Acrylic Biochemistry Dual Channel System

Introduction 

The Dual Cell Slice Chamber is a tissue slice chamber that can be used in both submerged or interface modes. It contains six independent channels – two acrylic tissue cell bodies for tissue biochemistry and four holding compartments for keeping cells alive until needed. However, it is also available with four or six test cells. The ability to work with multiple slices simultaneously makes the chamber time-efficient. 

In interface-type chambers, tissue slices are held on a nylon mesh at the interface between artificial fluid and humidified gas (a combination of 95% O2/5% CO2), allowing for the preservation of live cells and their microcircuits in hundreds of micrometer-thick slices for a few hours. The flow rate of fluid is often kept low, about 1 ml/min. Therefore, the full effects of hydrophobic pharmacological substances will take at least 30 minutes of perfusion to allow the drug to reach the slice and diffuse slowly into the tissue. On the other hand, in submerged chambers, gas and nutrients are delivered to the slices through the artificial fluid, with typical flow rates of 2–3 ml/min. The quicker exchange of pharmacological substances is made possible by the considerably greater flow velocity and the submerged nature of the slices (Hájos & Mody, 2009). Both modes have their advantages and limitations; however, the Dual Cell Slice Chamber operates in either mode, which helps fit several experimental needs. 

The acrylic cell body of the Dual Cell Slice Chamber absorbs pharmacological manipulations and releases them later. Both modes have a stable, linear flow of temperature. The chamber includes a digital display heater/controller device with predictive algorithms and dual feedback from a thermistor for quick feedback and another for spot temperature offset. The water bath temperature is also controlled between +/- 01 Celsius. No reference electrode is included with the chamber, so it is not suitable for electrophysiology. 

Apparatus and Equipment 

The Dual Cell Slice Chamber consists of two acrylic tissue cell bodies and four holding compartments. It is equipped with a heater/controller device with predictive algorithms and dual feedback from a thermistor. The chamber provides a stable, linear flow of temperature. The temperature of the water bath is controlled between +/- 01 Celsius. 

Literature Review 

Investigation of hypoxia tolerance in naked mole rats

Larson and Park (2009) investigated the effect of hypoxia on the brain tissue of naked mole rats by analyzing evoked responses by hippocampal slices using an interface slice chamber. The brain slices were put in the chamber and continuously perfused with artificial cerebrospinal fluid (ACSF) (1.0 ml/min) at 30 or 35 degrees Celsius. Hypoxia was established by replacing the O2 content of the chamber atmosphere and perfusion ACSF with different nitrogen concentrations (N2). Results indicated that the rodents’ brain tissue was extraordinarily resistant to hypoxia, despite being in a continuously low-oxygen environment.

Assessing invasion of glioma cells in mammalian brains 

The Dual Cell Slice Chamber can be used to assess the invasion of glioma cells in mammalian brains. Schichor et. al (2005) used a brain slice chamber to evaluate glioma cell invasion into adult mammalian white and grey matter in vitro. They provided quantitative and morphological data on the interaction between glioma cells and white matter. The chamber was used to retain the slice’s neuronal structures and three-dimensional architecture. During a 24 hour period, astrocytoma cells were transfected with green fluorescent protein (GFP) and evaluated for their invasiveness into the brain slices. Results indicated that the glioma cells invaded the white matter more intensely than the grey matter. 

Investigation of the role of mitochondrial superoxide in synaptic plasticity, aging, and memory-associated behavior

Hu et al. (2007) investigated the role of mitochondrial superoxide in synaptic plasticity, aging, and memory-associated behavior in transgenic mice overexpressing mitochondrial superoxide dismutase (SOD-2 or Mn-SOD). An interface tissue slice chamber was used to perfuse the brain slices with oxygenated artificial cerebrospinal fluid (ACSF) for one to two hours at 30 to 32 degrees Celsius. The basal synaptic transmission (input/output) and paired-pulse facilitation were examined. Results indicated that the overexpression of SOD-2 showed no effect on synaptic plasticity or memory formation in young mice. Moreover, it was unable to reverse age-related deficiencies in synaptic plasticity or memory in old mice. 

Investigation of the effect of drugs using cardiac tissue slices of rodents 

Bussek et al. (2012) utilized cardiac tissue slices from rodents to assess the effect of drugs over three consecutive days after keeping the slices under appropriate cardioplegic conditions using a tissue slice chamber. The tissue slices were preserved in the chamber and superfused with oxygenated Tyrode’s solution (2 ml/min) at 34°C continuously. One concentration of the drugs was added to the superfusion solution every 30 minutes. Electrophysiology of the slices was also conducted in the chamber to record extracellular field potentials (FP) and intracellular action potentials (AP). The drug effects on FP and AP duration and latency were monitored to assess the viability of the slices on consecutive days after preparation. It was observed that the FP and AP duration significantly increased in the presence of the potassium channel blocker E403. These changes were also observed 24 to 28 hours after the slice preparation. FP and AP parameters were also affected by calcium channel blocker nifedipine (10 μM), potassium channel blocker 4-aminopyridine (30 mM), and gap junction blocker carbenoxolone (30 μM), whose changes were also evident hours after slice preparation. Therefore, the results of this study indicated that freshly isolated cardiac slices could be used for more than 24 hours after preparation for studying physiological and pharmacological responses to drug administration. 

Strengths and Limitations 

The Dual Cell Slice Chamber allows the preservation of tissue slices in both interface and submerged modes, making it applicable for several experimental purposes. It can be used to preserve tissue slices from different organs for drug screening, hypoxia tolerance, glioma invasion, and other physiological parameters. It comprises two acrylic cell bodies and four holding cells, allowing multiple slices to be preserved and analyzed at the same time. The acrylic cell body absorbs pharmacological manipulations and releases them later. The chamber is temperature regulated and also provides predictive algorithms for temperature. The only limitation of the dual cell slice chamber is that it is not equipped with electrodes, so it is not suitable for experiments involving electrophysiology. 

Summary 

1. The Dual Cell Slice Chamber is a tissue slice chamber that can be used in both submerged or interface modes.
2. It contains six independent channels – two acrylic tissue cell bodies for tissue biochemistry and four holding compartments for keeping cells alive until needed.
3. The chamber is temperature regulated in both modes. 
4. It can be used to preserve tissue slices from different organs for drug screening, hypoxia tolerance, glioma invasion, and other physiological parameters.
5. No reference electrode is included with the chamber, so it is not suitable for electrophysiology.

References 

1. Hájos, N., & Mody, I. (2009). Establishing a physiological environment for visualized in vitro brain slice recordings by increasing oxygen supply and modifying aCSF content. Journal of neuroscience methods, 183(2), 107–113. https://doi.org/10.1016/j.jneumeth.2009.06.005
2. Bussek, A., Schmidt, M., Bauriedl, J., Ravens, U., Wettwer, E., & Lohmann, H. (2012). Cardiac tissue slices with prolonged survival for in vitro drug safety screening. Journal of pharmacological and toxicological methods, 66(2), 145–151. https://doi.org/10.1016/j.vascn.2011.12.002
3. Larson, J., & Park, T. J. (2009). Extreme hypoxia tolerance of naked mole-rat brain. Neuroreport, 20(18), 1634–1637. https://doi.org/10.1097/WNR.0b013e32833370cf
4. Schichor, C., Kerkau, S., Visted, T., Martini, R., Bjerkvig, R., Tonn, J. C., & Goldbrunner, R. (2005). The brain slice chamber, a novel variation of the Boyden Chamber Assay, allows time-dependent quantification of glioma invasion into mammalian brain in vitro. Journal of neuro-oncology, 73(1), 9–18. https://doi.org/10.1007/s11060-004-3341-3
5. Hu, D., Cao, P., Thiels, E., Chu, C. T., Wu, G. Y., Oury, T. D., & Klann, E. (2007). Hippocampal long-term potentiation, memory, and longevity in mice that overexpress mitochondrial superoxide dismutase. Neurobiology of learning and memory, 87(3), 372–384. https://doi.org/10.1016/j.nlm.2006.10.003