Electromagnetic exposure of scaffold-free three-dimensional cell culture systems

Daus, Andreas W.; Goldhammer, Michael; Layer, Paul G.; Thielemann, Christiane

doi:10.1002/bem.20649

Cited by 19 publications

(10 citation statements)

References 41 publications

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“…placing the Petri dishes on a gyratory shaker (72 rpm) within an incubator (37 • C, 5% CO 2 ) (Daus et al, 2011). The resulting spheroids were then plated on microelectrode arrays (MEA; Multichannel Systems, Reutlingen, Germany) for extracellular recording.…”

Section: Classesmentioning

confidence: 99%

A novel automated spike sorting algorithm with adaptable feature extraction

Bestel

Daus

Thielemann

2012

Journal of Neuroscience Methods

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To study the electrophysiological properties of neuronal networks, in vitro studies based on microelectrode arrays have become a viable tool for analysis. Although in constant progress, a challenging task still remains in this area: the development of an efficient spike sorting algorithm that allows an accurate signal analysis at the single-cell level. Most sorting algorithms currently available only extract a specific feature type, such as the principal components or Wavelet coefficients of the measured spike signals in order to separate different spike shapes generated by different neurons. However, due to the great variety in the obtained spike shapes, the derivation of an optimal feature set is still a very complex issue that current algorithms struggle with. To address this problem, we propose a novel algorithm that (i) extracts a variety of geometric, Wavelet and principal component-based features and (ii) automatically derives a feature subset, most suitable for sorting an individual set of spike signals. Thus, there is a new approach that evaluates the probability distribution of the obtained spike features and consequently determines the candidates most suitable for the actual spike sorting. These candidates can be formed into an individually adjusted set of spike features, allowing a separation of the various shapes present in the obtained neuronal signal by a subsequent expectation maximisation clustering algorithm. Test results with simulated data files and data obtained from chick embryonic neurons cultured on microelectrode arrays showed an excellent classification result, indicating the superior performance of the described algorithm approach.

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Section: Classesmentioning

confidence: 99%

A novel automated spike sorting algorithm with adaptable feature extraction

Bestel

Daus

Thielemann

2012

Journal of Neuroscience Methods

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“…), they express a number of physiological characteristics and resemble more closely the native tissue from which they originated than the same cells grown in classical two-dimensional (2D) culture flasks. The reason for this has been suggested to be related to the fact that 3D cell culture allows the cells to develop a more elaborate extracellular matrix and better intercellular communication (Daus et al , 2011; Lin et al , 2006; Loessner et al , 2010), and this leads to a recovery or maintenance of in vivo function (Selden et al , 2000). Three-dimensional (3D) structure has therefore been proposed as the missing link, which will provide in vitro models that sufficiently mimic in vivo conditions (Griffith and Swartz, 2006; Nelson et al , 2010; Pampaloni et al , 2007).…”

mentioning

confidence: 99%

Determination of Drug Toxicity Using 3D Spheroids Constructed From an Immortal Human Hepatocyte Cell Line

Fey

Wrzesinski

2012

Toxicological Sciences

161

157

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Numerous publications have documented that the immortal cells grown in three-dimensional (3D) cultures possess physiological behavior, which is more reminiscent of their parental organ than when the same cells are cultivated using classical two-dimensional (2D) culture techniques. The goal of this study was to investigate whether this observation could be extended to the determination of LD50 values and whether 3D data could be correlated to in vivo observations. We developed a noninvasive means to estimate the amount of protein present in a 3D spheroid from it is planar area (± 21%) so that a precise dose can be provided in a manner similar to in vivo studies. This avoided correction of the actual dose given based on a protein determination after treatment (when some cells may have lysed). Conversion of published in vitro LC50 data (mM) for six common drugs (acetaminophen, amiodarone, diclofenac, metformin, phenformin, and valproic acid) to LD50 data (mg compound/mg cellular protein) showed that the variation in LD50 values was generally less than that suggested by the original LC50 data. Toxicological analysis of these six compounds in 3D spheroid culture (either published or presented here) demonstrated similar LD50 values. Although in vitro 2D HepG2 data showed a poor correlation, the primary hepatocyte and 3D spheroid data resulted in a much higher degree of correlation with in vivo lethal blood plasma levels. These results corroborate that 3D hepatocyte cultures are significantly different from 2D cultures and are more representative of the liver in vivo.

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“…The preparation of cardiac myocytes was carried out following a modified protocol of Daus and Thielemann [6]. Fertile chicken eggs (white Leghorn) were incubated at 37°C in a surface breeder (Bruja 3000, BrutmaschinenJaneschitz GmbH, Hammelburg, Germany).…”

Section: Cell Culturementioning

confidence: 99%

Three-Dimensional Carbon Nanotube Electrodes for Extracellular Recording of Cardiac Myocytes

et al. 2012

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Low impedance at the interface between tissue and conducting electrodes is of utmost importance for the electrical recording or stimulation of heart and brain tissue. A common way to improve the cell-metal interface and thus the signal-to-noise ratio of recordings, as well as the charge transfer for stimulation applications, is to increase the electrochemically active electrode surface area. In this paper, we propose a method to decrease the impedance of microelectrodes by the introduction of carbon nanotubes (CNTs), offering an extremely rough surface. In a multistage process, an array of multiple microelectrodes covered with high quality, tightly bound CNTs was realized. It is shown by impedance spectroscopy and cardiac myocyte recordings that the transducer properties of the carbon nanotube electrodes are superior to conventional gold and titanium nitride electrodes. These findings will be favorable for any kind of implantable heart electrodes and electrophysiology in cardiac myocyte cultures.

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Electromagnetic exposure of scaffold-free three-dimensional cell culture systems

Cited by 19 publications

References 41 publications

A novel automated spike sorting algorithm with adaptable feature extraction

A novel automated spike sorting algorithm with adaptable feature extraction

Determination of Drug Toxicity Using 3D Spheroids Constructed From an Immortal Human Hepatocyte Cell Line

Three-Dimensional Carbon Nanotube Electrodes for Extracellular Recording of Cardiac Myocytes

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