Development of a Novel Adapter to Enable Less-Invasive Left Ventricular Assist Device Implantation via the Left Ventricular Apex.

The first prototype of an adapter to enable left ventricular assist device (LVAD) implantation solely via the left ventricular (LV) apex and without requiring cardiopulmonary bypass (CPB) was tested in healthy and acutely failing pig hearts. The adapter consists of a fixation, blood guiding, and connecting module fitting to a HeartMate 3 (HM3; Abbott, Chicago, IL) pump. Implantation was performed via a left thoracotomy in five pigs (96 ± 18 kg). Invasive blood pressure was measured before (CTRL), 30 minutes after HM3 initiation (HM3_CTRL), during acute heart failure (HF) induced by rapid pacing (CTRL_HF), and 5 minutes after initiating HM3 support (HM3_HF). To further estimate the LVAD performance, blood pressure amplitudes were calculated in the healthy heart without (CTRL) and with HM3 support (HM3_CTRL) as: systolic-diastolic blood pressure. Our adapter implantation and connection to the HM3 pump succeeded in all animals. Compared to the normal beating healthy heart, blood pressure amplitudes were significantly smaller during HM3 support (CTRL: 41 ± 5 mm Hg vs. HM3_CTRL: 20 ± 4 mm Hg; p < 0.05). Under HF conditions, mean blood pressure returned to normal values after pump initiation (CTRL_HF: 29 ± 6 mm Hg, HM3_HF: 83 ± 24 mm Hg). The adapter prototype allowed safe, straightforward, and less-invasive LVAD implantation solely via the LV apex without using CPB and support of the LV during acute HF in the pig heart.

Recording electric potentials from single adherent cells with 3D microelectrode arrays after local electroporation.

This short communication reports on the innovative method of the local micro-invasive needle electroporation (LOMINE) of single adherent cells. The investigation of cellular reactions in living cell cultures represents a fundamental method, e.g. for drug development and environmental monitoring. Existing classical methods for intracellular measurements using, e.g. patch clamp techniques are time-consuming and complex. Present patch-on-chip systems are limited to the investigation of single cells in suspension. Nevertheless, the most part of the cells of the human body is adherently growing. Therefore, we develop a new chip system for the growth of adherent cells with 64 micro-structured needle electrodes as well as 128 dielectrophoretic electrodes, located within a measuring area of 1 mm(2). With this analytical chip, the intracellular investigation of electro-chemical changes and processes in adherently growing cells will become possible in the near future. Here, we present first intracellular measurements with this chip system.

Modular glass chip system measuring the electric activity and adhesion of neuronal cells--application and drug testing with sodium valproic acid.

We developed a modular neurochip system by combining a small (16x16 mm2) glass neurochip (GNC) with a homemade head stage and commercial data acquisition hardware and software. The system is designed for the detection of the electric activity of cultivated nerve or muscle cells by a 52-microelectrode array (MEA). In parallel, cell adhesion can be registered from the electric impedance of an interdigitated electrode structure (IDES). The GNC was tested with various cell lines and primary cells. It is fully autoclavable and re-useable. Murine embryonic primary cells were used as a model system to correlate the electric activity and adhesion of neuronal networks in a drug test with sodium valproic acid. The test showed the advantage of the parallel IDES and MEA measurements, i.e. the parallel detection of cytotoxic and neurotoxic effects. Toxic exposure of the cells during neuronal network formation allows for the characterization of developmental neurotoxic effects even at drug concentrations below the EC50-value for acute neurotoxic effects. At high drug concentrations, the degree of cytotoxic damage can still be assessed from the IDES data in the event that no electric activity develops. The GNC provides optimal cell culture conditions for up to months in combination with full microscopic observability. The 4'' glass wafer technology allows for a high precision of the GNC structures and an economic production of our new system that can be applied in general and developmental toxicity tests as well as in the search for neuro-active compounds.