| 1. |
- Myllymaa, Sami, et al.
(författare)
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Surface characterization and in vitro biocompatibility assessment of photosensitive polyimide films.
- 2010
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Ingår i: Colloids and Surfaces B. - : Elsevier. - 0927-7765 .- 1873-4367. ; 76:2, s. 505-511
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Tidskriftsartikel (refereegranskat)abstract
- Polyimide (PI) is a commonly used polymer in microelectronics. Recently, numerous PI-based flexible neural interfaces have been developed for reducing mechanical mismatch between rigid implant and soft neural tissue. Most approaches employ non-photosensitive PI, which has been proven earlier to be biocompatible. However, photosensitive polyimide (PSPI) would simplify device fabrication remarkably, but its biocompatibility has been only sparsely reported. In this study, cytotoxicity of spin-coated PSPI (HD Microsystems PI-2771) and conventional PI (HD Microsystems PI-2525) films were evaluated in vitro using BHK-21 fibroblasts according to the ISO-10993-5 standard. PSPIs were tested as cured at a temperature of 200 degrees C (PI-2771-200) and 350 degrees C (PI-2771-350). The PI film surfaces were characterized in terms of their roughness, energy and zeta potential which are hypothesized to affect cell-material interactions. The values of the total surface free energy (SFE), and its polar and dispersive component, were significantly (p<0.001) greater for the PI-2525 film (SFE: 47.3 mJ/m2) than for the PI-2771-200 (25.6 mJ/m2) or PI-2771-350 films (26.2 mJ/m2). The curing temperature of the PI-2771 had a significant effect on the zeta potential values (p<0.001), but not on surface energy (p=0.091) or roughness (p=0.717). The results from the MTS proliferation assays and live/dead staining revealed that PSPI is almost as non-cytotoxic as conventional PI and polyethylene (negative control). The morphology and spreading of BHK-21 cells were similar on all the PI materials tested. In conclusion, PSPI seems to be a promising biocompatible material, while further studies in vitro and in vivo are needed to clarify the long-term effects.
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| 2. |
- Pulkkinen, Hertta, et al.
(författare)
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Engineering of cartilage in recombinant human type II collagen gel in nude mouse model in vivo.
- 2010
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Ingår i: Osteoarthritis and Cartilage. - : Elsevier BV. - 1063-4584 .- 1522-9653. ; 18:8, s. 1077-1087
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Our goal was to test the recombinant human type II collagen (rhCII) material as a gel-like scaffold for chondrocytes in a nude mouse model in vivo.DESIGN: Isolated bovine chondrocytes (6x10(6)) were seeded into rhCII gels (rhCII-cell) and injected subcutaneously into the backs of nude mice. For comparison, chondrocytes (6x10(6)) in culture medium (Med-cell) and cell-free rhCII gels (rhCII-gel) were similarly injected (n=24 animals, total of three injections/animal). After 6 weeks, the tissue constructs were harvested and analyzed.RESULTS: Chondrocytes with or without rhCII-gel produced white resilient tissue, which in histological sections had chondrocytes in lacunae-like structures. Extracellular matrix stained heavily with toluidine blue stain and had strongly positive collagen type II immunostaining. The tissue did not show any evidence of vascular invasion or mineralization. The cell-free rhCII-gel constructs showed no signs of cartilage tissue formation. Cartilage tissue produced by Med-cell was thin and macroscopically uneven, while the rhCII-cell construct was smooth and rounded piece of neotissue. RhCII-cell constructs were statistically thicker than Med-cell ones. However, no statistical differences were found between the groups in terms of glycosaminoglycan (GAG) content or biomechanical properties.CONCLUSIONS: These results show that rhCII-gel provides good expansion and mechanical support for the formation of cartilage neotissue. RhCII material may allow favorable conditions in the repair of chondral lesions.
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| 3. |
- Virén, Tuomas, et al.
(författare)
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Quantitative evaluation of spontaneously and surgically repaired rabbit articular cartilage using intra-articular ultrasound method in situ.
- 2010
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Ingår i: Ultrasound in Medicine and Biology. - : Elsevier. - 1879-291X .- 0301-5629. ; 36:5, s. 833-839
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Tidskriftsartikel (refereegranskat)abstract
- During the last decade, a major effort has been devoted to developing surgical methods for repairing localized articular cartilage lesions. Despite some promising results no ultimate breakthrough in surgical cartilage repair has been achieved. Improvements in repair techniques would benefit from more sensitive and quantitative methods for long-term follow-up of cartilage healing. In this study, the potential of a new ultrasound technique for detecting the compositional and structural changes in articular cartilage after surgery, using recombinant human type II collagen gel and spontaneous repair was, investigated. Rabbit knee joints containing intact (n = 13) and surgically (n = 8) or spontaneously (n = 5) repaired tissue were imaged in situ at 6 months after the operation using a clinical intravascular high-frequency (40 MHz) ultrasound device. Based on the ultrasound raw data, ultrasound reflection coefficient (R), integrated ultrasound reflection coefficient (IRC), apparent integrated backscattering coefficient (AIB) and ultrasound roughness index (URI) were determined for each sample. URI was significantly higher in both repair groups than in intact cartilage (p < 0.05). The reflection parameters (R and IRC) were significantly lower in surgically repaired cartilage (p < 0.05) than in intact cartilage. Furthermore, AIB was significantly higher in surgically repaired cartilage than in intact tissue (p < 0.05). To conclude, the integrity of the rabbit articular cartilage repair could be quantitatively evaluated with the nondestructive ultrasound approach. In addition, clinically valuable qualitative information on the changes in cartilage integration, structure and composition could be extracted from the ultrasound images. In the present study, the structure and properties of repaired tissue were inferior to native tissue at 6 months after the operation. The applied ultrasound device and probes are FDA approved and, thus, applicable for the quantitative in vivo evaluation of human articular cartilage.
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