Improved Reversion of Calcifications in Porcine Aortic Heart Valves Using Elastin-Targeted Nanoparticles

Calcified aortic valve disease in its final stage leads to aortic valve stenosis, limiting cardiac function. To date, surgical intervention is the only option for treating calcific aortic valve stenosis. This study combined controlled drug delivery by nanoparticles (NPs) and active targeting by antibody conjugation. The chelating agent diethylenetriaminepentaacetic acid (DTPA) was covalently bound to human serum albumin (HSA)-based NP, and the NP surface was modified using conjugating antibodies (anti-elastin or isotype IgG control). Calcification was induced ex vivo in porcine aortic valves by preincubation in an osteogenic medium containing 2.5 mM sodium phosphate for five days. Valve calcifications mainly consisted of basic calcium phosphate crystals. Calcifications were effectively resolved by adding 1-5 mg DTPA/mL medium. Incubation with pure DTPA, however, was associated with a loss of cellular viability. Reversal of calcifications was also achieved with DTPA-coupled anti-elastin-targeted NPs containing 1 mg DTPA equivalent. The addition of these NPs to the conditioned media resulted in significant regression of the valve calcifications compared to that in the IgG-NP control without affecting cellular viability. These results represent a step further toward the development of targeted nanoparticular formulations to dissolve aortic valve calcifications.

An integrated ion trap for the photon-ion spectrometer at PETRA III

We have added a multipole ion trap to the existing photon-ion spectrometer at PETRA III (PIPE). Its hybrid structure combines a ring-electrode trap with a segmented 16-pole trap. The interaction of gases and ions with extreme ultraviolet radiation from the beamline P04 is planned to be investigated with the newly installed multipole trap. The research focus lies on radiation-induced chemical reactions that take place in the interstellar medium or in the atmospheres of planets, including natural as well as man-made processes that are important in the Earth's atmosphere. In order to determine the mass-to-charge ratio of the stored ions as efficiently as possible, we are using an ion time-of-flight spectrometer. With this technique, all stored ions can be detected simultaneously. To demonstrate the possibilities of the trap setup, two experiments have been carried out: The photoionization of xenon and the ion-impact ionization of norbornadiene. This type of ion-impact ionization can, in principle, also take place in planetary atmospheres. In addition to ionization by photon or ion impact, chemical reactions of the trapped ions with neutral atoms or molecules in the gas phase have been observed. The operation of the trap enables us to simulate conditions similar to those in the ionosphere.