Minimal information for studies of extracellular vesicles (MISEV2023): From basic to advanced approaches

Extracellular vesicles (EVs), through their complex cargo, can reflect the state of their cell of origin and change the functions and phenotypes of other cells. These features indicate strong biomarker and therapeutic potential and have generated broad interest, as evidenced by the steady year-on-year increase in the numbers of scientific publications about EVs. Important advances have been made in EV metrology and in understanding and applying EV biology. However, hurdles remain to realising the potential of EVs in domains ranging from basic biology to clinical applications due to challenges in EV nomenclature, separation from non-vesicular extracellular particles, characterisation and functional studies. To address the challenges and opportunities in this rapidly evolving field, the International Society for Extracellular Vesicles (ISEV) updates its 'Minimal Information for Studies of Extracellular Vesicles', which was first published in 2014 and then in 2018 as MISEV2014 and MISEV2018, respectively. The goal of the current document, MISEV2023, is to provide researchers with an updated snapshot of available approaches and their advantages and limitations for production, separation and characterisation of EVs from multiple sources, including cell culture, body fluids and solid tissues. In addition to presenting the latest state of the art in basic principles of EV research, this document also covers advanced techniques and approaches that are currently expanding the boundaries of the field. MISEV2023 also includes new sections on EV release and uptake and a brief discussion of in vivo approaches to study EVs. Compiling feedback from ISEV expert task forces and more than 1000 researchers, this document conveys the current state of EV research to facilitate robust scientific discoveries and move the field forward even more rapidly

Search for subsolar-mass binaries in the first half of Advanced LIGO's and Advanced Virgo's third observing run

We report on a search for compact binary coalescences where at least one binary component has a mass between 0.2 M⊙ and 1.0 M⊙ in Advanced LIGO and Advanced Virgo data collected between 1 April 2019 1500 UTC and 1 October 2019 1500 UTC. We extend our previous analyses in two main ways: we include data from the Virgo detector and we allow for more unequal mass systems, with mass ratio q ≥ 0.1. We do not report any gravitational-wave candidates. The most significant trigger has a false alarm rate of 0.14 yr-1. This implies an upper limit on the merger rate of subsolar binaries in the range [220-24200] Gpc-3 yr-1, depending on the chirp mass of the binary. We use this upper limit to derive astrophysical constraints on two phenomenological models that could produce subsolar-mass compact objects. One is an isotropic distribution of equal-mass primordial black holes. Using this model, we find that the fraction of dark matter in primordial black holes in the mass range 0.2 M &lt; mPBH &lt; 1.0 M⊙ is fPBH ≡ ΩPBH/ΩDM ≤ 6%. This improves existing constraints on primordial black hole abundance by a factor of ∼3. The other is a dissipative dark matter model, in which fermionic dark matter can collapse and form black holes. The upper limit on the fraction of dark matter black holes depends on the minimum mass of the black holes that can be formed: the most constraining result is obtained at Mmin = 1 M⊙, where fDBH ≡ ΩDBH/ΩDM ≤ 0.003%. These are the first constraints placed on dissipative dark models by subsolar-mass analyses.<br/

Ultralight vector dark matter search using data from the KAGRA O3GK run

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM

GWTC-3: Compact Binary Coalescences Observed by LIGO and Virgo during the Second Part of the Third Observing Run

peer reviewedThe third Gravitational-Wave Transient Catalog (GWTC-3) describes signals detected with Advanced LIGO and Advanced Virgo up to the end of their third observing run. Updating the previous GWTC-2.1, we present candidate gravitational waves from compact binary coalescences during the second half of the third observing run (O3b) between 1 November 2019, 15∶00 Coordinated Universal Time (UTC) and 27 March 2020, 17∶00 UTC. There are 35 compact binary coalescence candidates identified by at least one of our search algorithms with a probability of astrophysical origin pastro>0.5. Of these, 18 were previously reported as low-latency public alerts, and 17 are reported here for the first time. Based upon estimates for the component masses, our O3b candidates with pastro>0.5 are consistent with gravitational-wave signals from binary black holes or neutron-star-black-hole binaries, and we identify none from binary neutron stars. However, from the gravitational-wave data alone, we are not able to measure matter effects that distinguish whether the binary components are neutron stars or black holes. The range of inferred component masses is similar to that found with previous catalogs, but the O3b candidates include the first confident observations of neutron-star-black-hole binaries. Including the 35 candidates from O3b in addition to those from GWTC-2.1, GWTC-3 contains 90 candidates found by our analysis with pastro>0.5 across the first three observing runs. These observations of compact binary coalescences present an unprecedented view of the properties of black holes and neutron stars

Search for gravitational-lensing signatures in the full third observing run of the LIGO-Virgo network

Gravitational lensing by massive objects along the line of sight to the source causes distortions of gravitational wave-signals; such distortions may reveal information about fundamental physics, cosmology and astrophysics. In this work, we have extended the search for lensing signatures to all binary black hole events from the third observing run of the LIGO--Virgo network. We search for repeated signals from strong lensing by 1) performing targeted searches for subthreshold signals, 2) calculating the degree of overlap amongst the intrinsic parameters and sky location of pairs of signals, 3) comparing the similarities of the spectrograms amongst pairs of signals, and 4) performing dual-signal Bayesian analysis that takes into account selection effects and astrophysical knowledge. We also search for distortions to the gravitational waveform caused by 1) frequency-independent phase shifts in strongly lensed images, and 2) frequency-dependent modulation of the amplitude and phase due to point masses. None of these searches yields significant evidence for lensing. Finally, we use the non-detection of gravitational-wave lensing to constrain the lensing rate based on the latest merger-rate estimates and the fraction of dark matter composed of compact objects

Search for eccentric black hole coalescences during the third observing run of LIGO and Virgo

Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass M&gt;70 M⊙) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities 0&lt;e≤0.3 at 0.33 Gpc−3 yr−1 at 90\% confidence level

Combined Action of Endothelial and Mesenchymal Niche Cells to Amplify Hematopoietic Progenitor Expansion in a Humanized System

Abstract The hematopoietic stem cell (HSC) niche is an anatomically confined space governing HSC proliferation, differentiation and self renewal. Recent research identified distinct compartments described as stromal and vascular niches. This study was initiated to directly compare mesenchymal stromal cell (MSC) and vascular endothelial progenitor cell (EPC) contribution to niche functions in a humanized co-culture system. MSCs and EPCs were propagated under animal protein-free conditions following recently established protocols. Autologous MSC-EPC pairs were established to avoid donor variation. Purified CD34+ hematopoietic progenitor cells (HPCs) and HSCs were used as responders in a cytokine-driven (IL-3, 6ng/mL; Flt-3-L, 50ng/mL; SCF, 20ng/mL) niche cell-regulated HPC co-culture system. Four different standard media were employed to compare fully serum-free conditions with humanized cultures that were supplemented with pooled human platelet lysate (pHPL) as a source of platelet-derived growth factors present within the niche. Primary expansion culture with and without niche cell support was followed by colony forming cell (CFC) assays to determine maintenance of clonogenicity. Humanized liquid cultures supplemented with 10% pHPL without niche cell support were more efficient than parallel serum-free cultures under three of four medium conditions resulting in a mean 16–84-fold increase in nucleated cell progeny within 11 days. Both MSCs and EPCs further amplified HPC proliferation, MSC actually up to 341-fold, confirming recently published results. Interestingly, the supportive effect of MSCs or EPCs was constantly more pronounced in humanized pHPL-supplemented compared to completely serum-free cultures, indicating a peculiar role of the natural platelet-derived growth factors in this process. Surprisingly, the combination of equal cumulative numbers of MSCs + EPCs constantly resulted in the highest HPC proliferation. This produced an up to 567-fold increase indicating at least nine population doublings within only 11 days. Under all tested conditions the HPC progeny mainly comprised differentiating myeloid cells. Consecutive CFC assays revealed that liquid culture supplemented with 10%HPL were more efficient than serum-free cultures resulting in a measurable 1.2–4.5 fold CFC expansion under three of four tested medium conditions. Both MSC and EPC initiated a more than 6-fold increase of CFCs. CFC expansion through combined action of MSCs + EPCs resulted in a maximum of 23.5-fold CFC increase in pHPL-supplemented cultures. We demonstrate for the first time that HPC expansion can be modulated in a fully humanized co-culture system based on the use of pHPL as a natural source of human platelet-derived growth factors. Our data indicate that the combination of MSCs + EPCs is at least as efficient in supporting HPC proliferation and CFC amplification as either niche cell compartment alone. We speculate that human platelet-derived factors may avoid premature HSC exhaustion in this system. The humanized co-culture thus provides a novel model system for subtractive analyses of HPC and HSC-niche cell interactions. It also builds the basis for further developments towards more effective animal serum-free HSC expansion strategies.</jats:p

Structural Model of the Gas Vesicle Protein GvpA and Analysis of GvpA Mutants in vivo.

Gas vesicles are gas-filled protein structures increasing the buoyancy of cells. The gas vesicle envelope is mainly constituted by the 8-kDa protein GvpA forming a wall with a water excluding inner surface. A structure of GvpA is not available; recent solid-state NMR results suggest a coil-α-β-β-α-coil fold. We obtained a first structural model of GvpA by high-performance de novo modeling. ATR-FTIR spectroscopy supported this structure. A dimer of GvpA was derived that could explain the formation of the protein monolayer in the gas vesicle wall. The hydrophobic inner surface is mainly constituted by anti-parallel β-strands. The proposed structure allows the pinpointing of contact sites that were mutated and tested for the ability to form gas vesicles in haloarchaea. Mutations in α-helix I and α-helix II, but also in the β-turn affected the gas vesicle formation, whereas other alterations had no effect. All mutants supported the structural features deduced from the model. The proposed GvpA dimers allow the formation of a monolayer protein wall, also consistent with protease treatments of isolated gas vesicles