Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Collagen is widely used for biomedical applications and it could represent a valid alternative scaffold material for vascular tissue engineering. In this work, reconstituted collagen films were prepared from neutralized acid-soluble solutions for subsequent haemocompatibility and cell viability performance assays. First, haemoglobin-free, thrombelastography and platelet adhesion tests were performed in order to investigate the blood contact performance. Secondly, specimens were seeded with endothelial cells and smooth muscle cells, and cell viability tests were carried out by MTT and SEM. Results show that neutralized acid-soluble type I collagen films do not enhance blood coagulation, do not alter normal viscoelastic properties of blood and slightly activate platelet adhesion and aggregation. Cell culture shows that the samples are adequate substrates to support the adhesion and proliferation of endothelial and smooth muscle cells.
 ...
PMID:Biological performances of collagen-based scaffolds for vascular tissue engineering. 1599 38

Endothelialization of biomaterials is a promising way to prevent intimal hyperplasia of small-diameter vascular grafts. The aim of this study was to design a nanofiber mesh (NFM) that facilitates viability, attachment and phenotypic maintenance of human coronary artery endothelial cells (HCAECs). Collagen-coated poly(L-lactic acid)-co-poly(epsilon-caprolactone) P(LLA-CL 70:30) NFM with a porosity of 64-67% and a fiber diameter of 470+/-130 nm was fabricated using electrospinning followed by plasma treatment and collagen coating. The structure of the NFM was observed by SEM and TEM, and mechanical property was studied by tensile test. The presence of collagen on the P(LLA-CL) NFM surface was verified by X-ray photoelectron spectroscopy (XPS) and quantified by colorimetric method. Spatial distribution of the collagen in the NFM was visualized by labelling with fluorescent probe. The collagen-coated P(LLA-CL) NFM enhanced the spreading, viability and attachment of HCAECs, and moreover, preserve HCAEC's phenotype. The P(LLA-CL) NFM is a potential material for tissue engineered vascular graft.
 ...
PMID:Fabrication of collagen-coated biodegradable polymer nanofiber mesh and its potential for endothelial cells growth. 1600 Feb 19

The paper examines the release properties of collagen gels that contain covalently bound fluorescent drug analogs. Collagen gels were prepared by fibrilogenesis. The gels were stabilized by cross linking with EDAC/NHS. SEM studies showed that increasing the cross-linking time with EDAC/NHS resulted in decreasing pore size and increasing gel density. Fluorescence spectroscopy measurements showed a clear correlation between decreasing pore size and increasing gel density, and lower release rate from the gels. Additives like chondrotitin-6-sulfate (CS) and amino acids altered the release properties of the cross-linked collagen gels. CS increased the stability of collagen gels to enzymatic degradation and non-enzymatic degradation. This was attributed to increasing gel rigidity due to carbohydrate-protein interactions. The amino acid lysine increased the stability of collagen gels which was attributed to increasing cross-linking level between the collagen fibrils and the primary amine group on the lysine side chain. The amino acid histidine decreased the stability of the gels, particularly to non-enzymatic degradation. These results correlated with increasing pore size following treatment with histidine. Our study shows, for the first time, a clear correlation between structure and release properties of collagen gels. It describes in detail the effect of additives on the structural and release properties of collagen gels. The study focused on gels that were prepared through fibrillogenesis and were therefore similar in structure to native collagen.
 ...
PMID:Structure-release rate correlation in collagen gels containing fluorescent drug analog. 1600 Feb 21

Meshes of collagen and/or elastin were successfully prepared by means of electrospinning from aqueous solutions. Flow rate, applied electric field, collecting distance and composition of the starting solutions determined the morphology of the obtained fibres. Addition of PEO (M(w)=8 x 10(6)) and NaCl was always necessary to spin continuous and homogeneous fibres. Spinning a mixture of collagen and elastin resulted in fibres in which the single components could not be distinguished by SEM. Increasing the elastin content determined an increase in fibres diameters from 220 to 600 nm. The voltage necessary for a continuous production of fibres was dependent on the composition of the starting solution, but always between 10 and 25 kV. Under these conditions, non-woven meshes could be formed and a partial orientation of the fibres constituting the mesh was obtained by using a rotating tubular mandrel as collector. Collagen/elastin (1:1) meshes were stabilized by crosslinking with N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). This treatment afforded materials with a high thermal stability (T(d)=79 degrees C) without altering their original morphology. Upon crosslinking PEO and NaCl were fully leached out. Smooth muscle cells grew as a confluent layer on top of the crosslinked meshes after 14 d of culture.
 ...
PMID:Electrospinning of collagen and elastin for tissue engineering applications. 1611 44

The effect of nanofiber surface coatings on the cell's proliferation behavior was studied. Individually collagen-coated poly(epsilon-caprolactone) (PCL) nanofibers (i.e., Collagen-r-PCL in the form of a core-shell structure) were prepared by a coaxial electrospinning technique. A roughly collagen-coated PCL nanofibrous matrix was also prepared by soaking the PCL matrix in a 10 mg/mL collagen solution overnight. These two types of coated nanofibers were then used to investigate differences in biological responses in terms of proliferation and cell morphology of human dermal fibroblasts (HDF). It was found that coatings of collagen on PCL nanofibrous matrix definitely favored cells proliferation, and the efficiency is coating means dependent. As compared to PCL, the HDF density on the Collagen-r-PCL nanofiber membrane almost increased linearly by 19.5% (2 days), 22.9% (4 days), and 31.8% (6 days). In contrast, the roughly collagen-coated PCL increased only by 5.5% (2 days), 11.0% (4 days), and 21.0% (6 days). SEM observation indicated that the Collagen-r-PCL nanofibers encouraged cell migration inside the scaffolds. These findings suggest that the Collagen-r-PCL nanofibers can be used as novel functional biomimetic nanofibers toward achieving excellent integration between cells and scaffolds for tissue engineering applications.
 ...
PMID:Characterization of the surface biocompatibility of the electrospun PCL-collagen nanofibers using fibroblasts. 1615 95

The possibility of DNA-collagen complex as a drug carrier was investigated. The interaction between DNA and silver ions was proved by CD spectra. The release property of the complex of DNA-Ag+ was measured through turbidity of PBS solution to indicate that silver ions could coordinate with base pairs of DNA, and be released slowly from the complex of DNA-Ag+. Collagen film, collagen-Ag+ film, DNA-collagen film and DNA-collagen-Ag+ film were prepared, and studied through SEM. Particles were found present in DNA-collagen-Ag+ film by SEM. These show that silver ions may be enclosed inside these particles, which led to the slow release of Ag+ to the environments. Two bacteria, Escherichia coli and Staphylococcus aureus, were used to study the antibiotic properties of the complex films. The growth of E. coli and S. aureus could be inhibited by these films. It indicates that DNA-collagen may be a good drug carrier for the drug-controlled release.
 ...
PMID:DNA-collagen complex as a carrier for Ag+ delivery. 1626 46

Constructs containing autogenous mesenchymal stem cells (MSCs) seeded in collagen gels have been used by our group to repair rabbit central patellar tendon defect injuries. Although these cell-gel composites exhibit improved repair biomechanics compared to natural healing, they can be difficult to handle at surgery and lack the necessary stiffness to resist peak in vivo forces early thereafter. MSCs are typically suspended in collagen gels around two posts in the base of a well in a specially designed silicone dish. The distance between posts is approximately the length of the tendon wound site. MSCs contract the gel around the posts prior to removal of the construct for implantation at surgery. We hypothesized that in vitro construct alignment and stiffness might be enhanced in the midregion of the longer construct where the end effects of the posts on the bulk material (St. Venant effects) could be minimized. Rabbit MSCs were seeded in purified bovine collagen gel at 0.04 M cells/mg collagen. The cell-gel mixture was pipetted into silicone dishes having two post-to-post lengths (short: 11 mm and long: 51 mm) but equivalent well widths and depths and post diameters. After 14 days of incubation, tensile stiffness and modulus of the constructs were measured using equivalent grip-to-grip lengths. Collagen fiber orientation index or OI (which measures angular dispersion of fibers) was quantified using small angle light scattering (SALS). Long constructs showed significantly lower angular dispersion vs. short constructs (OI of 41.24 degrees +/-1.57 degrees vs. 48.43 degrees +/-1.27 degrees , mean+/-SEM, p<0.001) with significantly higher linear modulus (0.064+/-0.009 MPa vs. 0.024+/-0.004 MPa, p=0.0022) and linear stiffness (0.031+/-0.005 MPa vs. 0.018+/-0.004 N/mm, mean+/-SEM, respectively, p=0.0404). We now plan to use principles of functional tissue engineering to determine if repairs containing central regions of longer MSC-collagen constructs improve defect repair biomechanics after implantation at surgery.
 ...
PMID:Effect of length of the engineered tendon construct on its structure-function relationships in culture. 1725 49

A tendon is a tough band of fibrous connective tissue that connects muscle to bone, designed to transmit forces and withstand tension during muscle contraction. Tendon may be surrounded by different structures: 1) fibrous sheaths or retinaculae; 2) reflection pulleys; 3) synovial sheaths; 4) peritendon sheaths; 5) tendon bursae. Tendons contain a) few cells, mostly represented by tenoblasts along with endothelial cells and some chondrocytes; b) proteoglycans (PGs), mainly decorin and hyaluronan, and c) collagen, mostly type I. Tendon is a good example of a high ordered extracellular matrix in which collagen molecules assemble into filamentous collagen fibrils (formed by microfibrils) which aggregate to form collagen fibers, the main structural components. It represents a multihierarchical structure as it contains collagen molecules arranged in fibrils then grouped in fibril bundles, fascicles and fiber bundles that are almost parallel to the long axis of the tendon, named as primary, secondary and tertiary bundles. Collagen fibrils in tendons show prevalently large diameter, a D-period of about 67 nm and appear built of collagen molecules lying at a slight angle (< 5 degrees). Under polarized light microscopy the collagen fiber bundles appear crimped with alternative dark and light transverse bands. In recent studies tendon crimps observed via SEM and TEM show that the single collagen fibrils suddenly changing their direction contain knots. These knots of collagen fibrils inside each tendon crimp have been termed "fibrillar crimps", and even if they show different aspects they all may fulfil the same functional role. As integral component of musculoskeletal system, the tendon acts to transmit muscle forces to the skeletal system. There is no complete understanding of the mechanisms in transmitting/absorbing tensional forces within the tendon; however it seems likely that a flattening of tendon crimps may occur at a first stage of tendon stretching. Increasing stretching, other transmission mechanisms such as an interfibrillar coupling via PGs linkages and a molecular gliding within the fibrils structure may be involved.
 ...
PMID:Collagen structure of tendon relates to function. 1745 Mar 5

Strontium is known to reduce bone resorption and stimulate bone formation. We have investigated the effect of strontium on the setting properties and in vitro bioactivity of a biomimetic gelatin-calcium phosphate bone cement. Gelatin-alpha-TCP powders, with a gelatin content of 15 wt %, were prepared by grinding and sieving the solid compounds obtained by casting gelatin aqueous solutions containing alpha-TCP. 5 wt % of CaHPO(4).2H(2)O were added to the cement powders before mixing with the liquid phase, with a L/P ratio of 0.3 mL/g. Strontium was added as SrCl(2).6H(2)O in different amounts up to 5 atom %. X-ray diffraction analysis, mechanical tests, and SEM investigations were carried out on the cements after different times of soaking in physiological solution. The presence of strontium affects both the initial and the final setting times of the cements, which increase with the ion content. The microstructural modifications observed in the SEM micrographs of the fractured surfaces are in agreement with the increase of the total porosity, and with the slight reduction of the compressive strength of the aged cements, on increasing strontium content. The rate of transformation of alpha-TCP into calcium deficient hydroxyapatite increases on increasing strontium content. SEM reveals that MG63 osteoblasts grown on the cements show a normal morphology and biological tests demonstrate very good rate of proliferation and viability in every experimental time. In particular, strontium stimulates Alkaline Phosphatase activity, Collagen type I, osteocalcin, and osteoprotegerin expression.
 ...
PMID:Setting properties and in vitro bioactivity of strontium-enriched gelatin-calcium phosphate bone cements. 1764 40

Hydrogels composed of collagen and hyaluronic acid are types of crosslinked water-swellable polymers and possess vast potential for applications in the medical industry. Collagen (Co) is the major structural protein of connective tissues such as skin, tendon and cartilage. Hyaluronic acid (HA) is a non-immunogenic, non-adhesive glycosaminoglycan that has a high water absorption property and plays significant roles in several cellular processes. The purpose of this study is to prepare a collagen (Co)-modified hyaluronic acid (MHA) hydrogel and investigate its potential utility for biomedical products such as wound dressing materials. Collagen (Co, type I) was obtained from pig skin and mucopolysaccharide-HA was modified by a poly (ethylene glycol) diglycidyl ether (PEGDGE) crosslinker. Thermal stability, swelling behavior, and mechanical strength of Co-MHA hydrogel according to different mass ratios of Co and MHA in hydrogel networks were investigated. The physical properties of the hydrogel were measured by SEM, Differential Scanning Calorimetry (DSC), Thermal Gravity Analysis (TGA), and a Universal Testing Machine (UTM). The cell viability of Co-MHA hydrogel was also evaluated using an in vitro MTT assay.
 ...
PMID:Preparation and properties of collagen/modified hyaluronic acid hydrogel for biomedical application. 1804 73


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>