| 1. |
- Cedervall, Jessica, et al.
(författare)
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Injection of embryonic stem cells into scarred rabbit vocal folds enhances healing and improves viscoelasticity : short-term results
- 2007
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Ingår i: The Laryngoscope. - Philadelphia : Lippincott Williams & Wilkins. - 0023-852X .- 1531-4995. ; 117:11, s. 2075-2081
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Scarring caused by trauma; postcancer treatment, or inflammation in the vocal folds is associated with stiffness of the lamina propria and results in severe voice problems. Currently there is no effective treatment. Human embryonic stem cells (hESC) have been recognized as providing a potential resource for cell transplantations, but in the undifferentiated state, they are generally not considered for therapeutic use due to risk of inadvertent development. This study assesses the functional potential of hESC to prevent or diminish scarring and improve viscoelasticity following grafting into scarred rabbit vocal folds.Study Design: hESC were injected into 22 scarred vocal folds of New Zealand rabbits. After 1 month, the vocal folds were dissected and analyzed for persistence of hESC by fluorescence in situ hybridization using a human specific probe, and for differentiation by evaluation in hematoxylin-eosin-stained tissues. Parallel-plate rheometry was used to evaluate the functional effects, i.e., viscoelastic properties, after treatment with hESC.Results: The results revealed significantly improved viscoelasticity in the hESC-treated vs. non-treated vocal folds. An average of 5.1% engraftment of human cells was found 1 month after hESC injection. In the hESC-injected folds, development compatible with cartilage, muscle and epithelia in close proximity or inter-mixed with the appropriate native V rabbit tissue was detected in combination with less scarring and improved viscoelasticity.Conclusions: The histology and location of the surviving hESC-derived cells strongly indicate that the functional improvement was caused by the injected cells, which were regenerating scarred tissue. The findings point toward a strong impact from the host microenvironment, resulting in a regional specific in vivo hESC differentiation. and regeneration of three; types of tissue in scarred vocal folds of adult rabbits.
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| 2. |
- Hertegard, S., et al.
(författare)
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Viscoelastic and histologic properties in scarred rabbit vocal folds after mesenchymal stem cell injection
- 2006
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Ingår i: The Laryngoscope. - : Wiley-Blackwell. - 0023-852X .- 1531-4995. ; 116:7, s. 1248-1254
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE/HYPOTHESIS:The aim of this study was to analyze the short-term viscoelastic and histologic properties of scarred rabbit vocal folds after injection of human mesenchymal stem cells (MSC) as well as the degree of MSC survival. Because MSCs are antiinflammatory and regenerate mesenchymal tissues, can MSC injection reduce vocal fold scarring after injury?STUDY DESIGN:Twelve vocal folds from 10 New Zealand rabbits were scarred by a localized resection and injected with human MSC or saline. Eight vocal folds were left as controls.MATERIAL AND METHODS:After 4 weeks, 10 larynges were stained for histology and evaluation of the lamina propria thickness. Collagen type I content was analyzed from six rabbits. MSC survival was analyzed by fluorescent in situ hybridization staining from three rabbits. Viscoelasticity for 10 vocal folds was analyzed in a parallel-plate rheometer.RESULTS:The rheometry on fresh-frozen samples showed decreased dynamic viscosity and lower elastic modulus (P<.01) in the scarred samples injected with MSC as compared with the untreated scarred group. Normal controls had lower dynamic viscosity and elastic modulus as compared with the scarred untreated and treated vocal folds (P<.01). Histologic analysis showed a higher content of collagen type 1 in the scarred samples as compared with the normal vocal folds and with the scarred folds treated with MSC. MSCs remained in all samples analyzed.CONCLUSIONS:The treated scarred vocal folds showed persistent MSC. Injection of scarred rabbit vocal folds with MSC rendered improved viscoelastic parameters and less signs of scarring expressed as collagen content in comparison to the untreated scarred vocal folds.
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| 3. |
- Vidovska, Daniela
(författare)
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Bimodal Hard/Soft Latex Blends
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Polymer dispersions are employed in a wide variety of applications as film formers. Especially in the coating-, paint-, pharmaceutical and hygiene industry polymer dispersions are to a large extent used as barriers, controlled-release agents and adhesives. Control and steering of the polymerization process has resulted in the production of core-shell structures with soft and hard (low glass transition temperature (Tg) and high Tg) constituents and molecular modifications to increase the adhesion to substrates by incorporating for instance acrylic acid groups. However, there is also a need for new materials that combine the properties of two or more polymeric or/and inorganic materials, which is not easily achieved by polymerizing to a single dispersion. The most natural way to achieve this is the blending of two dispersions. This provides the possibility to fine-tune the final properties of the film material. The focus of this thesis was to study the effect of composition, particle size and particle size ratio (soft particle diameter/hard particle diameter) on the mechanical viscoelastic film properties and morphology of hard/soft latex blends. Viscoelastic properties were determined both in the solid and in the melt state. The results were compared with theoretical predictions based on self-consistent mechanical modeling. Furthermore, the effect of the addition of a varying amount of silica nanoparticles on the viscoelasic properties, morphology and water permeability of the well-characterized hard/soft latex system was studied. A new empirical equation was established for the characterization of the modulus as a function of volume fraction and particle size ratio. The particle size ratio was shown to have an effect on the film forming properties as well as on the dynamic mechanical properties of the latex films. With increasing volume fraction of hard particles a modulus enhancement was obtained in the temperature range in between the individual Tg's of the neat polymeric materials. By introducing silica nanoparticles in the hard/soft latex blends the aggregation of these silica particles enhanced the dynamic modulus further. Pukanszky's model, originally derived for filled polymers and polymer blends, was shown to be a very useful tool for the evaluation of the yield stress of hard/soft latex blends.
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| 4. |
- Vidovska, Daniela, et al.
(författare)
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Tensile properties and interfacial interactions of bimodal hard/soft latex blends
- 2006
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Ingår i: Composite Interfaces. - 1568-5543. ; 13:8-9, s. 819-830
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the effect of composition, particle size and particle size ratio on the tensile properties of well-characterized hard/soft latex blends was investigated. Four blends of hard/soft latices, with varying particle sizes (either small or large), and volume fractions of 100/0, 80/20, 60/40, 50/50, 40/60, 20/80 and 0/100 were studied. The stress at break increased and the strain at break decreased as the amount of hard particles in the blend increased. A simple model, introduced by Pukanszky for filled polymers and polymer blends, proved to be a very useful tool for evaluating the tensile properties of the latex blends. Parameter B of the model could be related to the specific surface of the dispersed hard particles and the particle size ratio. Increasing the specific surface of the dispersed hard particles resulted in an increase in parameter B. The influence of particle size ratio on parameter B was shown to depend on the formation of aggregates.
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