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Multiple myeloma is an incurable cancer of antibody-producing plasma cells. Hepatocyte growth factor (HGF), a cytokine aberrantly expressed in half of myeloma patients, is involved in myeloma pathogenesis by enhancing myeloma growth and invasiveness, and may play a role in myeloma bone disease by inhibiting osteoblastogenesis. In this study, we investigated whether extracellular vesicles (EVs) may play a role in HGF signaling between myeloma cells and osteoblast-like target cells. EVs from the HGF-positive cell line JJN-3 and the HGF-negative cell line INA-6, and from bone marrow plasma and primary human myeloma cells, were isolated using sequential centrifugation techniques and the presence of HGF on the EV-surface was investigated with ELISA. EVs from both cell lines were added to an established bioassay where HGF is known to induce interleukin-11 secretion in osteoblast-like cells. Our results show that HGF was bound to the surface of JJN-3-derived EVs, while INA-6-derived EVs were negative for HGF. Only JJN-3-derived EVs induced IL-11 secretion in osteoblast-like recipient cells. When osteoblast-like cells were preincubated with a specific HGF-receptor (c-Met) inhibitor, no induction of interleukin-11 was observed. Downstream c-Met phosphorylation was demonstrated by immunoblotting. EVs isolated from bone marrow plasma and primary myeloma cells were HGF-positive for a subset of myeloma patients. Taken together, this work shows for the first time that HGF bound on the surface of myeloma-derived EVs can effectuate HGF/c-Met signaling in osteoblast-like cells. Myeloma-derived EVs may play a role in myeloma bone disease by induction of the osteoclast-activating cytokine interleukin-11 in osteoblasts.

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Amyloid plaques composed of fibrillar Amyloid-ß (Aß) are hallmarks of Alzheimer's disease. However, Aß fibrils are morphologically heterogeneous. Conformation sensitive luminescent conjugated oligothiophenes (LCOs) are versatile tools for monitoring such fibril polymorphism in vivo and in vitro. Biophysical methods applied on in vitro generated Aß fibrils, stained with LCOs with different binding and fluorescence properties, can be used to characterize the Aß fibrillation in depth, far beyond that possible for in vivo generated amyloid plaques. In this study, in vitro fibrillation of the Aß1-40 peptide was monitored by time-lapse transmission electron microscopy, LCO fluorescence, and atomic force microscopy. Differences in the LCO binding in combination with nanoscale imaging revealed that spectral variation correlated with fibrils transforming from solitary filaments (Ø~2.5 nm) into higher order bundled structures (Ø~5 nm). These detailed in vitro experiments can be used to derive data that reflects the heterogeneity of in vivo generated Aß plaques observed by LCO fluorescence. Our work provides new structural basis for targeted drug design and molecular probe development for amyloid imaging.

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Deposition of aggregated Aß peptide in the brain is one of the major hallmarks of Alzheimer's disease. Using a combination of two structurally different, but related, hypersensitive fluorescent amyloid markers, LCOs, reporting on separate ultrastructural elements, we show that conformational rearrangement occurs within Aß plaques of transgenic mouse models as the animals age. This important mechanistic insight should aid the design and evaluation of experiments currently using plaque load as readout.

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In this study, the relation of the nanostructure of cell walls with their texture was investigated for six different apple cultivars. Cell wall material (CWM) and cellulose microfibrils were imaged by atomic force microscope (AFM). The mean diameter of cellulose microfibrils for each cultivar was estimated based on the AFM height topographs obtained using the tapping mode of dried specimens. Additionally, crystallinity of cellulose microfibrils and pectin content was determined. Texture of apple cultivars was evaluated by sensory and instrumental analysis. Differences in cellulose diameter as determined from the AFM height topographs of the nanostructure of cell walls of the apple cultivars are found to relate to the degree of crystallinity and pectin content. Cultivars with thicker cellulose microfibrils also revealed crisper, harder and juicier texture, and greater acoustic emission. The data suggest that microfibril thickness affects the mechanical strength of cell walls which has consequences for sensory and instrumental texture.

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