Cardiac Progenitor Cell–Derived Extracellular Vesicles Reduce Infarct Size and Associate with Increased Cardiovascular Cell Proliferation

Cell transplantation studies have shown that injection of progenitor cells can improve cardiac function after myocardial infarction (MI). Transplantation of human cardiac progenitor cells (hCPCs) results in an increased ejection fraction, but survival and integration are low. Therefore, paracrine factors including extracellular vesicles (EVs) are likely to contribute to the beneficial effects. We investigated the contribution of EVs by transplanting hCPCs with reduced EV secretion. Interestingly, these hCPCs were unable to reduce infarct size post-MI. Moreover, injection of hCPC-EVs did significantly reduce infarct size. Analysis of EV uptake showed cardiomyocytes and endothelial cells primarily positive and a higher Ki67 expression in these cell types. Yes-associated protein (YAP), a proliferation marker associated with Ki67, was also increased in the entire infarcted area. In summary, our data suggest that EV secretion is the driving force behind the short-term beneficial effect of hCPC transplantation on cardiac recovery after MI

Coupling of Rotational Motion with Shape Fluctuations of Core-shell Microgels Having Tunable Softness

The influence of shape fluctuations on deformable thermosensitive microgels in aqueous solution is investigated by dynamic light scattering (DLS) and depolarized dynamic light scattering (DDLS). The systems under study consist of a solid core of polystyrene and a thermosensitive shell of cross-linked poly(N-isopropylacrylamide) (PNIPA) without and with embedded palladium nanoparticles. PNIPA is soluble in water, but has a lower critical solution temperature at 32 C (LCST). Below the LCST the PNIPA shell is swollen. Here we find that besides translational and rotational diffusion, the particles exhibit additional dynamics resulting from shape fluctuations. This leads to a pronounced apparent increase of the rotational diffusion coefficient. Above the transition temperature the shell collapses and provides a rather tight envelope of the core. In this state the dynamics of the shell is frozen and the core-shell particles behave like hard spheres. A simple physical model is presented to capture and explain the essentials of the coupling of rotational motion and shape fluctuations.Comment: 9 pages, 7 figure

Modeling of Intermediate Structures and Chain Conformation in Silica-Latex Nanocomposites Observed by SANS During Annealing

The evolution of the polymer structure during nanocomposite formation and annealing of silica-latex nanocomposites is studied using contrast-variation small angle neutron scattering. The experimental system is made of silica nanoparticles (Rsi \approx 8 nm) and a mixture of purpose-synthesized hydrogenated and deuterated nanolatex (Rlatex \approx 12.5 nm). The progressive disappearance of the latex beads by chain interdiffusion and release in the nanocomposites is analyzed quantitatively with a model for the scattered intensity of hairy latex beads and an RPA description of the free chains. In silica-free matrices and nanocomposites of low silica content (7%v), the annealing procedure over weeks at up to Tg + 85 K results in a molecular dispersion of chains, the radius of gyration of which is reported. At higher silica content (20%v), chain interdiffusion seems to be slowed down on time-scales of weeks, reaching a molecular dispersion only at the strongest annealing. Chain radii of gyration are found to be unaffected by the presence of the silica filler

Use of anomalous small-angle X-ray scattering for the investigation of highly charged colloids

We present a study of the radial structure of a spherical polyelectrolyte brushes by anomalous small-angle X-ray scattering. The spherical polyelectrolyte brushes consist of a solid poly( styrene) core of ca : 100 nm diameter onto which long linear chains of poly( acrylic acid) (PAA) are densely grafted. A sufficiently high pH, these polyelectrolyte chains are fully charged. Rubidium ions are used as counterions because their adsorption edge (15 199.6 eV) can be conventiently reached by synchrotron radiation. By performing small-angle X-ray scattering studies at different energies of the incident radiation, the contribution of the Rb+ counterions can be analyzed separately. The scattering contribution of the counterions can be derived and compared to the scattering intensity of the entire particle. The distributions of the macro-ion and of the counterions are shown to be very similiar. This shows that the counterions must be confined within the brush