pinecone/core-2020-05-10-deduplication huggingface dataset:
Antibacterial-Nanocomposite Bone Filler Based on Silver Nanoparticles and Polysaccharides

Injectable bone fillers represent an attractive strategy for the treatment of bone defects. These injectable materials should be biocompatible, capable of supporting cell growth and possibly able to exert antibacterial effects. In this work, nanocomposite microbeads based on alginate, chitlac, hydroxyapatite and silver nanoparticles were prepared and characterized. The dried microbeads displayed a rapid swelling in contact with simulated body fluid and maintained their integrity for more than 30 days. The evaluation of silver leakage from the microbeads showed that the antibacterial metal is slowly released in saline solution, with less than 6% of silver released after 1 week. Antibacterial tests proved that the microbeads displayed bactericidal effects toward S. aureus, P. aeruginosa and S. epidermidis and were also able to damage pre-formed bacterial biofilms. On the other hand, the microbeads did not exert any cytotoxic effect towards osteoblast-like cells. After characterization of the bioactive microbeads, a possible means to embed them in a fluid medium was explored in order to obtain an injectable paste. Upon suspension of the particles in alginate solution or alginate/hyaluronic acid mixtures, a homogenous and time-stable paste was obtained. Mechanical tests enabled to quantify the extrusion forces from surgical syringes, pointing out the proper injectability of the material. This novel antibacterial bone-filler appears as a promising material for the treatment of bone defects, in particular when possible infections could compromise the bone-healing process
Control of osmotic pressure to improve cell viability in cell‐laden tissue engineering constructs

Design of tissue engineering strategies deals with the need to balance both biomaterials characteristics and techniques specificities, often resulting in cellâ  compromising processing conditions. One important factor often disregarded is the osmotic pressure to which cells are exposed. An inâ  house microfluidic system was used to prove that addition of an osmotic regulator significantly benefits the generation of viable cellâ  laden hydrogels under harsh processing conditions. Human adiposeâ  derived stem cells were resuspended in 1.5% alginate and 1% gellan gum (GG; w/v) solutions containing different concentrations (0.12 M, 0.25 M and 1.5 M) of sucrose as osmotic regulator. GG (in water) and alginate (in water or phosphateâ  buffered saline) solutions were used to vary the conditions under which cells were kept prior processing. Independently of the polymer, addition of sucrose did not affect the processing conditions or the viscosity of the solutions, except at 1.5 M. The obtained results clearly demonstrate that inclusion of 0.25 M sucrose during processing of the cellâ  laden hydrogels allowed to keep cell viability around 80%, in opposition to the 20% observed in its absence, both for GG and alginateâ  derived hydrogels prepared in water. Impressively, the level of cell viability observed with the inclusion of 0.25 M sucrose, 76% for GG and 86% for alginate, was similar to that obtained with the standard alginate solution prepared in phosphateâ  buffered saline (82%). The beneficial effect of sucrose was observed within the first 5 min of processing and was maintained for prolonged experimental setups with viability values above 50%, even after a 2â  h timeâ  frame and independently of the material.The authors would like to acknowledge the Portuguese Foundation for
Science and Technology (FCT) for personal grant SFRH/BPD/109595/
2015 under the scope of POCH, co‐funded by the European Social
Fund and national funds by MCTES. The work developed was
supported by the European Research Council (Advanced Grant No.
ERC‐2012‐AdG_20120216‐321266 for the project ComplexiTE).info:eu-repo/semantics/publishedVersio
Silk fibroin microparticles as carriers for delivery of human recombinant BMPs : physical characterization and drug release

Bone morphogenetic proteins (BMPs) are cytokines with strong ability to promote new bone
formation. Herein, we report the use of silk fibroin microparticles as carriers for the delivery
of BMP-2, BMP-9 or BMP-14. BMP-containing fibroin microparticles were prepared by a mild
methodology using dropwise addition of ethanol, exhibiting mean diameters of 2.7 ± 0.3 μm.
Encapsulation efficiencies varied between 67.9 ± 6.1 % and 97.7 ± 2.0 % depending on the type
and the amount of BMP loaded. Release kinetics showed that BMP-2, BMP-9 and BMP-14 were
released in two phases profile, with a burst release in the first two days followed by a slower
release, for a period of 14 days. The release data were best explained by Korsmeyer’s model and
the Fickian model of drug diffusion. Silk fibroin microparticles can offer a promising approach for
the sustained delivery of different BMPs in tissue engineering applications.The authors wish to acknowledge. Susana Moreira, Elsa Ribeiro and Katharina Schobitz for critical input. This work was supported by Fundacao para a Ciencia e Tecnologia (PhD grant SFRH/BD/17049/2004), project ElastM POCI/CTM/57177/2004 funded by FEDER and the Fundacao para a Ciencia e Tecnologia; Marie Curie Alea Jacta EST short-term grant (MEST-CT-2004-8104) and European STREP Project HIPPOCRATES (NMP3-CT-2003-505758). This work was carried out under the scope of the European NoE EXPERTISSUES (NMP3-CT-2004-500283)
Mesenchymal stem cells protect from acute liver injury by attenuating hepatotoxicity of liver natural killer T cells in an inducible nitric oxide synthase- and indoleamine 2,3-dioxygenase-dependent manner

The effects of mesenchymal stem cells (MSCs) on the phenotype and function of natural killer T (NKT) cells is not understood. We used concanavalin A (Con A) and α-galactosylceramide (α-GalCer)-induced liver injury to evaluate the effects of MSCs on NKT-dependent hepatotoxicity. Mouse MSCs (mMSCs) significantly reduced Con A- and α-GalCer-mediated hepatitis in C57Bl/6 mice, as demonstrated by histopathological and biochemical analysis, attenuated the influx of inflammatory [T-bet + , tumour necrosis factor-α (TNF-α), interferon-γ (IFN-γ)-producing and GATA3 + , interleukin-4 (IL-4)-producing] liver NKT cells and downregulated TNF-α, IFN-γ and IL-4 levels in the sera. The liver NKT cells cultured in vitro with mMSCs produced lower amounts of inflammatory cytokines (TNF-α, IFN-γ, IL-4) and higher amounts of immunosuppressive IL-10 upon α-GalCer stimulation. mMSC treatment attenuated expression of apoptosis-inducing ligands on liver NKT cells and suppressed the expression of pro-apoptotic genes in the livers of α-GalCer-treated mice. mMSCs reduced the cytotoxicity of liver NKT cells against hepatocytes in vitro. The presence of 1-methyl-dl-tryptophan, a specific inhibitor of indoleamine 2,3-dioxygenase (IDO), or l-N G -monomethyl arginine citrate, a specific inhibitor of inducible nitric oxide synthase (iNOS), in mMSC-conditioned medium injected into α-GalCer-treated mice, counteracted the hepatoprotective effect of mMSCs in vivo and restored pro-inflammatory cytokine production and cytotoxicity of NKT cells in vitro. Human MSCs attenuated the production of inflammatory cytokines in α-GalCer-stimulated human peripheral blood mononuclear cells in an iNOS- and IDO-dependent manner and reduced their cytotoxicity against HepG2 cells. In conclusion, MSCs protect from acute liver injury by attenuating the cytotoxicity and capacity of liver NKT cells to produce inflammatory cytokines in an iNOS- and IDO-dependent manner
Immobilization of fibronectin in chitosan substrates improves cell adhesion and proliferation

Covalent grafting of biomolecules is a strategy to improve the biocompatibility and bioactivity of
materials. However, it is critical to maintain the biological activity of the biomolecule upon its
attachment to the surface. In the present study we compared the biological properties of chitosan,
in which the surface was enriched with fibronectin (Fn), using two methodologies: chemical
immobilization, using a water-soluble carbodiimide; and simple adsorption. X-ray photoelectron
spectroscopy studies confirmed the successful immobilization of Fn onto modifiedmembranes. SaOs-
2 cells were seeded onto these surfaces to assess the biological consequences of such modifications.
The presence of Fn stimulated cell adhesion on chitosan. It was found that after 7 days of culture
in the presence of covalently attached Fn, the cells are confluent; significantly fewer cells were
detected in unmodified film and in film with adsorbed Fn. This result is consistent with the fact
that considerable desorption of Fn from chitosan takes place within 24 h in culture medium. This
study showed that Fn may be easily covalently attached onto chitosan substrates, improving the
biological performance of the material. The technique could find applications in tissue-engineering
strategies, as the surface modification of chitosan-based substrates could be carried out in more
complex geometries, such as in scaffolds or particles
Surface modification of a biodegradable composite by UV laser ablation : in vitro biological performance

Melt blends of chitosan and biodegradable aliphatic polyester have been physically and biologically
studied, presenting great potential for biomedical applications. Structurally, poly(butylene
succinate)–chitosan (PBS/Cht) composite scaffolds are covered by a thin PBS layer, preventing
the desired interaction of cells/tissues with the chitosan particules. In the present work, a
selective and controlled ablation of this skin layer was induced by UV laser processing. X-ray
photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF–SIMS)
data demonstrated an increment of chitosan components and others resulting from the laser
ablation process. The biological activity (i.e. cell viability and proliferation) on the inner regions of
the composite scaffolds is not significantly different from those of the external layer, despite the
observed differences in surface roughness (determined by interferometric optical profilometry) and
wettability (water contact angle). However, the morphology of human osteoblastic cells was found
to be considerably different in the case of laser-processed samples, since the cells tend to aggregate
in multilayer columnar structures, preferring the PBS surface and avoiding the chitosan-rich areas.
Thus, UV laser ablation can be considered a model technique for the physical surface modification
of biomaterials without detrimental effects on cellular activity.This work was partially supported by the European Union Integrated Project GENOSTEM (LSH-STREP-CT-2003-503161), the European Union Network of Excellence EXPERTISSUES (NMP3-CT-2004-500283), the Interreg III Project PROTEUS (SP1P151/03) and Xunta de Galicia (Consolidacion 2006/12). The Portuguese Foundation for Science and Technology is also acknowledged for a PhD grant to A.M. (SFRH/BD/24382/2005). The authors wish to thank C. Serra from CACTI of the University of Vigo for the XPS and ToF-SIMS measurements
Allogeneic chondrogenically differentiated human bone marrow stromal cells do not induce dendritic cell maturation

Bone marrow stromal cell (BMSC)-mediated endochondral bone formation may be a promising alternative to the current gold standards of autologous bone transplantation, in the development of novel methods for bone repair. Implantation of chondrogenically differentiated BMSCs leads to bone formation in vivo via endochondral ossification. The success of this bone formation in an allogeneic system depends upon the interaction between the implanted constructs and the host immune system. The current study investigated the effect of chondrogenically differentiated human bone marrow stromal cell (hBMSC) pellets on the maturation and function of dendritic cells (DCs) by directly coculturing bone forming chondrogenic hBMSC pellets and immature or lipopolysaccharide (LPS)-matured DCs in vitro. Allogeneic chondrogenic hBMSC pellets did not affect the expression of CD80, CD86, or HLADR on immature or LPS-matured DCs following 24, 48, or 72 hr of coculture. Furthermore, they did not induce or inhibit antigen uptake or migration of the DCs over time. IL-6 was secreted by allogeneic chondrogenic hBMSC pellets in response to LPS-matured DCs. Overall, this study has demonstrated that maturation of immature DCs was not influenced by allogeneic chondrogenic hBMSC pellets. This suggests that allogeneic chondrogenic hBMSC pellets do not stimulate immunogenic responses from DCs in vitro and are not expected to indirectly activate T cells via DCs. For this reason, allogeneic chondrogenic bone marrow stromal cell pellets are promising candidates for future tissue engineering strategies utilising allogeneic cells for bone repair
Ovine bone and marrow derived progenitor cells : isolation, characterization, and osteogenic potential

Recently, research has focused on bone marrow derived multipotent\ud
mesenchymal precursor cells (MPC) for their potential clinical use in bone\ud
engineering. Prior to clinical application, MPC-based treatment concepts need to be\ud
evaluated in preclinical, immunocompetent, large animal models. Sheep in particular\ud
are considered a valid model for orthopaedic and trauma related research. However,\ud
ovine MPC and their osteogenic potential remain poorly characterized. In the present\ud
study, ex vivo expanded MPC isolated from ovine bone marrow proliferated at a\ud
higher rate than osteoblasts (OB) derived from tibial compact bone as assessed\ud
using standard 2D culture. MPC expressed the respective phenotypic profile typical\ud
for different mesenchymal cell populations (CD14-/CD31-/CD45-\ud
/CD29+/CD44+/CD166+) and showed a multilineage differentiation potential. When\ud
compared to OB, MPC had a higher mineralization potential under standard\ud
osteogenic culture conditions and expressed typical markers such as osteocalcin,\ud
osteonectin and type I collagen at the mRNA and protein level. After 4 weeks in 3D\ud
culture, MPC constructs demonstrated higher cell density and mineralization, whilst\ud
cell viability on the scaffolds was assessed >90%. Cells displayed a spindle-like\ud
morphology and formed an interconnected network. Implanted subcutaneously into\ud
NOD/SCID mice on type I collagen coated polycaprolactone-tricalciumphosphate\ud
(mPCL-TCP) scaffolds, MPC presented a higher developmental potential than\ud
osteoblasts. In summary, this study provides a detailed in vitro characterisation of\ud
ovine MPC from a bone engineering perspective and suggests that MPC provide\ud
promising means for future bone disease related treatment applications
Tissue engineered constructs based on SPCL scaffolds cultured with goat marrow cells : functionality in femoral defects

This study aims to assess the in vivo performance of cell–scaffold constructs composed of goat marrow stromal cells (GBMCs) and SPCL (a blend of starch with polycaprolactone) fibre mesh scaffolds at different stages of development, using an autologous model. GBMCs from iliac crests
were seeded onto SPCL scaffolds and in vitro cultured for 1 and 7 days in osteogenic medium. After 1 and 7 days, the constructs were characterized for proliferation and initial osteoblastic expression by alkaline phosphatase (ALP) activity. Scanning electron microscopy analysis was performed to investigate cellularmorphology and adhesion to SPCL scaffolds. Non-critical defects (diameter 6 mm, depth 3 mm) were drilled in the posterior femurs of four adult goats from which bone marrow and serum had been collected previously. Drill defects alone and defects filled with scaffolds without cells
were used as controls. After implantation, intravital fluorescence markers, xylenol orange, calcein
green and tetracycline, were injected subcutaneously after 2, 4 and 6 weeks, respectively, for bone
formation and mineralization monitoring. Subsequently, samples were stained with L´evai–Laczk´o
for bone formation and histomorphometric analysis. GBMCs adhered and proliferated on SPCL scaffolds and an initial differentiation into pre-osteoblasts was detected by an increasing level of ALP activity with the culture time. In vivo experiments indicated that bone neoformation occurred
in all femoral defects. The results obtained provided important information about the performance of SPCL–GBMC constructs in an orthotopic goat model that enabled future studies to be designed to investigate in vivo the functionality of SPCL–GBMC constructs in more complex models, viz. critical sized defects, and to evaluate the influence of in vitro cultured autologous cells in the healing and bone regenerative process.Marcia T. Rodrigues acknowledges the Portuguese Foundation for Science and Technology (FCT) for her PhD scholarship (Grant No. SFRH/BD/30745/2006). This work was partially supported by the European Union-funded STREP Project HIPPOCRATES (Grant No. NMP3-CT-2003-505758) and was carried out under the scope of the European NoE EXPERTISSUES (Grant No. NMP3-CT-2004-500283)
In situ functionalization of wet-spun fibre meshes for bone tissue engineering

Bone tissue engineering success strongly depends on our ability to develop new materials combining osteoconductive, osteoinductive and osteogenic properties. Recent studies suggest that biomaterials incorporating silanol (SiOH) groups promote and maintain osteogenesis. The purpose of the present research work was to provide evidence that using wet-spinning technologies and a calcium silicate solution as a coagulation bath, it was possible to develop an in situ functionalization methodology to obtain 3D wet-spun fibre meshes with SiOH groups, through a simple, economic and reliable process. SPCL (blend of starch with polycaprolactone) fibre meshes were produced by wet-spinning, using a calcium silicate solution as a non-solvent and functionalized in situ with SiOH groups. In vitro tests, using goat bone marrow stromal cells (GBMSCs), showed that SPCL–Si scaffolds sustained cell viability and proliferation. Furthermore, high ALP activity and matrix production indicated that SiOH groups improve cellular functionality towards the osteoblastic phenotype. Using this methodology, and assembling several wet-spun fibre meshes, 3D meshes can be developed, aiming at designing osteoconductive/osteoinductive 3D structures capable of stimulating bone ingrowth in vivo.Fundação para a Ciência e a Tecnologia (FCT
Optimized electro- and wet-spinning techniques for the production of polymeric fibrous scaffolds loaded with bisphosphonate and hydroxyapatite

This research activity was aimed at the development of composite bioactive scaffolds made of
biodegradable three-arm branched-star poly(ε-caprolactone) (∗PCL), hydroxyapatite nanoparticles
(HNPs) and clodronate (CD), a bisphosphonate that has demonstrated efficacy in the treatment
of various bone diseases and as an anti-inflammatory drug. During the experimental work, the
processing conditions for the fabrication of fibrous meshes, by either electrospinning or wetspinning,
were optimized. Stemming from a previous research activity on electrospinning of ∗PCL,
∗PCL/HNPs 3D meshes were developed, evaluating the influence of fabrication parameters on the
fibres’ morphology. By exploiting the binding affinity of bisphosphonates for hydroxyapatite, a
methodology was set up for obtaining a physical linkage between CD and HNPs, with the aim
of having a dual bioactive system loaded into ∗PCL fibrous mats. Fibres loaded with either CD
or CD–HNP particles were thus produced and analysed by scanning electron microscopy for their
morphology and by energy dispersive X-ray spectroscopy for their elemental compositionThis work was done within the framework of the European Network of Excellence 'EXPERTISSUES', Project No. NMP3-CT-2004-500283. Professor Ramani Narayan of Michigan Biotechnology Institute and Dr Fabio Neggiani of Abiogen Pharma-Pisa are acknowledged for supplying *PCL and CD, respectively
Gellan gum-based hydrogels for intervertebral disc tissue engineering applications

Intervertebral disc (IVD) degeneration is a challenging clinical problem that urgently demands viable nucleus pulposus (NP) implant materials. The best suited biomaterial for NP regeneration has yet to be identified, but it is believed that biodegradable hydrogel-based materials are promising candidates. In this work, we have developed ionic- and photo-crosslinked methacrylated gellan gum (GG–MA) hydrogels to be used in acellular and cellular tissue-engineering strategies for the regeneration of IVDs. The physicochemical properties of the developed hydrogels were investigated by Fourier-transform infrared spectroscopy, 1H nuclear magnetic resonance and differential scanning calorimetry. The swelling ability and degradation rate of hydrogels were also analysed in phosphate-buffered saline solution at physiological pH for a period of 30 days. Additionally, the morphology and mechanical properties of the hydrogels were assessed under a scanning electron microscope and dynamic compression, respectively. An in vitro study was carried out to screen possible cytotoxicity of the gellan gum-based hydrogels by culturing rat lung fibroblasts (L929 cells) with hydrogel leachables up to 7 days. The results demonstrated that gellan gum was successfully methacrylated. We observed that the produced GG–MA hydrogels possess improved mechanical properties and lower water uptake ability and degradation rate as compared to gellan gum. This work also revealed that GG–MA hydrogels are non-cytotoxic in vitro, thus being promising biomaterials to be used in IVD tissue-engineering strategies.The authors are grateful for funds provided by the Portuguese Foundation for Science and Technology (FCT) through the POCTI and FEDER programmes, including Project ProteoLight (Grant No. PTDC/FIS/68517/2006). This work was also carried outwith the support of the European Union-funded Collaborative Project Disc Regeneration (Grant No. NMP3-LA-2008-213904)
A novel method for the isolation of subpopulations of rat adipose stem cells with different proliferation and osteogenic differentiation potentials

Bone marrow has been the elected cell source of studies published so far concerning bone and cartilage tissue-engineering approaches. Recent studies indicate that adipose tissue presents significant advantages over bone marrow as a cell source for tissue engineering. Most of these
studies report the use of adipose stem cells (ASCs) isolated by a method based on the enzymatic digestion of the adipose tissue and on the ability of stem cells to adhere to a cell culture plastic surface. Using this method, a heterogeneous population was obtained containing different cell types that have been shown to compromise the proliferation and differentiation potential of the
stem cells. This paper reports the development and optimization of a new isolation method that
enables purified cell populations to be obtained that exhibit higher osteogenic differentiation
and/or proliferation potential. This method is based on the use of immunomagnetic beads coated
with specific antibodies and it is compared with other methods described in the literature for
the selection of stem cell populations, e.g. methods based on a gradient solution and enzymatic
digestion. The results showed that the isolation method based on immunomagnetic beads allows
distinct subpopulations of rat ASCs to be isolated, showing different stem cells marker expressions
and different osteogenic differentiation potentials. Therefore, this method can be used to study
niches in ASC populations and/or also allow adipose tissue to be used as a stem cell source in a more efficient manner, increasing the potential of this cell source in future clinical applications.T. Rada thanks the EU Marie Curie Actions Alea Jacta Est for a PhD fellowship. This work was partially supported by the European Union-funded STREP Project HIPPOCRATES (Grant
No. NMP3-CT-2003-505758) and was carried out under the scope of the European NoE EXPERTISSUES (Grant No. NMP3-CT-2004-500283)