| Autologous small-caliber "Biotube" vascular grafts with argatroban loading: A histomorphological examination after implantation to rabbits.
November 19, 2009 at 10:35 am
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| | Autologous small-caliber "Biotube" vascular grafts with argatroban loading: A histomorphological examination after implantation to rabbits. J Biomed Mater Res B Appl Biomater. 2009 Nov 17; Authors: Watanabe T, Kanda K, Ishibashi-Ueda H, Yaku H, Nakayama Y Functional autologous tubular tissues, termed "biotubes," have been developed as small-caliber vascular grafts. Biotubes can be easily and safely constructed in vivo by using a novel concept in regenerative medicine-in body tissue architecture technology, which requires neither clean specialized laboratories nor complex cell management. Biotubes with "anastomotic reinforcement cuffs" were prepared by embedding a silicone rod (diameter, 3 mm; length, 30 mm) as a mold in the dorsal subcutaneous pouches of rabbits. The rod was covered at both ends with 2 pieces of polyurethane sponge tubes (length, 3 mm), and it was removed when the grafts were harvested. These biotubes had homogeneous thin connective tissue walls (thickness: 76 +/- 37 mum) that were primarily composed of collagen and fibroblasts. The resulting cuff-impregnated biotubes were auto-implanted in the carotid arteries for predetermined periods of up to 12 weeks and then morphologically examined. On implantation of the biotubes after argatroban loading, the total patency was 9/11 without any instance of aneurysm formation or rupture. At 12 weeks after implantation, no significant neointimal thickening was observed (170 +/- 30 mum). In addition, minimal thrombus formation was observed on the luminal surfaces, which were completely covered with endothelial cells regularly oriented longitudinally. The regenerated vascular walls comprised multilayered smooth muscle cells and dense collagen fibers with regular circumferential orientation with few elastin fibers and were similar to native arteries. Biotubes with argatroban loading could thus be used as small-caliber vascular prostheses that greatly facilitate healing process and exhibit excellent biocompatibility. (c) 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010. PMID: 19921747 [PubMed - as supplied by publisher] |
| Fluorine-containing nanoemulsions for MRI cell tracking.
November 19, 2009 at 10:35 am
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| | Fluorine-containing nanoemulsions for MRI cell tracking. Wiley Interdiscip Rev Nanomed Nanobiotechnol. 2009 Sep 1;1(5):492-501 Authors: Janjic JM, Ahrens ET In this article we review the chemistry and nanoemulsion formulation of perfluorocarbons used for in vivo(19)F MRI cell tracking. In this application, cells of interest are labeled in culture using a perfluorocarbon nanoemulsion. Labeled cells are introduced into a subject and tracked using (19)F MRI or NMR spectroscopy. In the same imaging session, a high-resolution, conventional ((1)H) image can be used to place the (19)F-labeled cells into anatomical context. Perfluorocarbon-based (19)F cell tracking is a useful technology because of the high specificity for labeled cells, ability to quantify cell accumulations, and biocompatibility. This technology can be widely applied to studies of inflammation, cellular regenerative medicine, and immunotherapy. PMID: 19920872 [PubMed - as supplied by publisher] |
| Endothelial cells influence the osteogenic potential of bone marrow stromal cells.
November 19, 2009 at 10:35 am
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| | Endothelial cells influence the osteogenic potential of bone marrow stromal cells. Biomed Eng Online. 2009 Nov 17;8(1):34 Authors: Xue Y, Xing Z, Hellem S, Arvidson K, Mustafa K ABSTRACT: BACKGROUND: Improved understanding of the interactions between bone cells and endothelial cells involved in osteogenesis should aid the development of new strategies for bone tissue engineering. The aim of the present study was to determine whether direct communication between bone marrow stromal cells (MSC) and human umbilical vein endothelial cells (EC) could influence the osteogenic potential of MSC in osteogenic factor-free medium. METHODS: After adding EC to MSC in a direct-contact system, cell viability and morphology were investigated with the WST assay and immnostaining. The effects on osteogenic differentiation of adding EC to MSC was systematically tested by the using Superarray assay and results were confirmed with real-time PCR. RESULTS: Five days after the addition of EC to MSC in a ratio of 1:5 (EC/MSC) significant increases in cell proliferation and cellular bridges between the two cell types were detected, as well as increased mRNA expression of alkaline phosphatase (ALP). This effect was greater than that seen with addition of osteogenic factors such as dexamethasone, ascorbic acid and beta-glycerophosphate to the culture medium. The expression of transcription factor Runx2 was enhanced in MSC incubated with osteogenic stimulatory medium, but was not influenced by induction with EC. The expression of Collagen type I was not influenced by EC but the cells grown in the osteogenic factor-free medium exhibited higher expression than those cultured with osteogenic stimulatory medium. CONCLUSION: These results show that co-culturing of EC and MSC for 5 days influences osteogenic differentiation of MSC, an effect that might be independent of Runx2, and enhances the production of ALP by MSC. PMID: 19919705 [PubMed - as supplied by publisher] |
| Physical Hydrogels Photo-Cross-Linked from Self-Assembled Macromers for Potential Use in Tissue Engineering.
November 19, 2009 at 10:35 am
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| | Physical Hydrogels Photo-Cross-Linked from Self-Assembled Macromers for Potential Use in Tissue Engineering. Biomacromolecules. 2009 Nov 17; Authors: Liu B, Lewis AK, Shen W To engineer artificial extracellular matrices (ECMs) enabling degradation-independent cell migration that mimicked nonproteolytic cell migration through physically stabilized ECMs in biological systems, polymers having a hydrophilic chain flanked by a terminal self-assembling leucine zipper domain and a terminal photoreactive acrylate group were molecularly engineered to form photo-cross-linkable physical hydrogels. Physical association of the leucine zippers resulted in multifunctional macromers, which were photo-cross-linkable into hydrogels. Gel formation was confirmed by rheological measurements. The physical nature of the hydrogel networks was shown by hydrogel disassembly in denaturing solutions that disrupted the secondary structure of the leucine zippers. Outgrowth of encapsulated fibroblast aggregates was observed in these physical hydrogels but not observed in a control hydrogel in which leucine zippers were covalently linked. The collective properties of these hydrogels, including the physical nature, the photo-cross-linkable characteristic, and the flexibility for systematic engineering of material properties, will provide unique opportunities for tissue engineering. PMID: 19919071 [PubMed - as supplied by publisher] |
| Injectable, Highly Flexible, and Thermosensitive Hydrogels Capable of Delivering Superoxide Dismutase.
November 19, 2009 at 10:35 am
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| | Injectable, Highly Flexible, and Thermosensitive Hydrogels Capable of Delivering Superoxide Dismutase. Biomacromolecules. 2009 Nov 17; Authors: Li Z, Wang F, Roy S, Sen CK, Guan J Injectable hydrogels are attractive for cell and drug delivery. In this work, we synthesized a family of injectable, biodegradable, fast gelling and thermosensitive hydrogels based on N-isopropylacrylamide (NIPAAm), acrylic acid (AAc), dimethyl-gamma-butyrolactone acrylate (DBA), and 2-hydroxyethyl methacrylate-poly(trimethylene carbontate) (HEMAPTMC) macromer. Type I collagen was composited with the hydrogels to improve their biocompatibility. The hydrogel copolymer solutions were readily injectable at 4 degrees C. The solutions exhibited thermal transition temperatures ranging from 23.6 to 24.5 degrees C and were capable of gelation within 7 s at 37 degrees C to form highly flexible and soft hydrogels with moduli from 39 to 119 KPa and breaking strains >1000%, depending on the copolymer composition and collagen addition. After 2 weeks incubation in PBS, the hydrogels demonstrated weight losses ranging from 10-20%. The completely degraded hydrogels had thermal transition temperatures >40 degrees C and were soluble at body temperature. Superoxide dismutase (SOD) was encapsulated in the hydrogels for the purpose of capturing superoxide within the inflammatory tissue after being delivered in vivo. The hydrogels demonstrated a sustained release profile during a 21-day release period. The release kinetics was dependent on the SOD loading, collagen addition, hydrogel degradation and water content. The released SOD remained bioactive during the entire release period. To test in vitro if the loaded SOD could protect cells encapsulated within the hydrogel from attack by superoxide, human mesenchymal stem cells (MSC) were encapsulated in SOD-loaded hydrogels and cultured in medium containing superoxide generated by activated macrophages. It was found that SOD loading largely suppressed superoxide penetration into the hydrogel and cell membrane. Under normal culture conditions, SOD loading stimulated MSC growth. The SOD-loaded hydrogel exhibited significantly higher cell numbers than the non-SOD loaded hydrogel during a 7-day culture period. These results demonstrated that the developed hydrogels could be used as delivery vehicles for stem cell therapy and drug delivery. PMID: 19919046 [PubMed - as supplied by publisher] | | | 
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