pinecone/core-2020-05-10-deduplication huggingface dataset:
Novel poly(L-lactic acid)/hyaluronic acid macroporous hybrid scaffolds : characterization and assessment of cytotoxicity

Poly(L-lactic acid), PLLA, a synthetic biodegradable polyester, is widely accepted in tissue engineering. Hyaluronic acid (HA), a natural polymer, exhibits an excellent biocompatibility, influences cell signaling, proliferation, and differentiation. In this study, HA crosslinking was performed by immersion of the polysaccharide in water-acetone mixtures containing glutaraldehyde (GA). The objective of this work is to produce PLLA scaffolds with the pores coated with HA, that could be beneficial for bone tissue engineering applications. PLLA tridimensional scaffolds were prepared by compression molding followed by salt leaching. After the scaffolds impregnation with soluble HA solutions of distinct concentration, a GA-crosslinking reaction followed by inactivation of the unreacted GA with glycine was carried out. An increase on surface roughness is shown by scanning electron microscopy (SEM) with the addition of HA. Toluidine blue staining indicates the present of stable crosslinked HA. An estimation of the HA original weight in the hybrid scaffolds was performed using thermal gravimetric analyses. FTIR-ATR and XPS confirmed the crosslinking reaction. Preliminary in vitro cell culture studies were carried out using a mouse lung fibroblast cell line (L929). SEM micrographs of L929 showed that cells adhered well, spread actively throughout all scaffolds, and grew favorably. A MTS test indicated that cells were viable when cultured onto the surface of all scaffolds, suggesting that the introduction of crosslinked HA did not increase the cytotoxicity of the hybrid scaffolds.Contract grant sponsor: Portuguese Foundation for Science and Technology (FCT) through POCTIContract grant sponsor: FEDER programs including project ProteoLight; contract grant number: PTDC/FIS/68517/2006Contract grant sponsor: European Union funded STREP Project HIPPOCRATES; contract grant number: NMP3-CT-2003-505758Contract grant sponsor: European NoE EXPERTISSUES; contract grant number: NMP3-CT-2004-500283Contract grant sponsor: Spanish Ministry of Science (The FEDER financial support); contract grant number: MAT2007-66759-C03-01The authors acknowledge the funding for research in the field of Regenerative Medicine through the collaboration agreement from the Conselleria de Sanidad (Generalitat Valenciana) and the Instituto de Salud Carlos III (Ministry of Science and Innovation). The European Union Financing, as part of the SOCRA-TES/Erasmus program is also gratefully acknowledged
Enhanced osteoblastic activity and bone regeneration using surface-modified porous bioactive glass scaffolds

The potential use as a bone substitute material of a three-dimensional bioactive glass fiber scaffold composed of Na(2)O-K(2)O-MgO-CaO-B(2)O(3)-P(2)O(5)-SiO(2) (BG1) was investigated in this work. Scaffolds were pre-treated with simulated body fluid (SBF) to promote the formation of two different bone-like apatite layers on their surfaces. The topography and roughness of the deposited layers were assessed by scanning electron microscopy (SEM), while the chemical composition and structure using X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy, respectively. Based on surface analysis, the bioactive glass surfaces were ranked from smoothest to roughest: 0 SBF (untreated), 1x SBF and 2x SBF. A calcium-deficient carbonated hydroxyapatite (HCA) layer was present on both SBF-treated scaffolds, with higher number and larger bone-like apatite nodule formation in the 2x SBF case. MC3T3-E1 preosteoblasts showed a more flattened morphology and higher cell proliferation on the nontreated scaffolds; whereas, cells were more elongated and had higher osteoblastic activity on SBF-treated samples. In vivo results in a rabbit calvarial bone defect model showed enhanced bone formation with SBF pretreated scaffolds, compared with untreated ones, commercially available Perioglass particles and empty defects. Our findings demonstrate that the formation of a rough HCA layer on bioactive glass porous scaffolds enhanced preosteoblast maturation in vitro, as well as bone formation in vivo
Combination of enzymes and flow perfusion conditions improves osteogenic differentiation of bone marrow stromal cells cultured upon starch/poly(å-caprolactone) fiber meshes

Previous studies have shown that a-amylase and
lipase are capable of enhancing the degradation of fiber
meshes blends of starch and poly(e-caprolactone) (SPCL)
under dynamic conditions, and consequently to promote the
proliferation and osteogenic differentiation of bone marrow
stromal cells (MSCs). This study investigated the effect of flow
perfusion bioreactor culture in combination with enzymes on
the osteogenic differentiation of MSCs. SPCL fiber meshes
were seeded with MSCs and cultured with osteogenic medium
supplemented with a-amylase, lipase, or a combination
of the two for 8 or 16 days using static or flow conditions.
Lipase and its combination with a-amylase enhanced cell proliferation
after 16 days. In addition, the flow perfusion culture
enhanced the infiltration of cells and facilitated greater distribution
of extracellular matrix (ECM) throughout the scaffolds
in the presence/absence of enzymes. A significant amount of
calcium was detected after 16 days in all groups cultured in
flow conditions compared with static cultures. Nevertheless,
when a-amylase and lipase were included in the flow perfusion
cultures, the calcium content was 379 6 30 lg/scaffold after
as few as 8 days. The highest calcium content (1271 6 32
lg/scaffold) was obtained for SPCL/cell constructs cultured for
16 days in the presence of lipase and flow. Furthermore, von
Kossa staining and tetracycline fluorescence of histological
sections demonstrated mineral deposition within the scaffolds
for all groups cultured for 16 days under flow. However, all
the data corroborate that lipase coupled with flow perfusion
conditions improve the osteogenic differentiation of MSCs
and enhance ECM mineralization.Contract grant sponsor: Portuguese Foundation for Science and Technology (FCT); contract grant number: SFRH/BPD/26763/2006Contract grant sponsor: European NoE EXPERTISSUES; contract grant number: NMP3-CT-2004-50028
Genipin-cross-linked collagen/chitosan biomimetic scaffolds for articular cartilage tissue engineering applications

This was the first study to use genipin to cross-link collagen and chitosan.In this study, genipin-cross-linked collagen/chitosan biodegradable porous scaffolds were prepared for articular cartilage regeneration. The influence of chitosan amount and genipin concentration on the scaffolds physicochemical properties was evaluated. The morphologies of the scaffolds were characterized by scanning electron microscope (SEM) and cross-linking degree was investigated by ninhydrin assay. Additionally, the mechanical properties of the scaffolds were assessed under dynamic compression. To study the swelling ratio and the biostability of the collagen/chitosan scaffold, in vitro tests were also carried out by immersion of the scaffolds in PBS solution or digestion in collagenase, respectively. The results showed that the morphologies of the scaffolds underwent a fiber-like to a sheet-like structural transition by increasing chitosan amount. Genipin cross-linking remarkably changed the morphologies and pore sizes of the scaffolds when chitosan amount was less than 25%. Either by increasing the chitosan ratio or performing cross-linking treatment, the swelling ratio of the scaffolds can be tailored. The ninhydrin assay demonstrated that the addition of chitosan could obviously increase the cross-linking efficiency. The degradation studies indicated that genipin cross-linking can effectively enhance the biostability of the scaffolds. The biocompatibility of the scaffolds was evaluated by culturing rabbit chondrocytes in vitro. This study demonstrated that a good viability of the chondrocytes seeded on the scaffold was achieved. The SEM analysis has revealed that the chondrocytes adhered well to the surface of the scaffolds and contacted each other. These results suggest that the genipin-cross-linked collagen/chitosan matrix may be a promising formulation for articular cartilage scaffolding.Natural Science Foundation Team Project of Guangdong. Grant Number: 4205786Guangdong Natural Science Foundation. Grant Number: 07300602National Basic Research Program of China. Grant Number: 2005CB623902State Key Program of National Natural Science of China. Grant Number: 50732003Key Projects in the National Science and Technology Pillar Program in the Eleventh Five-year Plan Period. Grant Number: 2006BA116B0
Bioactive mesopore-glass microspheres with controllable protein-delivery properties by biomimetic surface modification

Microsphere systems with the ideal properties for bone regeneration need to be bioactive, and at the same time possess the capacity for controlled protein/drug-delivery; however, the current crop of microsphere system fails to fulfill these properties. The aim of this study was to develop a novel protein-delivery system of bioactive mesoporous glass (MBG) microspheres by a biomimetic method through controlling the density of apatite on the surface of microspheres, for potential bone tissue regeneration. MBG microspheres were prepared by using the method of alginate cross-linking with Ca2+ ions. The cellular bioactivity of MBG microspheres was evaluated by investigating the proliferation and attachment of bone marrow stromal cell (BMSC). The loading efficiency and release kinetics of bovine serum albumin (BSA) on MBG microspheres were investigated after coprecipitating with biomimetic apatite in simulated body fluids (SBF). The results showed that MBG microspheres supported BMSC attachment and the Si containing ionic products from MBG microspheres stimulated BMSCs proliferation. The density of apatite on MBG microspheres increased with the length of soaking time in SBF. BSA-loading efficiency of MBG was significantly enhanced by co-precipitating with apatite. Furthermore, the loading efficiency and release kinetics of BSA could be controlled by controlling the density of apatite formed on MBG microspheres. Our results suggest that MBG microspheres are a promising protein-delivery system as a filling material for bone defect healing and regeneration
Differentiation of mesenchymal stem cells in chitosan scaffolds with double micro and macroporosity

Bone Marrow mesenchymal stem cells can be
induced to differentiate into osteoblasts to regenerate damaged
bone tissue using tissue engineering techniques. In
this study, we examine the use of chitosan scaffolds with
double pore structure prepared by an innovative method
that combines freeze gelation (that produces micropores)
and particle leaching out technique (that produces interconnected
spherical macropores) seeking to enhance the osteogenic
differentiation of goat bone marrow stromal cells
(GBMSCs). The double pore architecture of the scaffold was
characterized by scanning electron microscopy (SEM),
microcomputed tomography and confocal laser scanning microscopy. The obtained hierarchical pore structure allowed
very efficient seeding of GBMSCs that are able to occupy
the whole volume of the scaffold, showing good adhesion
and proliferation. GBMSCs were differentiated into osteoblasts
as indicated by alkaline phosphatase activity and
osteocalcin expression. The results of this study demonstrate
that chitosan scaffold may be promising biomaterial for
bone regeneration.Contract grant sponsor: Spanish Ministry of Education (including the FEDER financial support); contract grant number: MAT2007-66759-C03-01Contract grant sponsor: Science and Innovation Ministry; contract grant number: PTA2008-0943-PContract grant sponsor: Generalitat Valenciana (Grups d'investigacio Emergents); contract grant number: GV/2009/126Contract grant sponsors: VI National R&D&D&i Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program, CIBER Actions, Instituto de Salud Carlos III (European Regional Development Fund)Contract grant sponsor: FCT project; contract grant number: PTDC/QUI/68804/200
A peptidomimetic inhibitor of matrix metalloproteinases containing a tetherable linker group

Successful wound repair and normal turnover of the extracellular matrix relies on a balance between matrix metalloproteinases (MMPs) and their natural inhibitors (the TIMPs). When over-expression of MMPs and abnormally high levels of activation or low expression of TIMPs are encountered, excessive degradation of connective tissue and the formation of chronic ulcers can occur. One strategy to rebalance MMPs and TIMPs is to use inhibitors. We have designed a synthetic pseudopeptide inhibitor with an amine linker group based on a known high-affinity peptidomimetic MMP inhibitor have demonstrated inhibition of MMP-1, -2, -3 and -9 activity in standard solutions. The inhibitor was also tethered to a polyethylene glycol hydrogel using a facile reaction between the linker unit on the inhibitor and the hydrogel precursors. After tethering, we observed inhibition of the MMPs although there was an increase in the IC50s which was attributed to poor diffusion of the MMPs into the hydrogels, reduced activity of the tethered inhibitor or incomplete incorporation of the inhibitor into the hydrogels. When the tethered inhibitors were tested against chronic wound fluid we observed significant inhibition in proteolytic activity suggesting our approach may prove useful in rebalancing MMPs within chronic wounds
CaSiO3 microstructure modulating the in vitro and in vivo bioactivity of poly (lactide-co-glycolide) microspheres

Poly (lactide-co-glycolide) (PLGA) microspheres have been used for regenerative medicine due to their ability for drug delivery and generally good biocompatibility, but they lack adequate bioactivity for bone repair application. CaSiO3 (CS) has been proposed as a new class of material suitable for bone tissue repair due to its excellent bioactivity. In this study, we set out to incorporate CS into PLGA microspheres to investigate how the phase structure (amorphous and crystal) of CS influences the in vitro and in vivo bioactivity of the composite microspheres, with a view to the application for bone regeneration. X-ray diffraction (XRD), N2 adsorption-desorption analysis and scanning electron microscopy (SEM) were used to analyze the phase structure, surface area/pore volume, and microstructure of amorphous CS (aCS) and crystal CS (cCS), as well as their composite microspheres. The in vitro bioactivity of aCS and cCS – PLGA microspheres was evaluated by investigating their apatite-mineralization ability in simulated body fluids (SBF) and the viability of human bone mesenchymal stem cells (BMSCs). The in vivo bioactivity was investigated by measuring their de novo bone-formation ability. The results showed that the incorporation of both aCS and cCS enhanced the in vitro and in vivo bioactivity of PLGA microspheres. cCS/PLGA microspheres improved better in vitro BMSC viability and de novo bone-formation ability in vivo, compared to aCS/PLGA microspheres. Our study indicates that controlling the phase structure of CS is a promising method to modulate the bioactivity of polymer microsphere system for potential bone tissue regeneration
Poly(dimethyl siloxane) surface modification with biosurfactants isolated from probiotic strains

Depending on the final application envisaged for a given biomaterial, many surfaces must be modified before use. The material performance in a biological environment is mainly mediated by its surface properties that can be improved using suitable modification methods. The aim of this work was to coat poly(dimethyl siloxane) (PDMS) surfaces with biosurfactants (BSs) and to evaluate how these compounds affect the PDMS surface properties. BSs isolated from four probiotic strains (Lactococcus lactis, Lactobacillus paracasei, Streptococcus thermophilus A, and Streptococcus thermophilus B) were used. Bare PDMS and PDMS coated with BSs were characterized by contact angle measurements, infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). The influence of the surface modifications on the materials blood compatibility was studied through thrombosis and hemolysis assays. The cytotoxicity of these materials was tested against rat peritoneal macrophages. AFM results demonstrated the successful coating of the surfaces. Also, by contact angle measurements, an increase of the coated surfaces hydrophilicity was seen. Furthermore, XPS analysis indicated a decrease of the silicon content at the surface, and ATR-FTIR results showed the presence of BS characteristic groups as a consequence of the modification. All the studied materials revealed no toxicity and were found to be nonhemolytic. The proposed approach for the modification of PDMS surfaces was found to be effective and opens new possibilities for the application of these surfaces in the biomedical field.Contract grant sponsors: Portuguese Science and Technology Foundation (Fundacao para a Ciencia e Tecnologia-FCT; BIOSURFA-PTDC/SAU-BEB/73498/2006 project
Immobilized thermolysin for highly efficient production of low‐molecular‐weight protamine—An attractive cell‐penetrating peptide for macromolecular drug delivery applications

Macromolecules present a remarkable potential as future therapeutics. However, their translation into clinical practice has been hampered by an inherently low bioavailability. Cell‐penetrating peptides (CPP) have been recently shown to significantly improve on the bioavailability of macromolecules. Yet, the high cost associated with development and production of these peptides is a major factor hindering their rapid deployment beyond the laboratory. Here, we describe a facile and robust methodology for efficient and large‐scale production of low‐molecular‐weight protamine—a potent CPP of great clinical potential. Our methodology is based on the immobilization of thermolysin, an enzyme catalyzing digestion of native protamine, on chemically surface‐modified gels produced by silica sol–gel chemistry. Thermolysin was immobilized at extremely high matrix loading of 733 mg/g matrix and exhibited good thermal and pH stability, indicating robustness with respect to processing conditions. The mechanical properties of the silica matrix further allowed utilization of the immobilized thermolysin in both batch and packed‐bed reactor systems to produce the LMWP peptide in high yields. Results presented here are of high significance as this efficient and cost‐effective production of high purity LMWP could enable clinical translation of many potential macromolecular drugs. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2012
Three‐dimensional polycaprolactone scaffold‐conjugated bone morphogenetic protein‐2 promotes cartilage regeneration from primary chondrocytes  in vitro  and  in vivo  without accelerated endochondral ossification

As articular cartilage is avascular, and mature chondrocytes do not proliferate, cartilage lesions have a limited capacity for regeneration after severe damage. The treatment of such damage has been challenging due to the limited availability of autologous healthy cartilage and lengthy and expensive cell isolation and expansion procedures. Hence, the use of bone morphogenetic protein‐2 (BMP‐2), a potent regulator of chondrogenic expression, has received considerable attention in cartilage and osteochondral tissue engineering. However, the exact role of BMP‐2 in cartilage repair has been postulated to promote both cartilage formation and subsequent cartilage degradation through hypertrophy and endochondral ossification. Furthermore, it is likely that the manner in which BMP‐2 is presented to chondrocytes will influence the physiologic pathway (repair vs. degeneration). This study investigates the relative influence of BMP‐2 on cartilage matrix and potential subsequent bone matrix production using primary chondrocytes seeded on designed 3D polycaprolactone (PCL) scaffolds with chemically conjugated BMP‐2. The results show that chemically conjugated BMP‐2 PCL scaffolds can promote significantly greater cartilage regeneration from seeded chondrocytes both  in vitro  and  in vivo  compared with untreated scaffolds. Furthermore, our results demonstrate that the conjugated BMP‐2 does not particularly accelerate endochondral ossification even in a readily permissible and highly vascular  in vivo  environment compared with untreated PCL scaffolds. This study not only reveals the potential use of the BMP‐2 conjugation delivery method for enhanced cartilage tissue formation but also gives new insights for the effects of conjugated BMP‐2 on cartilage regeneration and osteochondral ossification. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2012
Gradual pore formation in natural origin scaffolds throughout subcutaneous implantation

This study used a rat subcutaneous implantation
model to investigate gradual in situ pore formation in a
self-regulating degradable chitosan-based material, which
comprises lysozyme incorporated into biomimetic calcium
phosphate (CaP) coatings at the surface to control the scaffold
degradation and subsequent pore formation. Specifically, the
in vivo degradation of the scaffolds, the in situ pore formation,
and the tissue response were investigated. Chitosan or
chitosan/starch scaffolds were studied with and without a CaP
coating in the presence or absence of lysozyme for a total of
six experimental groups. Twenty-four scaffolds per group
were implanted, and eight scaffolds were retrieved at each of
three time points (3, 6, and 12 weeks). Harvested samples were
analyzed for weight loss, microcomputed tomography, and histological analysis. All scaffolds showed pronounced weight
loss and pore formation as a function of time. The highest
weight loss was 29.8% 6 1.5%, obtained at week 12 for CaP
chitosan/starch scaffolds with lysozyme incorporated. Moreover,
all experimental groups showed a significant increase in porosity
after 12 weeks. At all time points no adverse tissue reaction
was observed, and as degradation increased, histological
analysis showed cellular ingrowth throughout the implants.
Using this innovative methodology, the ability to gradually generate
pores in situ was clearly demonstrated in vivo.Contract grant sponsor: Portuguese Foundation for Science and Technology (FCT); contract grant numbers: SFRH/BPD/66897/2009, SFRH/BPD/26763/2006, SFRH/BD/24735/2005Contract grant sponsor: European NoE EXPERTISSUES; contract grant number: NMP3-CT-2004-500283Contract grant sponsor: National Institutes of Health; contract grant number: R01 DE17441Contract grant sponsor: Baylor College of Medicine Medical Scientist Training Program; contract grant number: NIH T32 GM07330Contract grant sponsor: Rice Institute of Biosciences and Bioengineering's Biotechnology Training Grant; contract grant number: NIH T32 GM008362Contract grant sponsor: Keck Center Nanobiology Training Program of the Gulf Coast Consortia; contract grant number: 5 T90 DK070121-0