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 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In this work we try to develop a new thermal gelling injectable scaffold for three-dimensional cell culture. Instead of using linear, branched, or grafted macromolecules, thermosensitive microgel particles or microspheres are used as building blocks for the construction of the macroscopic hydrogel scaffold. As a proof of concept, thermosensitive poly(N-isopropylacrylamide-co-2-hydroxyethyl methacrylate) (P(NIPAM-HEMA)) microgel particles were synthesized, which present a volume phase transition temperature (VPTT) at about 29 degrees C. Rheological test shows that the concentrated P(NIPAM-HEMA) microgel dispersion is colloidally stable when heated above its VPTT, indicating hydrophobic interaction alone can not induce thermal gelation of the dispersion. In the presence of a low concentration of CaCl(2), however, with the introduction of additional ionic cross-linking, the microgel dispersion gelates and forms macroscopic hydrogel. Gelation temperature of the microgel dispersion decreases with increasing ionic strength. SEM observation reveals that the resultant bulky gel has an interconnected porous microstructure. 293T cells, a human cell line, were encapsulated inside the hydrogel by simple mixing with the microgel dispersion at room temperature and heating to 37 degrees C. MTT (3-[4,5-dimethylthiazol-2-yl]-3,5-diphenyl tetrazolium bromide) assays reveal that the cells are viable and proliferate inside the 3D scaffold.
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PMID:In situ gelation of P(NIPAM-HEMA) microgel dispersion and its applications as injectable 3D cell scaffold. 1936 98

In this study, nano-hydroxyapatite (n-HA) combined polycarbonate was synthesized by a novel method. The physical and chemical property of the composite was tested. The results indicated the n-HA a crystal has the similar grain size, phase composition and crystal structure as. TEM photos results show the n-HA crystals were uniformly distributed in the polymer matrix. Then, the chemical bond between inorganic n-HA and polycarbonate was investigated and discussed. Proliferation of MSCs/composite cultured for up to 11 days the adhesion were tested by MTT and SEM. The in vitro test confirmed that the n-HA/PC composite was biocompatible and no negative effect on MSCs has found. The composite is proved to be osteoconductive, and can stimulate the growth of new bone. These results indicated that the composite meet the basic requirement of bone substitute material, and be potentially applied for clinic.
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PMID:Development of nanohydroxyapatite/polycarbonate composite for bone repair. 1938 68

Nanofibrous scaffolds have morphological similarities to native extracellular matrix and have been considered as candidate scaffolds in tissue engineering. However, there is no report on the effect of the thickness of nanofibrous scaffold on cell behavior. In this study poly (epsilon-caprolactone) (PCL) nanofibrous scaffolds with thicknesses of 0.1 and 0.6 mm were fabricated by electrospinning. Properties of PCL nanofibrous scaffolds were measured by contact angle and air permeability measurements while the morphology of the nanofibers was observed by SEM. Mouse embryonal carcinoma stem cells (P19), monkey epithelial kidney cells (Vero), Chinese hamster ovary cells (CHO) and mouse mesenchymal stem cells (MSCs) were seeded on PCL nanofibrous scaffolds with thicknesses of 0.1 and 0.6 mm. Air permeability measurements showed that air permeability decreases with the increase in the thickness of nanofibrous scaffolds, and contact angle measurements revealed a contact angle of 118 degrees for electrospun PCL nanofibers. The MTT assays showed that the proliferation of the cells was influenced by the thickness of the nanofibrous scaffold. Scaffolds with a thickness of 0.6 mm were found to provide a better substrate for cell proliferation, possibly due to more dimensional stability. Therefore, regardless of cell origin, thicker scaffolds provide a better substrate for cell proliferation, possibly due to the higher dimensional stability and tightness of thicker scaffolds.
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PMID:The thickness of electrospun poly (epsilon-caprolactone) nanofibrous scaffolds influences cell proliferation. 1944 Sep 90

Chitosan, a deacetylated derivative of chitin is a commonly studied biomaterial for tissue-engineering applications due to its biocompatibility, biodegradability, low toxicity, antibacterial activity, wound healing ability and haemostatic properties. However, chitosan has poor mechanical strength due to which its applications in orthopedics are limited. Hydroxyapatite (HAp) is a natural inorganic component of bone and teeth and has mechanical strength and osteoconductive property. In this work, HAp was deposited on the surface of chitosan hydrogel membranes by a wet chemical synthesis method by alternatively soaking the membranes in CaCl(2) (pH 7.4) and Na(2)HPO(4) solutions for different time intervals. These chitosan hydrogel-HAp membranes were characterized using SEM, AFM, EDS, FT-IR and XRD analyses. MTT assay was done to evaluate the biocompatibility of these membranes using MG-63 osteosarcoma cells. The biocompatibility studies suggest that chitosan hydrogel-HAp composite membranes can be useful for tissue-engineering applications.
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PMID:Wet chemical synthesis of chitosan hydrogel-hydroxyapatite composite membranes for tissue engineering applications. 1944 53

In the present study, bioceramic composites with improved mechanical and biological properties were synthesized by sintering mixtures of beta-tricalcium phosphate and SiO(2)-CaO-MgO-P(2)O(5) sol-gel derived bioactive glass at 1000-1200 degrees C. The physical, mechanical, structural and biological properties of the composites were evaluated by appropriate experiments such as microhardness, bending strength, XRD, SEM and MTT. The results showed that 1000 and 1100 degrees C were not appropriate temperatures for sintering the composites and in contrast, the microhardness, bending strength and bulk density significantly increased by increasing in quantity of bioglass phase when the samples were sintered at 1200 degrees C. No significant difference was found between the fracture toughness of the composites and pure beta-tricalcium phosphate. beta-tricalcium phosphate was structurally stable up to 1200 degrees C and did not transform to its alpha form even in the presence of the bioglass phase but migration of magnesium cations from the glass composition into its lattice structure was found by right-shift in XRD patterns, especially when the composite contained higher amount of bioglass component. Calcium silicate was also crystallized in the composition of the composites, which was more detectable in higher sintering temperatures. The results of the MTT test showed that proliferation of human osteosarcoma cells on the composites was considerably better than that of pure beta-TCP.
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PMID:Composite bone substitute materials based on beta-tricalcium phosphate and magnesium-containing sol-gel derived bioactive glass. 1946 30

The quest for novel materials as scaffolds with suitable micro-architecture for supporting tissue neogenesis in tissue engineering and regenerative medicine (TERM) is continuing. In this paper we report an Antheraea assama silk-based non-woven fibroin scaffold for applications in TERM. The novel three-dimensional scaffold is highly interconnected and porous, with a pore size of 150 microm, porosity of 90% and water uptake capacity of 85%. FTIR revealed a typical beta-sheet structure of fibroin. The scaffold has thermal and mechanical properties superior to those of Bombyx mori, as revealed by DSC, TGA and tensile tests. The scaffold exhibited satisfactory blood compatibility, as determined by thrombogenicity, haemolysis, platelet/leukocyte count, platelet adhesion and protein adsorption studies. The scaffold was found to be cytocompatible with human cell lines A549, KB, HepG2 and HeLa for a period of up to 4 weeks. SEM analysis revealed excellent attachment, spreading and migration of cells in the scaffold. MTT assay was performed to estimate the viability and growth of cells in the matrix. Quantification of collagen in cell-scaffold constructs was done by picro-Sirius red assay. Ex ovo chorioallantoic membrane assay and nitric oxide estimations in spent culture medium showed the scaffold's ability to promote angiogenesis. Finally, the biodegradability of the scaffold was determined by the weight loss observed upon treatment with trypsin over a period of 4 weeks. The results reveal that the fibroin from A. assama is a promising candidate as a biocompatible, biomimetic and biodegradable biomaterial of natural origin for applications in TERM.
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PMID:Preparation and characterization of Antheraea assama silk fibroin based novel non-woven scaffold for tissue engineering applications. 1967 Mar 34

The fabrication of hydrogen bonded polymer self-assembly for drug delivery has been accomplished via layer-by-layer sequential assembly from aqueous solution. In this study, the self-assembly was constructed based on hydrogen bonding between DNA base (adenine and thymine) pairs substituted on the backbone of chitosan and hyaluronic acid. Chitosan was modified with adenine, whereas hyaluronic acid was modified with thymine. Subsequently, these two polymers were sequentially absorbed on flat substrate by taking advantage of interactions of DNA base pairs via hydrogen bonding. Interlayer hydrogen bonding of these two polymers produces stable multilayer film without using any cross-linking agent. Thin film formation on quartz substrate has been monitored with UV-vis spectra and an AFM study. Formation of multilayer hydrogen-bonded thin film has been further confirmed with SEM. Encapsulation and release behavior of the therapeutic drug from the multilayer thin film at different conditions has been illustrated using UV-vis spectra. Cell viability of modified polymers using MTT assay confirmed no cytotoxic effect.
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PMID:Layer-by-layer self-assembly of modified hyaluronic acid/chitosan based on hydrogen bonding. 1969 26

In this study, a tubular scaffold composed of polylactide fibers (outside layer) and silk fibroin-gelatin fibers (inner layer) was fabricated successfully by electrospinning. Morphological, biomechanical, and dissolvable properties of the composite scaffolds were examined, in particular, biocompatibility of the scaffolds were evaluated in vitro and in vivo by means of cell culture and subcutaneous implantation test. The PLA/SF-gelatin tubular scaffolds, with porosity of approximately 82 +/- 2%, possessed appropriate breaking strength (2.21 +/- 0.18 MPa), pliability (60.58 +/- 1.23%), and suture retention strength (4.58 +/- 0.62 N). The burst pressure strength of the composite scaffolds reached 1596 +/- 20 mmHg, which is much greater than that of the native vessels. The composite scaffolds could hardly dissolve in the water; the water-dissolved rate was only 0.3 +/- 0.1%. MTT assay and SEM observation indicated that both 3T3 mouse fibroblasts and human umbilical vein endothelial cells could adhere, spread, and proliferate well on the composite tubular scaffolds after culturing for 14 and 21 days, respectively. The subcutaneous implantation results showed that macrophages and lymphocytes were not observed, which indicated that the composite scaffolds could induce minor inflammatory reactions in vivo. The PLA/SF-gelatin tubular scaffolds are biocompatible, possess appropriate biomechanical properties, and provide a favorable environment that supports the growth of cells, which shows that the composite tube can be considered as an ideal candidate for tissue engineering blood vessel.
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PMID:Fabrication and properties of the electrospun polylactide/silk fibroin-gelatin composite tubular scaffold. 1972 59

To evaluate the cytotoxicity of PDT (photodynamic therapy) with Photogem associated to blue LED (light-emitting diode) on L929 and MDPC-23 cell cultures, 30000 cells/cm2 were seeded in 24-well plates for 48 h, incubated with Photogem (10, 25 or 50 mg/l) and irradiated with an LED source (460+/-3 nm; 22 mW/cm2) at two energy densities (25.5 or 37.5 J/cm2). Cell metabolism was evaluated by the MTT (methyltetrazolium) assay (Dunnet's post hoc tests) and cell morphology by SEM (scanning electron microscopy). Flow cytometry analysed the type of PDT-induced cell death as well and estimated intracellular production of ROS (reactive oxygen species). There was a statistically significant decrease of mitochondrial activity (90% to 97%) for all Photogem concentrations associated to blue LED, regardless of irradiation time. It was also demonstrated that the mitochondrial activity was not recovered after 12 or 24 h, characterizing irreversible cell damage. PDT-treated cells presented an altered morphology with ill-defined limits. In both cell lines, there was a predominance of necrotic cell death and the presence of Photogem or irradiation increased the intracellular levels of ROS. PDT caused severe toxic effects in normal cell culture, characterized by the reduction of the mitochondrial activity, morphological alterations and induction of necrotic cell death.
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PMID:Photodynamic therapy associating Photogem and blue LED on L929 and MDPC-23 cell culture. 1994 13

An electrochemically controlled system has been developed which allows for cell culture directly on electrically polarized metal surfaces with simultaneous control and assessment of the electrochemical current, potential, and impedance of the interface. This system was utilized in this study to assess the interactions between electrochemically polarized commercially pure titanium (cpTi) and MC3T3 preosteoblast cells. Cells were cultured on CpTi for 24 h at static potentials between -1000 mV and +1000 mV vs. Ag/AgCl and cell morphology (SEM and cell area) and viability (MTT and Live-Dead assay) were assessed along with the electrochemical current densities and surface oxide impedance properties. The results indicate that cathodic polarization in the range of -600 mV to -1000 mV markedly reduces the spreading and viability of cells cultured directly on cpTi within 24 h, while anodic polarization (-300 mV to +1000 mV) out to 72 h shows no difference in cell behavior as compared to the OCP condition. Analysis of the relationship between the cell outcomes and the electrochemical current densities and impedance indicated the presence of voltage-dependent electrochemical thresholds (cathodic current density, i(c) > 1.0 microA/cm(2), R(p) < 10(5) Omega cm(2)) which may control the biocompatibility of cpTi. In addition, these outcomes have direct clinical significance for modular orthopedic implants whose potential can shift, via fretting corrosion, down into the range of potentials exhibiting poor cell behavior.
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PMID:Titanium is not "the most biocompatible metal" under cathodic potential: The relationship between voltage and MC3T3 preosteoblast behavior on electrically polarized cpTi surfaces. 2001 93


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