| 1. |
- Ahmed, Tamer A. E., et al.
(författare)
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Characterization and inhibition of fibrin hydrogel-degrading enzymes during development of tissue engineering scaffolds
- 2007
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Ingår i: Tissue engineering. - : Mary Ann Liebert. - 1076-3279 .- 1557-8690. ; 13:7, s. 1469-1477
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Tidskriftsartikel (refereegranskat)abstract
- The goal of articular cartilage tissue engineering is to provide cartilaginous constructs to replace abnormal cartilage. We have evaluated the chondroprogenitor clonal cell line RCJ3.1C5.18 (C5.18) as a model to guide the development of appropriate scaffolds for tissue engineering. Rapid degradation of fibrin hydrogels was observed after encapsulation of C5.18 cells. The enzymes responsible for this fibrin gel breakdown were characterized to control their activity and regulate gel stability. Western blotting, confirming zymography, revealed bands due to matrix metalloproteinases (MMP-2, MMP-3) that are secreted concomitantly with fibrin hydrogels breakdown. High plasmin activity was detected in conditioned media during hydrogel breakdown but not in the confluent cells before encapsulation. Reverse transcriptase polymerase chain reaction indicated the expression of MMP-2, -3, and -9 and plasminogen in the cells. MMP-9 was 100 times higher at day 1, whereas MMP-2 started to increase and reached its maximum level by day 7. Aprotinin, a known serine protease inhibitor, and galardin (GM6001), a potent MMP inhibitor, in combination or separately, prevented the breakdown of fibrin-C5.18 hydrogels, whereas only the combination of both promoted the accumulation of extracellular matrix. These findings suggest that plasmin and MMPs contribute independently to fibrin hydrogel breakdown, but that either enzyme can achieve extracellular matrix breakdown.
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| 2. |
- Ananta, M., et al.
(författare)
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A Novel Poly(L-Lactide-co-e-Caprolactone)-Collagen Hybrid Construct for Application in Tissue Engineering
- 2007
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Ingår i: Termis-EU Meeting Abstracts, London, UK September 4-7 2007. - : Mary Ann Liebert Inc.. ; , s. 1637-1637
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A biodegradable hybrid construct consisting of a slow degrading poly(L-lactide-co-e-caprolactone) (PLA-e-CL) knitted mesh, plastically compressed (1) between two collagen gels was fabricated and tested in vitro for tissue engineering applications. The polymer mesh was incorporated to give greater mechanical stability to the compressed collagen scaffolds. The hybrid construct was characterized for fluid (weight) loss and cell viability during compression and mechanical properties. Hybrid constructs embedded and surface layered with human dermal fibroblasts (2, Eþ5 per 5 ml) were cultured for up to one week in static culture. Quantitative and qualitative data on cell viability and proliferation were obtained. It was found that the fluid (weight) loss in plastic compression of the hybrid construct was time dependent and not weight dependent at an applied load of 240 grams. No significant cell death was observed during the plastic compression process and a homogenous cell distribution was achieved. One week of static culture showed that the cultivated hybrid construct retained its mechanical properties with no evidence of degradation, and cells inside the constructs as well as layered on top of the constructs proliferated. We found the PLA-e-CL-Collagen hybrid construct a useful three-dimensional scaffold for tissue engineering of stratified tissues and potential applications in bladder wall, blood vessels and skin are currently being explored.
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| 3. |
- Armstrong, Stephanie J., et al.
(författare)
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ECM molecules mediate both Schwann cell proliferation and activation to enhance neurite outgrowth
- 2007
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Ingår i: Tissue engineering. - : Mary Ann Liebert. - 1076-3279 .- 1557-8690. ; 13:12, s. 2863-2870
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Tidskriftsartikel (refereegranskat)abstract
- Tissue engineering using a combination of biomaterials and cells represents a new approach to nerve repair. We have investigated the effect that extracellular matrix (ECM) molecules have on Schwann cell (SC) attachment and proliferation on the nerve conduit material poly-3-hydroxybutyrate (PHB), and SC influence on neurite outgrowth in vitro. Initial SC attachment to PHB mats was unaffected by ECM molecules but proliferation increased (laminin > fibronectin > collagen). SCs seeded onto ECM-coated culture inserts suspended above a monolayer of NG108-15 cells determined the effect of released diffusible factors. The effect of direct contact between the two cell types on ECM molecules was also investigated. In both systems SCs enhanced neurite number per cell and percentage of NG108-15 cells sprouting neurites. NG108-15 cells grown in direct contact with SCs had significantly longer neurites than those exposed to diffusible factors when seeded on laminin or fibronectin. Diffusible factors released from SCs cultured on ECM molecules appear to initiate neurite outgrowth, whereas SC-neuron contact promotes neurite elongation. SC proliferation was maximal on poly-D-lysine-coated surfaces, but these cells did not influence neurite outgrowth to the levels of laminin or fibronectin. This suggests that ECM molecules enhance cell number and activate SCs to release neurite promoting factors. Addition of ECM molecules to PHB nerve conduits containing SCs is likely to provide benefits for the treatment of nerve injuries.
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| 4. |
- 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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| 8. |
- Heydarkhan-Hagvall, Sepideh, 1969, et al.
(författare)
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Production of extracellular matrix components in tissue-engineered blood vessels
- 2006
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Ingår i: Tissue engineering. - : Mary Ann Liebert Inc. - 1076-3279 .- 1557-8690. ; 12:4, s. 831-42
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Tidskriftsartikel (refereegranskat)abstract
- Morphology and compliance of tissue-engineered blood vessels (TEBV) are dependent on the culture period and production of extracellular matrix (ECM) components in order to increase the strength of the developing tissue. The aim of the present study was to evaluate the potential of TEBVs to produce an ECM similar to native arteries and veins. Human smooth muscle cells (SMC) were seeded onto the poly(glycolic acid) (PGA) scaffold and placed in bioreactors filled with DMEM supplemented with growth factors. After 6 weeks, the vessels were harvested from the bioreactors and seeded with human endothelial cells at the lumen for another 3 days. Then, the TEBVs were harvested for RNA and protein isolation for further RT-PCR and Western blot. TEBVs had a similar macroscopic appearance to that of native vessels with no visible evidence of the original PGA. Histological and immunohistochemical analyses indicated the presence of high cell density and development of a highly organized structure of ECM. After 6 weeks of culture, there were significantly lower gene expression of SMC-specific markers, such as alpha-actin, caldesmon, and vimentin, and proteoglycans, such as biglycan, decorin, and versican, and other ECM components, such as collagen I and elastin, in TEBVs, with and without pulsatile conditions, compared to that of native arteries. Gene expression of fibronectin was significantly lower in TEBVs grown during pulsatile conditions compared to that of native arteries. No difference was observed in TEBVs grown during non-pulsatile conditions. The presence of alpha-actin, collagen I, decorin, and fibronectin at protein level was demonstrated in TEBVs with and without pulsatile conditions after 6 weeks and in native veins and arteries as well. How this deviation translates into mechanical properties remains to be explored.
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