogenetic protein-7 were also tested to evaluate eventual enhancement in bone regeneration. The morphological and mechanical properties of poly-l-lactic acid-reinforced composite scaffolds have been studied to identify the optimal scaffold design to match the implant-site requirements of sheep metatarsal defects. Dynamic mechanical tests allowed to underline the viscoelastic response of the scaffold – resulting in elastic moduli from 2.5 to 1.3 MPa, suitable to temporarily support the structural function of damaged bone tissue. In vivo preliminary investigations in a sheep model of metatarsus shaft defect also showed the attitude of the scaffold to promote osteogenesis, preferentially in association with bone marrow stromal cell and platelet-rich plasma, even if the highest amount of mature bone was reached in the case of scaffold loaded with human bone morphogenetic protein-7 released via hydrolytic degradation of HYAFF11® phases in the implant site.

The preparation of scaffolds to facilitate the replacement of damaged tissues and organs by means of tissue engineering has been much investigated. The key properties of the biomaterials used to prepare such scaffolds include biodegradability, biocompatibility and a well-defined three-dimensional 3-Dpore network structure. In this study a poly(D,L-lactide)/nanosized hydroxyapatite (PDLLA/nano-Hap) composite resin was prepared and used to fabricate composite films and computer designed porous scaffolds by micro-stereolithography, mixing varying quantities of nano-Hap powder and a liquid photoinitiator into a photo-crosslinkable PDLLA-diacrylate resin. The influence of nano-Hap on the rheological and photochemical properties of the resins was investigated, the materials being characterized with respect to their mechanical, thermal and morphological properties after post-preparation curing. In the cured composites stiffness was observed to increase with increasing concentration of nanoparticles. A computer designed construct with a pore network based on the Schwarz architecture was fabricated by stereolithography using PDLLA/nano-Hap composite resins. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

SECOND.R.I. - Secondment for the development of Research Innovation in Biomaterial Rapid Prototyping Marie Sk?odowska-Curie Actions (MSCA) Research and Innovation Staff Exchange (RISE) H2020-MSCA-RISE-2016 GA n° 734391 - Protocollo N° 0062821/2017.

Deliverable 1.2 - SECOND.R.I. - Secondment for the development of Research Innovation in Biomaterial Rapid Prototyping Marie Sk?odowska-Curie Actions (MSCA) Research and Innovation Staff Exchange (RISE) H2020-MSCA-RISE-2016 GA n° 734391. Protocollo N° 0081455/2017

Surface topography and chemistry both play a crucial role on influencing cell response in 3D porous scaffolds in terms of osteogenesis. Inorganic materials with peculiar morphology and chemical functionalities may be proficiently used to improve scaffold properties-in the bulk and along pore surface-promoting in vitro and in vivo osseous tissue in-growth. The present study is aimed at investigating how bone regenerative properties of composite scaffolds made of poly(Ɛ-caprolactone) (PCL) can be augmented by the peculiar properties of Mg(2+) ion doped hydroxyapatite (dHA) crystals, mainly emphasizing the role of crystal shape on cell activities mediated by microstructural properties. At the first stage, the study of mechanical response by crossing experimental compression tests and theoretical simulation via empirical models, allow recognizing a significant contribution of dHA shape factor on scaffold elastic moduli variation as a function of the relative volume fraction. Secondly, the peculiar needle-like shape of dHA crystals also influences microscopic (i.e. crystallinity, adhesion forces) and macroscopic (i.e. roughness) properties with relevant effects on biological response of the composite scaffold: differential scanning calorimetry (DSC) analyses clearly indicate a reduction of crystallization heat-from 66.75 to 43.05 J g(-1)-while atomic force microscopy (AFM) ones show a significant increase of roughness-from (78.15 ± 32.71) to (136.13 ± 63.21) nm-and of pull-off forces-from 33.7% to 48.7%. Accordingly, experimental studies with MG-63 osteoblast-like cells show a more efficient in vitro secretion of alkaline phosphatase (ALP) and collagen I and a more copious in vivo formation of new bone trabeculae, thus suggesting a relevant role of dHA to support the main mechanisms involved in bone regeneration.

Purpose The stereolithography process is based on the photopolymerization through a dynamic mask generator of successive layers of photocurable resin, allowing the manufactory of accurate micro objects with high aspect ratio and curved surfaces. In the present work the stereolithography technique is applied to produce nanocomposite bioactive scaffolds from Computer Assisted Design (CAD) files. Methods Porous scaffolds are designed with computer software and built with a composite poly(D,L-lactide)/nano hydroxyapatite based resin. Triply-periodic minimal surfaces are shown to be a more versatile source of biomorphic scaffold designs and scaffolds with Double Gyroid architecture are realized and characterized from morphological, mechanical and biological point of view. Results The structures show excellent reproduction of the design and good mechanical properties. Human marrow mesenchimal cells (hMSC) are seeded onto porous PDLLA composites for 3 weeks and cultured in osteogenic medium. Presence of nano-hap seems to increase the mechanical properties without affecting the morphology of the structures. The composite Double Gyroid scaffolds exhibit good biocompatibility and confirm that nano-hap enhances the scaffold bioactive and os-teoconductive potential. Conclusion The presented technology and materials enable an accurate preparation of tissue engineering composite scaffolds with a large freedom of design, and really complex internal architectures. Results indicate that the scaffolds fulfill the basic requirements of bone tissue engineering scaffold, and have the potential to be applied in orthopedic surgery.

In order to mimic the behaviors of natural tissue, the optimal approach for designing novel biomaterials has to be inspired to nature guidelines. One of the major challenge consists in the development of well-organized structures or scaffolds with controlled porosity in terms of pore size, pore shape and interconnection degree able to guide new tissue formation during the in vivo degradation following the scaffold implantation. Scaffolds endowed with molecular cues together to a controlled degradation profile should contribute to cell proliferation and differentiation, controlled vascularization, promoting the remodeling of neo tissue through a gradual transmission of bio-chemicals and biophysical signals as performed by the extracellular matrix (ECM). Here, different polymers and composites have been investigated to design scaffolds with peculiar micro and/or nanometric morphological features in order to satisfy all these requirements: a) bioactive scaffolds, with tailored porosity and high pores interconnectivity were developed by integrating PLA fibres, Calcium Phosphates particles or Hyaff11 phases into a Poly(ε-caprolactone) (PCL) matrix by the combination of filament winding technology and phase inversion/salt leaching technique as mineralised ECM analogue for bone regeneration; b) custom made PCL/hydroxyapatite scaffolds were designed by imaging and rapid prototyping technologies for the osteochondral defect. c) Ester of Hyaluronic Acid reinforced with degradable fibres were processed by composite technology, phase inversion and salt leaching technique, to obtain scaffolds for meniscus regeneration. d) PCL and gelatin nanofibres were obtained by highly customized fibre deposition via electrospinning to guide the nerve outgrowth in nerve regeneration. All the proposed approaches offer the chance of realizing tailor-made platforms with micro/nanoscale architecture and chemical composition suitable for the regeneration of the extracellular matrix of a large variety of natural tissues (i.e, bone, menisci, osteochondral and peripheral nervous tissues).

A vinyl-terminated polycaprolactone has been developed for tissue engineering applications using a one-step synthesis and functionalization method based on ring opening polymerization (ROP) of ε-Caprolactone, with hydroxyl ethyl vinyl ether (HEVE) acting both as the initiator of ROP and as photo-curable functional group. The proposed method employs a catalyst based on aluminium, instead of the most popular Tin(II) 2-ethylhexanoate, to reduce the cytotoxicity. Following the synthesis of the vinyl-terminated polycaprolactone, its reaction with fumaryl chloride (FuCl) results in a divinyl-fumarate polycaprolactone (VPCLF). The polymers obtained were thoroughly characterized using Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC) techniques. The polymer has been successfully employed, in combination with N-vinyl pyrrolidone (NVP), to fabricate films and computer-designed porous scaffolds by micro-stereolithography (μ-SL) with gyroid and diamond architectures. Characterization of the networks indicated the influence of NVP content on the network properties. Human mesenchymal stem cells adhered and spread onto VPCLF/NVP networks showing good biological properties and no cytotoxic effect. Copyright © 2016 John WileySons, Ltd.

Surface topography and chemistry both play a crucial role on influencing cell response in three dimensional porous scaffolds in terms of osteogenesis. Inorganic materials with peculiar morphology and chemical functionalities may be proficiently used to improve scaffold properties - in the bulk and along pore surface - promoting in vitro and in vivo osseous tissue in-growth. The present study is aimed at investigating how bone regenerative properties of composite scaffolds made of poly(?-caprolactone) (PCL) can be augmented by the peculiar properties of ion doped hydroxyapatite (dHA) crystals, mainly emphasizing the role of crystal shape on cell activities mediated by microstructural properties. At the first stage, the study of mechanical response by crossing experimental compression tests and theoretical simulation via empirical models, allow recognizing a significant contribution of dHA shape factor on scaffold elastic moduli variation as a function of the relative volume fraction. Secondly, the peculiar needle-like shape of dHA crystals concurs to influence microscopic (i.e., crystallinity, adhesion forces) and macroscopic (i.e, roughness) properties with relevant effects on biological response of the composite scaffold: DSC clearly indicate a reduction of crystallization heat - from 66,75 to 43.05 J/g - while AFM analyses show a significant increase of roughness - from (78.15 ± 32.71) to (136.13 ± 63.21) nm - and of pull- off forces - from 33.7% to 48.7%. Accordingly, experimental studies with MG-63 osteoblast-like cells show a more efficient in vitro secretion of ALP and collagen I and a more copious in vivo formation of new bone trabeculae, thus suggesting a relevant role of dHA to support the main mechanisms involved in bone regeneration.

Biodegradable scaffolds are generally considered as indispensable elements for engineering living tissues as they are used as temporary templates with specific mechanical and biological properties similar to native extracellular matrix (ECM). They allow modulating cell adhesion, invasion, proliferation and differentiation, prior to the regeneration of biologically functional tissue or natural ECM. In the case of bone regeneration, a current challenge is to conceive new process strategies to fabricate composite or hybrid scaffolds able to provide three-dimensional templates and synthetic ECM environments. Here, we will describe current processing technologies used to achieve structural features mimicking the ECM on various levels and successfully emulate cell–ECM interactions in order to promote the regeneration of mineralized tissues such as bone.

Porous biodegradable polymeric scaffolds are essential for tissue ­engineering application since they should provide the adequate three-dimensional structure for cellular attachment and tissue development. In this context, recent paradigm moves towards new fabrication techniques able to develop micro- and nano-structured platforms which assure an optimal balance in terms of cell ­recognition, mass transport properties, and mechanical response to reproduce the morphological and functional features of natural tissues at the microscopic and nanoscopic level. Here, a large variety of technologies has been proposed to develop tailor-made platforms with micro/nanoscale architecture and chemical composition suitable for regenerating natural bony extracellular matrix (bECM).