| 1. |
- Brackmann, Christian, 1973, et al.
(author)
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Coherent anti-Stokes Raman scattering microscopy of human smooth muscle cells in bioengineered tissue scaffolds
- 2011
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In: Journal of Biomedical Optics. - : SPIE - International Society for Optical Engineering. - 1083-3668 .- 1560-2281. ; 16:2
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Journal article (peer-reviewed)abstract
- The integration of living, human smooth muscle cells in biosynthesized cellulose scaffolds was monitored by nonlinear microscopy toward contractile artificial blood vessels. Combined coherent anti-Stokes Raman scattering (CARS) and second harmonic generation (SHG) microscopy was applied for studies of the cell interaction with the biopolymer network. CARS microscopy probing CH(2)-groups at 2845 cm(-1) permitted three-dimensional imaging of the cells with high contrast for lipid-rich intracellular structures. SHG microscopy visualized the fibers of the cellulose scaffold, together with a small signal obtained from the cytoplasmic myosin of the muscle cells. From the overlay images we conclude a close interaction between cells and cellulose fibers. We followed the cell migration into the three-dimensional structure, illustrating that while the cells submerge into the scaffold they extrude filopodia on top of the surface. A comparison between compact and porous scaffolds reveals a migration depth of <10 μm for the former, whereas the porous type shows cells further submerged into the cellulose. Thus, the scaffold architecture determines the degree of cell integration. We conclude that the unique ability of nonlinear microscopy to visualize the three-dimensional composition of living, soft matter makes it an ideal instrument within tissue engineering.
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| 2. |
- Bäckdahl, Henrik, 1977, et al.
(author)
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Engineering microporosity in bacterial cellulose scaffolds
- 2008
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In: Journal of tissue engineering and regenerative medicine. - : Hindawi Limited. - 1932-6254 .- 1932-7005. ; 2:6, s. 320-330
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Journal article (peer-reviewed)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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| 3. |
- Esguerra, Maricris, 1981
(author)
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Engineering tissue – Bacterial cellulose as a potential biomaterial.
- 2010
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Doctoral thesis (other academic/artistic)abstract
- Cardiovascular diseases are still the predominant cause of death among the adult population in the Western world. Diseases such as myocardial infarction and stroke are caused by occluded blood vessels, as a result of atherosclerosis. Severely occluded vessels are preferably replaced with an autologous mammary artery or saphenous vein through by-pass surgery. Autologous replacement vessels are limited since many patients lack suitable vessels due to previous operations or have blood vessels that ... merare inadequate for transplantation. Available synthetic vascular conduits function satisfactorily in large vessels. However, in small blood vessels (<6 mm), synthetic grafts are prone to thrombosis. Thus, there is a need for alternative vascular graft material of biological origin. The main aim of this Thesis was to evaluate whether bacterial cellulose (BC) can be used as a biomaterial for engineered blood vessels. For an implant to be accepted in the host, it has to be biocompatible, i.e., be well integrated into the tissue and display appropriate properties. Biocompatibility studies of BC in hamster showed that the material does not induce inflammation and that both cells and microvessels grow into the BC. Thus, BC is well accepted in the tissue. Then, microporous BC was designed to further enhance biocompatibility. Smooth muscle cells (SMCs) cultured on porous BC migrated further into the material compared to cells grown on conventional BC. However, in contrast to conventional BC, porous BC elicited an inflammatory response characterized by macrophages, lymphocytes and myofibroblasts. Taken together, these results indicate that porous BC is inferior to conventional BC with regards to biocompatibility; nevertheless, microporosity improved cellular migration of SMCs in vitro. Additionally, the presence of the non-neuronal cholinergic system was evaluated in the vascular wall of the saphenous vein and cultured venous and arterial SMCs. Components of the non-neuronal cholinergic system were found in the media of the blood vessels as well as in cultured SMCs. Its function in these cells remains to be determined. This Thesis demonstrates that BC is biocompatible since it was found to be well integrated into surrounding tissues and therefore has good potential as a biomaterial for tissue engineering.
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| 4. |
- Esguerra, Maricris, 1981, et al.
(author)
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Intravital fluorescent microscopic evaluation of bacterial cellulose as scaffold for vascular grafts.
- 2010
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In: Journal of biomedical materials research. Part A. - : Wiley. - 1552-4965 .- 1549-3296. ; 93:1, s. 140-9
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Journal article (peer-reviewed)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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| 5. |
- Helenius, Gisela, 1973, et al.
(author)
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Effect of shear stress on the expression of coagulation and fibrinolytic factors in both smooth muscle and endothelial cells in a co-culture model.
- 2008
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In: European surgical research. Europ?ische chirurgische Forschung. Recherches chirurgicales europ?ennes. - : S. Karger AG. - 1421-9921 .- 0014-312X. ; 40:4, s. 325-32
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Journal article (peer-reviewed)abstract
- Blood vessels are subjected to forces due to the flow. Endothelial cells (EC) are recipients, cross-talk with smooth muscle cells (SMC), and regulate physiology. It was hypothesized that both EC and SMC respond to shear stress, which alters the expression of factors in coagulation and fibrinolysis. METHODS: A co-culture of human saphenous vein EC (HSVEC) and human saphenous vein SMC (HSVSMC) was exposed to shear, following which the cells were separated. Gene expression of tissue factor, thrombomodulin (TM), plasminogen activator inhibitor-1 (PAI-1), tissue plasminogen activator (tPA) and urokinase plasminogen activator (uPA) were analyzed with real-time RT-PCR. Protein expression was studied with ELISA. In HSVEC, the expression of PAI-1 (x2.1), tPA (x1.8), uPA (x1.6), tissue factor (x2.5) and TM (x1.9) was upregulated after 4 h of shear compared to controls. After 24 h of shear, expression was still upregulated in tPA (x2.3) and TM (x1.6). In HSVSMC, change in expression of PAI-1 (x2.1) was present after 4 h and in uPA (x2.1), and TM (x0.4) after 24 h. Both HSVEC and HSVSMC responded to shear, which led to altered expression of coagulation and fibrinolytic factors. This indicates that SMC, and interactions between EC and SMC, are more important in the regulation of vascular wall hemostasis than earlier studies have reported.
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| 6. |
- Heydarkhan-Hagvall, Sepideh, 1969, et al.
(author)
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Production of extracellular matrix components in tissue-engineered blood vessels
- 2006
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In: Tissue engineering. - : Mary Ann Liebert Inc. - 1076-3279 .- 1557-8690. ; 12:4, s. 831-42
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Journal article (peer-reviewed)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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