| 1. |
- Ananta, M, et al.
(författare)
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A Poly(Lactic Acid-Co-Caprolactone)–Collagen Hybrid for Tissue Engineering Applications
- 2009
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Ingår i: Tissue engineering Part A. - : Mary Ann Liebert, Inc.. - 1937-3341 .- 1937-335X. ; 15:7, s. 1667-1675
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Tidskriftsartikel (refereegranskat)abstract
- A biodegradable hybrid scaffold consisting of a synthetic polymer, poly(lactic acid-co-caprolactone) (PLACL), and a naturally derived polymer, collagen, was constructed by plastic compressing hyperhydrated collagen gels onto a flat warp-knitted PLACL mesh. The collagen compaction process was characterized, and it was found that the duration, rather than the applied load under the test conditions in the plastic compression, was the determining factor of the collagen and cell density in the cell-carrying component. Cells were spatially distributed in three different setups and statically cultured for a period of 7 days. Short-term biocompatibility of the hybrid construct was quantitatively assessed with AlamarBlue and qualitatively with fluorescence staining and confocal microscopy. No significant cell death was observed after the plastic compression of the interstitial equivalents, confirming previous reports of good cell viability retention. The interstitial, epithelial, and composite tissue equivalents showed no macroscopic signs of contraction and good cell proliferation with a two- to threefold increase in cell number over 7 days. Quantitative analysis showed a homogenous cell distribution and good biocompatibility. The results indicate that viable and proliferating multilayered tissue equivalents can be engineered using the PLACL-collagen hybrid construct in the space of several hours.
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| 2. |
- Asplund, Basse, et al.
(författare)
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In vitro degradation and in vivo biocompatibility study of a new linear poly(urethane urea)
- 2008
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Ingår i: Journal of biomedical materials research. Part B: Applied biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 86B:1, s. 45-55
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Tidskriftsartikel (refereegranskat)abstract
- Segmented poly(urethane urea)s (PUUs) with hard segments derived only from methyl 2,6-diisocyantohexanoate (LDI) without the use of a chain extender have previously been described. These materials, which contain hard segments with multiple urea linkages, show exceptionally high strain capability (1600-4700%). In the study reported here, the rate and effect of hydrolysis of these materials were determined for gamma-sterilized and nonsterilized samples. Materials investigated contained PCL, PTMC, P(TMC-co-CL), P(CL-co-DLLA), or P(TMC-co-DLLA) as soft segments and, as well as their mechanical properties, changes in mass, inherent viscosity (IN.), and thermal properties were studied over 20 weeks. Results showed that the degradation rate was dependant on the soft segment structure, with a higher rate of degradation for the polyester-dominating PUUs exhibiting a substantial loss in IN. A tendency of reduction of tensile strength and strain hardening was seen for all samples. Also, loss in elongation at break was detected, for PUU-P(CL-DLLA) it went from 1600% to 830% in 10 weeks. Gamma radiation caused an initial loss in I.V. and induced more rapid hydrolysis compared with nonsterilized samples, except for PUU-PTMC. A cytotoxicity test using human fibroblasts demonstrated that the material supports cell viability. In addition, an in vivo biocompatibility study showed a typical foreign body reaction after I and 6 weeks.
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| 3. |
- Atthoff, Björn, et al.
(författare)
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Polarized protein membrane for high cell seeding efficiency
- 2007
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Ingår i: Journal of Biomedical Materials Research - Part B Applied Biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 83:2, s. 472-480
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Tidskriftsartikel (refereegranskat)abstract
- A new type of scaffold for tissue engineering was developed to give enhanced cell seeding in three dimensions. A gradient of either collagen or fibrin protein was prepared, supported by a knitted poly(ethylene terephtalate) PET fabric. The membranes were, after hydrolysis and acetic acid wash, submerged in a protein solution for adsorption followed by immersion into a gelling agent. The immediate contact between the protein solution held by the fabric and the gelling agent resulted in a dense, fibrous protein network with pore sizes around 0.5 μm at the surface, and larger pores of 10-50 μm size throughout the interior of the fabric as observed by scanning electron microscopy. By separating the fabric double layers holding this network, a gradient porosity membrane was produced. To evaluate the fractions of cells trapped in the matrix upon seeding, i.e. the seeding efficiency, 500 μl 3T3 fibroblasts cell suspension containing one million cells was seeded by filtering through the gradient protein membrane. For both the collagen and fibrin membranes, the seeding efficiency was ∼93%, which was significantly higher than that of 28% from the corresponding PET fabric without protein immobilization. Attempt to seed cells from the dense side of the protein networks resulted in no cell penetration into the scaffold. Histology on subsequent culture of the cells in the scaffold demonstrated viability and proliferation in three dimensions throughout the scaffold. This new and simple way of producing scaffolds play an important role when the cells are precious or scarce and cell seeding in three dimensions is important.
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| 4. |
- Aulin, Cecilia, et al.
(författare)
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Cell produced ECM on engineered polymer structures
- 2006
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Ingår i: Tissue Engineering and Regenerative Medicine International Society Conference, Rotterdam, 08 – 11 oktober 2006, oral presentation.
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Konferensbidrag (populärvet., debatt m.m.)
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| 5. |
- Aulin, Cecilia, et al.
(författare)
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Designing Extracellular Matrix Scaffolds by Dynamic culture of fibroblasts
- 2007
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Ingår i: TERMIS-EU Meeting Abstracts London, UK September 4–7, 2007. - : Mary Ann Liebert. ; , s. 1667-1667
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Our bodies are constantly exposed to different sorts of mechanical forces, from muscle tension to wound healing. Connective tissue adapts its extracellular matrix (ECM) to changes in mechanical load and the influence of mechanical stimulation on fibroblasts has been studied for a long time [1, 2]. When exposed to forces, fibroblasts are known to respond with expression and remodeling of ECM proteins, in particular collagen type I [3]. In this study the effect of dynamic culture conditions on human dermal fibroblasts was evaluated in terms of deposition and remodeling of ECM, with the aim of producing an ECM based scaffold. The fibroblasts were grown on compliant polymer supports either in a bioreactor with a pulsating flow or under static conditions. By applying dynamic culture conditions, the collagen deposition on the polymer supports increased fivefold. Scanning electron microscopy showed that polymer fibers were well integrated with cells and ECM and alignment along the polymer fibers was observed. Scaffold design should aim at creating structures that can help guiding the cells to form new, functional tissue. The presented system may present a new way of producing designed extracellular matrix based scaffolds for tissue engineering.
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| 6. |
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| 7. |
- Aulin, Cecilia, et al.
(författare)
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Extracellular matrix-polymer hybrid materials produced in a pulsed-flow bioreactor system
- 2009
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Ingår i: Journal of Tissue Engineering and Regenerative Medicine. - : John Wiley & Sons, Ltd. - 1932-6254 .- 1932-7005. ; 3:3, s. 188-195
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Tidskriftsartikel (refereegranskat)abstract
- Cell adhesion, interaction with material, cell proliferation and the production of an extracellular matrix (ECM) are all important factors determining the successful performance of an engineered scaffold. Scaffold design should aim at creating structures which can guide cells into forming new, functional tissue. In this study, the concept of in situ deposition of ECM by human dermal fibroblasts onto a compliant, knitted poly (ethyleneterephtalate) support is demonstrated, creating in vitro produced ECM polymer hybrid materials for tissue engineering. Comparison of cells cultured under static and dynamic conditions were examined, and the structure and morphology of the materials so formed were evaluated, along with the amount collagen deposited by the seeded cells. In vitro produced ECM polymer hybrid scaffolds could be created in this way, with the dynamic culture conditions increasing ECM deposition. Histological analysis indicated a homogenous distribution of cells in the 1 mm thick scaffold, surrounded by a matrix-like structure. ECM deposition was observed throughout the materials wigh 81.6 µg/cm2 of collagen deposited after 6 weeks. Cell produced bundles of ECM fibres bridged the polymer filaments and anchored cells to the support. These findings open hereto unknown possibilities of producing materials with structure designed by engineering together with biochemical composition given by cells.
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| 8. |
- Aulin, Cecilia, et al.
(författare)
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In vitro/ Produced Extracellular Matrix Scaffolds
- 2005
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Ingår i: European Tissue Engineering Society International Conference, München 8 Aug – 3 sept 2005, oral presentation.
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Konferensbidrag (populärvet., debatt m.m.)
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| 9. |
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| 10. |
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| 11. |
- Foroughi, Farhad, et al.
(författare)
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Bulk collagen incorporation rates into knitted stiff fibre polymer in tissue-engineered scaffolds : the rate-limiting step
- 2008
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Ingår i: Journal of Tissue Engineering and Regenerative Medicine. - : John Wiley & Sons, Ltd.. - 1932-6254 .- 1932-7005. ; 2:8, s. 507-514
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Tidskriftsartikel (refereegranskat)abstract
- Fabrication of tissue-engineered constructs in vitro relies on sufficient synthesis of extracellular matrix (ECM) by cells to form a material suitable for normal function in vivo. Collagen synthesis by human dermal fibroblasts grown in vitro on two polymers, polyethylene terephthalate (PET) and polyglycolic acid (PGA), was measured by high-performance liquid chromatography (HPLC). Cells were either cultured in a dynamic environment, where meshes were loaded onto a pulsing tube in a bioreactor, or in a static environment without pulsing. Collagen synthesis by cells cultured on a static mesh increased by six-fold compared to monolayer culture, and increased by up to a further 5.4-fold in a pulsed bioreactor. However, little of the collagen synthesized was deposited onto the meshes, almost all being lost to the medium. The amount of collagen deposited onto meshes was highest when cells were cultured dynamically on PET meshes (17.6 µg), but deposition still represented only 1.4% of the total synthesized. Although total collagen synthesis was increased by the use of 3D culture and the introduction of pulsing, the results suggest that the limiting factor for fabrication of a tissue-engineered construct within practical timescales is not the amount of collagen synthesized but the quantity retained (i.e. deposited) within the construct during culture. This may be enhanced by systems which promote or assemble true 3D multi-layers of cells.
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| 12. |
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