University of Twente

About: University of Twente is a education organization based out in Enschede, Overijssel, Netherlands. It is known for research contribution in the topics: Context (language use) & Population. The organization has 15890 authors who have published 39988 publications receiving 1173424 citations. The organization is also known as: Universiteit Twente.

First-principles study of magnetization relaxation enhancement and spin transfer in thin magnetic films

Abstract: The interface-induced magnetization damping of thin ferromagnetic films in contact with normal-metal layers is calculated from first principles for clean and disordered Fe/Au and Co/Cu interfaces. Interference effects arising from coherent scattering turn out to be very small, consistent with a very small magnetic coherence length. Because the mixing conductances which govern the spin transfer are to a good approximation real-valued, the spin pumping can be described by an increased Gilbert damping factor but an unmodified gyromagnetic ratio. The results also confirm that the spin-current-induced magnetization torque is an interface effect.

Trophic Effects of Mesenchymal Stem Cells in Chondrocyte Co-Cultures are Independent of Culture Conditions and Cell Sources

Abstract: Earlier, we have shown that the increased cartilage production in pellet co-cultures of chondrocytes and bone marrow-derived mesenchymal stem cells (BM-MSCs) is due to a trophic role of the MSC in stimulating chondrocyte proliferation and matrix production rather than MSCs actively undergoing chondrogenic differentiation. These studies were performed in a culture medium that was not compatible with the chondrogenic differentiation of MSCs. In this study, we tested whether the trophic role of the MSCs is dependent on culturing co-culture pellets in a medium that is compatible with the chondrogenic differentiation of MSCs. In addition, we investigated whether the trophic role of the MSCs is dependent on their origins or is a more general characteristic of MSCs. Human BM-MSCs and bovine primary chondrocytes were co-cultured in a medium that was compatible with the chondrogenic differentiation of MSCs. Enhanced matrix production was confirmed by glycosaminoglycans (GAG) quantification. A species-specific quantitative polymerase chain reaction demonstrated that the cartilage matrix was mainly of bovine origin, indicative of a lack of the chondrogenic differentiation of MSCs. In addition, pellet co-cultures were overgrown by bovine cells over time. To test the influence of origin on MSCs' trophic effects, the MSCs isolated from adipose tissue and the synovial membrane were co-cultured with human primary chondrocytes, and their activity was compared with BM-MSCs, which served as control. GAG quantification again confirmed increased cartilage matrix production, irrespective of the source of the MSCs. EdU staining combined with cell tracking revealed an increased proliferation of chondrocytes in each condition. Irrespective of the MSC source, a short tandem repeat analysis of genomic DNA showed a decrease in MSCs in the co-culture over time. Our results clearly demonstrate that in co-culture pellets, the MSCs stimulate cartilage formation due to a trophic effect on the chondrocytes rather than differentiating into chondrocytes, irrespective of culture condition or origin. This implies that the trophic effect of MSCs in co-cultures is a general phenomenon with potential implications for use in cartilage repair strategies.