Biology subjects

Andresen, V.

Publications and source records attributed to Andresen, V..

3 recordsLinked to original sources

bioRxiv2023

In vivo optimized three-photon imaging of intact mouse tibia links plasma cell motility to functional states in the bone marrow.

Intravital multi-photon imaging of the bone marrow is crucial to the study of cellular dynamics, communication with the microenvironment and functions, however, imaging of deep tissue areas is challenging and minimally invasive methods for deep-marrow imaging in intact long bones are needed. We developed a high pulse energy 1650 nm laser prototype, which permits to surpass >100 {micro}m thick cortical bone and to perform three-photon microscopy (3PM) in more than 400 {micro}m depth in the marrow cavity of intact mouse tibia in vivo. Its unique 3 and 4 MHz laser repetition rates allowed us to analyze motility patterns of rare cells over large fields of view deep within the unperturbed marrow. In this way, we found a bi-modal migratory behavior of marrow plasma cells. Besides, the analysis of third harmonics generation (THG) in the tibia identified this signal to be a label-free indicator of the abundance of cellular organelles, in particular the endoplasmic reticulum, reflecting protein biosynthesis capacity. We found that only one third of the plasma cells in the tibia marrow of adult mice have a strong THG signal and, thus, a high protein synthesis capacity, while the other two thirds of plasma cells display a low THG signal. Finally, we identified an inverse link between migratory behavior and THG signal strength in marrow plasma cells. As in these cells, the protein biosynthesis capacity indicated by a strong THG signal is mainly associated with antibody secretion, we could relate motility to functional states of plasma cells in vivo. Our 3PM method retains the ability to connect cellular dynamics to protein biosynthesis capacity in various marrow cell types beyond plasma cells, as THG is a ubiquitous signal, opening new perspectives on understanding how tissue microenvironment impacts on cellular functions in the bone marrow.

biophysics↗

bioRxiv2020

Intravital Deep-Tumor Single-Beam 2-, 3- and 4-Photon Microscopy

Three-photon excitation has recently been introduced to perform intravital microscopy in deep, previously inaccessible layers of the brain. The applicability of deep-tissue three-photon excitation in more heterogeneously structured, dense tissue types remains, however, unclear. Here we show that in tumors and bone, high-pulse-energy low-duty-cycle infrared excitation near 1300 and 1700 nm enables two-up to fourfold increased tissue penetration compared to conventional 2-photon excitation. Using a single laser line, simultaneous 2-, 3- and 4-photon processes are effectively induced, enabling the simultaneous detection of blue to far-red fluorescence together with second and third harmonic generation. This enables subcellular resolution at power densities in the focus that are not phototoxic to live cells and without color aberration. Thus, infrared high-pulse-energy low-duty-cycle excitation advances deep intravital microscopy in strongly scattering tissue and, in a single scan, delivers rich multi-parameter datasets from cells and complex organ structures.

cancer biology↗

bioRxiv2018

Increased Adhesion Of CML Cells By ABL1 Tyrosine Kinase Inhibitors Induce Tunneling Nanotubes

Summary statementThis study describes the effects of tyrosine kinase inhibitors on tunneling nanotube formation via increased adhesion through {beta}-integrin in chronic myeloid leukemia cells.\n\nAbstractThe actin-containing cell-to-cell communicator tunneling nanotube (TNT) is involved in regulation of cell death threshold of leukemic cells, while the mechanism of TNT regulation is mostly unknown. We have investigated TNT formation and its response to treatment in chronic myeloid leukemia (CML) cells with the pathognomonic chimeric fusion kinase BCR-ABL1 after treatment with the tyrosine kinase inhibitor nilotinib and interferon-. Bone marrow cells of chronic phase CML patients and the CML cell line Kcl-22 formed few or no TNTs. Nilotinib and interferon- treatment induced TNT formation in Kcl-22 cells and were found to be linked to increased adherence to fibronectin coated surfaces by restoration of {beta}1-integrin function. This suggests modulation of TNT cell-cell communication in CML as a novel mechanism in kinase inhibitor therapy of CML.

cell biology↗