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| 2. |
- Bodin, Aase Katarina, 1977, et al.
(författare)
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CELL 11-Cells like cellulose scaffolds
- 2008
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Ingår i: Abstracts of Papers of the American Chemical Society. - 0065-7727. ; 235:APR 6
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 3. |
- Bodin, Aase Katarina, 1977, et al.
(författare)
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Influence of cultivation conditions on mechanical and morphological properties of bacterial cellulose tubes
- 2007
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Ingår i: Biotechnology and Bioengineering. - : Wiley. - 0006-3592 .- 1097-0290. ; 97:2, s. 425-434
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Tidskriftsartikel (refereegranskat)abstract
- Bacterial cellulose (BC) was deposited in tubular form by fermenting Acetobacter xylinum on top of silicone tubes as an oxygenated support and by blowing different concns. of oxygen, i.e., 21% (air), 35%, 50%, and 100%. Mech. properties such as burst pressure and tensile properties were evaluated for all tubes. The burst pressure of the tubes increased with an increase in oxygen ratio and reached a top value of 880 mmHg at 100% oxygen. The Young's modulus was approx. 5 MPa for all tubes, irresp. of the oxygen ratio. The elongation to break decreased from 30% to 10-20% when the oxygen ratio was increased. The morphol. of the tubes was characterized by SEM (SEM). All tubes had an even inner side and a more porous outer side. The cross section indicated that the tubes are composed of layers and that the amt. of layers and the yield of cellulose increased with an increase in oxygen ratio. We propose that an internal vessel wall with high d. is required for the tube to sustain a certain pressure. An increase in wall thickness by an increase in oxygen ratio might explain the increasing burst pressure with increasing oxygen ratio. The fermn. method used renders it possible to produce branched tubes, tubes with unlimited length and inner diams. Endothelial cells (ECs) were grown onto the lumen of the tubes. The cells formed a confluent layer after 7 days. The tubes potential as a vascular graft is currently under investigation in a large animal model at the Center of Vascular Engineering, Sahlgrenska University Hospital, Gothenburg.
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| 4. |
- Bodin, Aase Katarina, 1977, et al.
(författare)
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Modification of nanocellulose with a xyloglucan-RGD conjugate enhances adhesion and proliferation of endothelial cells: implications for tissue engineering.
- 2007
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1526-4602 .- 1525-7797. ; 8:12, s. 3697-3704
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes a novel method for introducing the RGD cell adhesion peptide to enhance cell adhesion onto bacterial cellulose (BC). BC and cotton linters as reference were modified with xyloglucan (XG) and xyloglugan bearing a GRGDS pentapeptide. The adsorptions followed Langmuir adsorption behavior, where both XGs probably decorate the cellulose surfaces as a monolayer. The adsorption maximum of the XGs reached around 180 mg/g on BC and only about three times as much on cotton linters. The adsorption was verified with colorimetric methods. The specific surface area of BC measured with XG and XG-GRGDS was about 200 m (2)/g and was almost three times less for cotton linters, 60 m (2)/g. The difference in the amounts of XGs adsorbed might be explained by the swollen network of bacterial cellulose and a more exposed and accessible bulk as compared to cotton linters. The nanocellulose material was modified homogeneously throughout the material, as seen by the z-scan in confocal microscopy. Moreover, the modification in the water phase, in comparison with organic solvents, was clearly advantageous for preserving the morphology, as observed with SEM. The modification slightly increased the wettability, which might explain the decrease in or undetectable adsorption of adhesive protein shown by QCM-D. Initial cell studies showed that adhesion of human endothelial cells is enhanced when the BC hydrogel is modified with XG-GRGDS. QCM-D studies further revealed that the cell enhancement is due to the presence of the RGD epitope on XG and not to a nonspecific adsorption of fibronectin from cell culture medium. Optimization and proliferation studies of human endothelial cells onto bacterial cellulose modified with XG-GRGDS are currently being carried out at the Vascular Engineering Center, Sahlgrenska University Hospital, Gothenburg.
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| 5. |
- Bäckdahl, Henrik, 1977, et al.
(författare)
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Engineering microporosity in bacterial cellulose scaffolds
- 2008
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Ingår i: Journal of tissue engineering and regenerative medicine. - : Hindawi Limited. - 1932-6254 .- 1932-7005. ; 2:6, s. 320-330
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Tidskriftsartikel (refereegranskat)abstract
- The scaffold is an essential component in tissue engineering. A novel method to prepare threedimensional (3D) nanofibril network scaffolds with controlled microporosity has been developed. By placing paraffin wax and starch particles of various sizes in a growing culture of Acetobacter xylinum, bacterial cellulose scaffolds of different morphologies and interconnectivity were prepared. Paraffin particles were incorporated throughout the scaffold, while starch particles were found only in the outermost area of the resulting scaffold. The porogens were successfully removed after culture with bacteria and no residues were detected with electron spectroscopy for chemical analysis (ESCA) or Fourier transform infra-red spectroscopy (FT-IR). Resulting scaffolds were seeded with smooth muscle cells (SMCs) and investigated using histology and organ bath techniques. SMC were selected as the cell type since the main purpose of the resulting scaffolds is for tissue engineered blood vessels. SMCs attached to and proliferated on and partly into the scaffolds. Copyright © 2008 John Wiley & Sons, Ltd.
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| 6. |
- Bäckdahl, Henrik, 1977, et al.
(författare)
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Mechanical properties of bacterial cellulose and interactions with smooth muscle cells
- 2006
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Ingår i: Biomaterials. - : Elsevier BV. - 0142-9612 .- 1878-5905. ; 27:9, s. 2141-2149
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Tidskriftsartikel (refereegranskat)abstract
- Tissue engineered blood vessels (TEBV) represent an attractive approach for overcoming reconstructive problems associated with vascular diseases by providing small calibre vascular grafts. The aim of this study has been to evaluate a novel biomaterial, bacterial cellulose (BC), as a potential scaffold for TEBV. The morphology of the BC pellicle grown in static culture was investigated with SEM. Mechanical properties of BC were measured in Krebs solution and compared with the properties of porcine carotid arteries and ePTFE grafts. Attachment, proliferation and ingrowth of human smooth muscle cells (SMC) on the BC were analysed in vitro. The BC pellicle had an asymmetric structure composed of a fine network of nanofibrils similar to a collagen network. The shape of the stress-strain response of BC is reminiscent of the stress-strain response of the carotid artery, most probably due to the similarity in architecture of the nanofibrill networks. SMC adhered to and proliferated on the BC pellicle; an ingrowth of up to 40 microm was seen after 2 weeks of culture. BC exhibit attractive properties for use in future TEBV.
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| 7. |
- Bäckdahl, Henrik, 1977, et al.
(författare)
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Observations on bacterial cellulose tube formation for application as vascular graft
- 2011
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Ingår i: Materials Science and Engineering C. - : Elsevier BV. - 0928-4931 .- 1873-0191. ; 31:1, s. 14-21
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Tidskriftsartikel (refereegranskat)abstract
- Nanocellulose (bacterial cellulose, BC), such as that produced by Acetobacter xylinum, has shown promising results as a replacement material for small diameter vascular grafts. The surface morphology of the lumen and mechanical properties of such tubes are crucial for their performance. The growth of a BC tube in a vertical fermentation bioreactor using silicone tubing for support and as an oxygen delivery membrane has not been studied in detail previously. Oxygen concentration and the number of bacteria added influence the production of the BC tubes. A dense and smooth luminal surface was formed after 4 days on a 3 mm silicone support. The bacteria were found to be in high concentration close to the silicon support and decreased in number further away. In the region with a high bacteria concentration, dense thin layers of BC were formed since the bacteria moved close together in this region. The presented observations were summarized in a theoretical model of BC tube growth.
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| 8. |
- Delle, M., et al.
(författare)
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Preserved pelvic circulation after stent-graft treatment of complex aortoiliac artery aneurysms: a new approach
- 2005
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Ingår i: Journal of endovascular therapy. - 1526-6028. ; 12:2, s. 189-95
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To describe an endovascular technique that allows stent-graft treatment of aortoiliac aneurysmal disease affecting both common iliac arteries (CIA), with maintenance of pelvic circulation on one side. TECHNIQUE: For patients with aortoiliac aneurysms, both common femoral arteries (CFA) were surgically exposed. One internal iliac artery (IIA) was initially embolized with coils. A bifurcated stent-graft main body was deployed with the proximal end just below the renal arteries. On the ipsilateral side, the stent-graft limb was extended 3 cm beyond the orifice of the embolized IIA into the external iliac artery (EIA) using stent-graft limb extenders. On the contralateral side, the stent-graft limb was deployed so that the distal end was 10 to 15 mm proximal to the patent IIA orifice. Via a left brachial artery access, the IIA was catheterized, and stent-grafts were deployed from the distal end of the contralateral AAA stent-graft limb into the IIA. A femorofemoral crossover graft provided circulation to the leg ipsilateral to the IIA stent-graft, and the EIA on the same side was ligated. The technique can also be modified to treat isolated bilateral CIA aneurysms. CONCLUSIONS: By extending the distal aspect of the stent-graft into an IIA, bilateral CIA aneurysms can be excluded while preserving pelvic circulation on one side.
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| 9. |
- Eriksson, Bengt I., 1946, et al.
(författare)
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Prevention of deep-vein thrombosis and pulmonary embolism after total hip replacement. Comparison of low-molecular-weight heparin and unfractionated heparin.
- 1991
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Ingår i: The Journal of bone and joint surgery. American volume. - 0021-9355. ; 73:4, s. 484-93
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Tidskriftsartikel (refereegranskat)abstract
- In a prospective, randomized, double-blind study, the efficacy and safety of a low-molecular-weight heparin were compared with those of unfractionated sodium heparin (standard heparin) in 136 patients who had elective total hip replacement. The patients received subcutaneous injection of either 5000 international units of low-molecular-weight heparin once daily or 5000 international units of standard heparin three times a day. Treatment with low-molecular-weight heparin began twelve hours before the operation, and treatment with standard heparin began two hours preoperatively; both regimens were continued for ten days. Twelve days postoperatively, bilateral ascending phlebography was performed in 122 patients, sixty-three in the treatment group that received low-molecular-weight heparin and fifty-nine in the treatment group that received standard heparin. Pulmonary scintigraphy was performed in 127 patients. Deep-vein thrombosis was diagnosed in forty-four patients: nineteen (30 per cent) of the sixty-three who received low-molecular-weight heparin and twenty-five (42 per cent) of the fifty-nine who received standard heparin. All but four patients, two from each treatment group, were asymptomatic. The difference in the total rate of thrombosis in the two groups was not significant (p = 0.189). However, thrombosis occurred in the thigh in only six (10 per cent) of the patients who received low-molecular-weight heparin but in eighteen (31 per cent) of those who received standard heparin, a significant difference (p = 0.011). Pulmonary embolism was detected in twenty-seven patients: eight (12.3 per cent) of those who received low-molecular-weight heparin and nineteen (30.6 per cent) of those who received standard heparin. Only three patients had clinical signs of embolism. Pulmonary embolism was significantly more frequent in the group that received standard heparin (p = 0.016). Total loss of blood and the total amount of blood that was transfused were significantly reduced in the patients who received low-molecular-weight heparin compared with those who received standard heparin. Prophylaxis was not discontinued because of hemorrhage in any patient. The efficacy of low-molecular-weight heparin was superior to that of standard heparin in the prevention of femoral thrombosis and pulmonary embolism, although the over-all incidence of deep-vein thrombosis was not statistically different.(ABSTRACT TRUNCATED AT 400 WORDS)
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| 10. |
- Esguerra, Maricris, 1981, et al.
(författare)
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Intravital fluorescent microscopic evaluation of bacterial cellulose as scaffold for vascular grafts.
- 2010
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Ingår i: Journal of biomedical materials research. Part A. - : Wiley. - 1552-4965 .- 1549-3296. ; 93:1, s. 140-9
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Tidskriftsartikel (refereegranskat)abstract
- Although commonly used synthetic vascular grafts perform satisfactorily in large caliber blood vessels, they are prone to thrombosis in small diameter vessels. Therefore, small vessels might benefit from tissue engineered vascular grafts. This study evaluated bacterial cellulose (BC) as a potential biomaterial for biosynthetic blood vessels. We implanted the dorsal skinfold chambers in three groups of Syrian golden hamsters with BC (experimental group), polyglycolic acid, or expanded polytetrafluorethylene (control groups). Following implantation, we used intravital fluorescence microscopy, histology, and immunohistochemistry to analyze the biocompatibility, neovascularization, and incorporation of each material over a time period of 2 weeks. Biocompatibility was good in all groups, as indicated by the absence of leukocyte activation upon implantation. All groups displayed angiogenic response in the host tissue, but that response was highest in the polyglycolic acid group. Histology revealed vascularized granulation tissue surrounding all three biomaterials, with many proliferating cells and a lack of apoptotic cell death 2 weeks after implantation. In conclusion, BC offers good biocompatibility and material incorporation compared with commonly used materials in vascular surgery. Thus, BC represents a promising new biomaterial for tissue engineering of vascular grafts.
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