| 1. |
- 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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| 2. |
- 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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| 3. |
- 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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| 4. |
- Gelin, Kristina, et al.
(författare)
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Characterization of water in bacterial cellulose using dielectric spectroscopy and electron microscopy
- 2007
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Ingår i: Polymer. - : Elsevier BV. - 0032-3861 .- 1873-2291. ; 48:26, s. 7623-7631
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Tidskriftsartikel (refereegranskat)abstract
- It is shown that only 10% of the 99 wt% water present in bacterial cellulose (BC) gels, produced by Acetobacter xylinum, behave like free bulk water; the majority of the water molecules in the gels is more or less tightly bound to the cellulose. The magnitude of the diffusion coefficients of ions transported in the water phase of the BC gels as well as the information contained in freeze fracture transmission electron microscopic images of the gel structures indicates that the bulk-like water is confined in “lakes” rather than forming a continuous phase throughout the gel. Water desorption isotherms suggest that these “lakes” decrease in size with increasing oxygen concentration used during the biosynthesis process of the gels.
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| 5. |
- Helenius, Gisela, 1973, et al.
(författare)
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In vivo biocompatibility of bacterial cellulose
- 2006
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Ingår i: Journal of biomedical materials research. - : Wiley. - 1549-3296 .- 1552-4965. ; 76:2, s. 431-8
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Tidskriftsartikel (refereegranskat)abstract
- The biocompatibility of a scaffold for tissue engineered constructs is essential for the outcome. Bacterial cellulose (BC) consists of completely pure cellulose nanofibrils synthesized by Acetobacter xylinum. BC has high mechanical strength and can be shaped into three-dimensional structures. Cellulose-based materials induce negligible foreign body and inflammatory responses and are considered as biocompatible. The in vivo biocompatibility of BC has never been evaluated systematically. Thus, in the development of tissue engineered constructs with a BC scaffold, it is necessary to evaluate the in vivo biocompatibility. BC was implanted subcutaneously in rats for 1, 4, and 12 weeks. The implants were evaluated in aspects of chronic inflammation, foreign body responses, cell ingrowth, and angiogenesis, using histology, immunohistochemistry, and electron microscopy. There were no macroscopic signs of inflammation around the implants. There were no microscopic signs of inflammation either (i.e., a high number of small cells around the implants or the blood vessels). No fibrotic capsule or giant cells were present. Fibroblasts infiltrated BC, which was well integrated into the host tissue, and did not elicit any chronic inflammatory reactions. The biocompatibility of BC is good and the material has potential to be used as a scaffold in tissue engineering.
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| 6. |
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| 7. |
- Malm, Carl Johan, et al.
(författare)
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Small calibre biosynthetic bacterial cellulose blood vessels: 13-months patency in a sheep model.
- 2012
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Ingår i: Scandinavian Cardiovascular Journal. - : Informa UK Limited. - 1651-2006 .- 1401-7431. ; 46:1, s. 57-62
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Objectives. Many patients in need of bypass surgery lack graft material and current synthetic alternatives have poor performance. A 4 mm vascular graft composed of bacterial cellulose (BC) was developed and tested in pilot study in a large animal model. Design. BC is a biopolymer made by the bacteria acetobacter xylinum. BC grafts (n = 16) with 4 cm length and 4 mm internal diameter were implanted bilaterally in the carotid arteries of eight sheep. No long-term antithrombotic therapy was administered. Patency was assessed with ultrasound. Histology, immunohistochemistry, and electron microscopy were performed after explantation. Results. Fifty percent of the grafts occluded within two weeks. One animal died with patent grafts after 14 days. In the three remaining animals 5/6 grafts were patent after nine months. Two animals were followed 13 months after implantation with 3/4 grafts patent at explantation. All patent grafts had confluent endothelial-like cells. Conclusions. Biosynthetic small calibre vascular grafts made from BC can be patent for up to 13 months in sheep carotid arteries. BC is a potential material for small calibre grafts but patency in animal models needs to be improved before clinical studies can be planned.
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| 8. |
- Zaborowska, Magdalena, 1984, et al.
(författare)
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Microporous bacterial cellulose as a potential scaffold for bone regeneration
- 2010
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Ingår i: Acta Biomaterialia. - : Elsevier BV. - 1878-7568 .- 1742-7061. ; 6:7, s. 2540-2547
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Tidskriftsartikel (refereegranskat)abstract
- Nanoporous cellulose biosynthesized by bacteria is an attractive biomaterial scaffold for tissue engineering due to its biocompatibility and good mechanical properties. However, for bone applications a microscopic pore structure is needed to facilitate osteoblast ingrowth and formation of a mineralized tissue. Therefore, in this study microporous bacterial cellulose (BC) scaffolds were prepared by incorporating 300-500 mu m paraffin wax microspheres into the fermentation process. The paraffin wax microspheres were subsequently removed, and scanning electron microscopy confirmed a microporous surface of the scaffolds while Fourier transform infrared spectroscopy verified the elimination of paraffin and tensile measurements showed a Young's modulus of approximately 1.6 MPa. Microporous BC and nanoporous (control) BC scaffolds were seeded with MC3T3-E1 osteoprogenitor cells, and examined by confocal microscopy and histology for cell distribution and mineral deposition. Cells clustered within the pores of microporous BC, and formed denser mineral deposits than cells grown on control BC surfaces. This work shows that microporous BC is a promising biomaterial for bone tissue engineering applications. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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| 9. |
- Bodin, Aase Katarina, 1977, et al.
(författare)
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Bacterial cellulose as a potential meniscus implant
- 2007
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Ingår i: Journal of tissue engineering and regenerative medicine. - : Hindawi Limited. - 1932-6254 .- 1932-7005. ; 1:5, s. 406-8
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Tidskriftsartikel (refereegranskat)abstract
- Traumatic or degenerative meniscal lesions are a frequent problem. The meniscus cannot regenerate after resection. These lesions often progress and lead to osteoarthritis. Collagen meniscal implants have been used in clinical practice to regenerate meniscal tissue after partial meniscectomy. The mechanical properties of bacterial cellulose (BC) gel were compared with a collagen material and the pig meniscus. BC was grown statically in corn steep liquid medium, as described elsewhere. Pig meniscus was harvested from pigs. The collagen implant was packed in sterile conditions until use. The different materials were evaluated under tensile and compression load, using an Instron 5542 with a 500 N load cell. The feasibility for implantation was explored using a pig model. The Young's modulus of bacterial cellulose was measured to be 1 MPa, 100 times less for the collagen material, 0.01 MPa in tensile load. The Young's modulus of bacterial cellulose and meniscus are similar in magnitude under a compression load of 2 kPa and with five times better mechanical properties than the collagen material. At higher compression strain, however, the pig meniscus is clearly stronger. These differences are clearly due to a more ordered and arranged structure of the collagen fibrils in the meniscus. The combination of the facts that BC is inexpensive, can be produced in a meniscus shape, and promotes cell migration makes it an attractive material for consideration as a meniscus implant. Copyright (c) 2007 John Wiley & Sons, Ltd.
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| 10. |
- Bodin, Aase Katarina, 1977
(författare)
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Biomedical Applications of Bacterial Cellulose Fermentation, Morphology and Surface Properties
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Because average life expectancy has increased and peoples lifestyles have changed, degenerative diseases have become a critical issue. The demand for biomedical materials to replace or improve major body systems (skeletal, circulatory and nervous, etc.) will increase as people strive to maintain good quality of life. Cellulose is the most abundant naturally occurring polymer and is an inexhaustible resource for raw materials. Bacterial cellulose (BC) resembles human tissue in the sense that it is soft and is composed of highly hydrated nano fibrils with high mechanical strength. The material is versatile and can be manufactured in various sizes and shapes depending on the product requirements. This makes it interesting to explore BC for use in several biomedical applications.In this work bacterial cellulose was fermented into tubular and meniscus form. The material properties were evaluated with a focus on mechanical, morphological and surface properties for applications such as blood vessels and meniscus substitutes. Bacterial cellulose tubes with asymmetric morphology and an onion like multilayer structure were produced by optimizing the oxygen ratio during fermentation. The inner lumen of the tube was smooth and promoted the adhesion and formation of a confluent layer of endothelial cells. The outer layer was more open, to allow cell ingrowth. The mechanical properties were improved by an increase in the oxygen ratio. A maximal burst pressure value of 880mmHg was recorded for tubes produced at 100% oxygen ratio, which is far higher than physiological blood pressure. The material was proven to be biocompatible, subcutaneous in rats. There were no foreign body reactions or encapsulation of the material. Instead newly formed blood vessels could be seen as well as ingrowth of cells and production of tissue in the material. Modification of the cellulose with xyloglucan bearing an adhesion peptide improved the adhesion of endothelial cells with an unaffected morphology of the cellulose network. The nano fibrils were also surface modified with ionic groups and decorated with calcium phosphate to improve bone adhesion and later fixation of the material as a future meniscus substitute. Initial mechanical properties of BC in compression and tensile load revealed that BC has advantageous mechanical properties compared to collagen material and has the same Youngs modulus in compression load as a pig meniscus. This research contributes to knowledge of tubular fermentation and the mechanical, morphological properties thereof and has developed two novel surface modifications to improve cell adhesion to the nano cellulose. The results can be used as a starting point for new optimization and developments of new generations of cardiovascular and orthopaedic implants using microbially derived cellulose.
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