| 51. |
- Kördel, Mikael, et al.
(author)
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Biological Laboratory X-Ray Microscopy
- 2019
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In: X-Ray Nanoimaging. - : SPIE - International Society for Optical Engineering. - 9781510629189
-
Conference paper (peer-reviewed)abstract
- Zone-plate-based soft x-ray microscopes operating in the water window allow high-resolution and high-contrast imaging of intact cells in their near-native state. Laboratory-source-based x-ray microscopes are an important complement to the accelerator-based instruments, providing high accessibility and allowing close integration with other cell-biological techniques. Here we present recent biological applications using the Stockholm laboratory water-window x-ray microscope, which is based on a liquid-nitrogen-jet laser-plasma source. Technical improvements to the microscope in the last few years have resulted in increased x-ray flux at the sample and significantly improved stability and reliability. In addition to this, vibrations in key components have been measured, analyzed and reduced to improve the resolution to 25 nm half-period. The biological applications include monitoring the development of carbon-dense vesicles in starving human embryonic kidney cells (HEK293T), imaging the interaction between natural killer (NK) cells and HEK293T target cells, and most recently studying a newly discovered giant DNA virus and the process of viral replication inside a host amoeba. All biological imaging was done on cryo-frozen hydrated samples in 2D and in some cases 3D.
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| 52. |
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| 53. |
- Manneberg, Otto, et al.
(author)
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A three-dimensional ultrasonic cage for characterization of individual cells
- 2008
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 93, s. 063901-
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Journal article (peer-reviewed)abstract
- We demonstrate enrichment, controlled aggregation, and manipulation of microparticles and cells by an ultrasonic cage integrated in a microfluidic chip compatible with high-resolution optical microscopy. The cage is designed as a dual-frequency resonant filleted square box integrated in the fluid channel. Individual particles may be trapped three dimensionally, and the dimensionality of one-dimensional to three-dimensional aggregates can be controlled. We investigate the dependence of the shape and position of a microparticle aggregate on the actuation voltages and aggregate size, and demonstrate optical monitoring of individually trapped live cells with submicrometer resolution.
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| 54. |
- Manneberg, Otto, et al.
(author)
-
Flow-free transport of cells in microchannels by frequency-modulated ultrasound
- 2009
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In: Lab on a Chip. - 1473-0197 .- 1473-0189. ; 9, s. 833-837
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Journal article (peer-reviewed)abstract
- We demonstrate flow-free transport of cells and particles by the use of frequency-modulated ultrasonic actuation of a microfluidic chip. Two different modulation schemes are combined: A rapid (1 kHz) linear frequency sweep around similar to 6.9 MHz is used for two-dimensional spatial stabilization of the force field over a 5 mm long inlet channel of constant cross section, and a slow (0.2-0.7 Hz) linear frequency sweep around similar to 2.6 MHz is used for flow-free ultrasonic transport and positioning of cells or particles. The method is used for controlling the motion and position of cells monitored with high-resolution optical microscopy, but can also be used more generally for improving the robustness and performance of ultrasonic manipulation micro-devices.
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| 55. |
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| 56. |
- McCann, Fiona E., et al.
(author)
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The activating NKG2D ligand MHC class I-related chain a transfers from target cells to NK cells in a manner that allows functional consequences
- 2007
-
In: Journal of Immunology. - : The American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 178:6, s. 3418-3426
-
Journal article (peer-reviewed)abstract
- Recently, it has become apparent that surface proteins commonly transfer between immune cells in contact. Inhibitory receptors and ligands exchange between cells during NK cell surveillance and we report here that NK cells also acquire activating ligands from target cells. Specifically, the stress-inducible activating ligand for NKG2D, MHC class I-related chain A (MICA), transferred to NK cells upon conjugation with MICA-expressing target cells. Acquisition of MICA from target cells was dependent on cell contact and occurred after accumulation of MICA at the immunological synapse. Moreover, transfer of MICA was facilitated by specific molecular recognition via NKG2D and augmented by Src kinase signaling. Importantly, MICA associated with its new host NK cell membrane in an orientation that allowed engagement with NKG2D in trans and indeed could down-regulate NKG2D in subsequent homotypic interactions with other NK cells. MICA captured from target cells could subsequently transfer between NK cells and, more importantly, NK cell degranulation was triggered in such NK cell-NK cell interactions. Thus, NK cells can influence other NK cells with proteins acquired from target cells and our data specifically suggest that NK cells could lyse other NK cells upon recognition of activating ligands acquired from target cells. This mechanism could constitute an important function for immunoregulation of NK cell activity.
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| 57. |
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| 58. |
- Nilsson, Jesper, 1984, et al.
(author)
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Light-induced cytotoxicity of a photochromic spiropyran
- 2011
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In: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1364-548X .- 1359-7345. ; 47:39, s. 11020-11022
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Journal article (peer-reviewed)abstract
- In this work we present a novel water soluble spiropyran photoswitch that can be photonically activated inside live cells from a form that has no significant effect on the cellular survival to a form that induces a dramatic toxic response.
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| 59. |
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| 60. |
- Oei, Vincent Yi Sheng, et al.
(author)
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Intrinsic Functional Potential of NK-Cell Subsets Constrains Retargeting Driven by Chimeric Antigen Receptors
- 2018
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In: CANCER IMMUNOLOGY RESEARCH. - : AMER ASSOC CANCER RESEARCH. - 2326-6066 .- 2326-6074. ; 6:4, s. 467-480
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Journal article (peer-reviewed)abstract
- Natural killer (NK) cells hold potential as a source of allogeneic cytotoxic effector cells for chimeric antigen receptor (CAR)-mediated therapies. Here, we explored the feasibility of transfecting CAR-encoding mRNA into primary NK cells and investigated how the intrinsic potential of discrete NK-cell subsets affects retargeting efficiency. After screening five second- and third-generation anti-CD19 CAR constructs with different signaling domains and spacer regions, a third-generation CAR with the CH2-domain removed was selected based on its expression and functional profiles. Kinetics experiments revealed that CAR expression was optimal after 3 days of IL15 stimulation prior to transfection, consistently achieving over 80% expression. CAR-engineered NK cells acquired increased degranulation toward CD19(+) targets, and maintained their intrinsic degranulation response toward CD19(-) K562 cells. The response of redirected NK-cell subsets against CD19(+) targets was dependent on their intrinsic thresholds for activation determined through both differentiation and education by killer cell immunoglobulin-like receptors (KIR) and/or CD94/NKG2A binding to self HLA class I and HLA-E, respectively. Redirected primary NK cells were insensitive to inhibition through NKG2A/HLA-E interactions but remained sensitive to inhibition through KIR depending on the amount of HLA class I expressed on target cells. Adaptive NK cells, expressing NKG2C, CD57, and self-HLA-specific KIR(s), displayed superior ability to kill CD19(+), HLA low, or mismatched tumor cells. These findings support the feasibility of primary allogeneic NK cells for CAR engineering and highlight a need to consider NK-cell diversity when optimizing efficacy of cancer immunotherapies based on CAR-expressing NK cells.
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