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Maestro Systems with AxIS
Developing advanced electrically active cell models is challenging. Are gene expression, FACS, or Western blots enough to capture the complexity of your stem-cell derived neurons and cardiomyocytes? The cells may have the proper characteristics,but how do they function in a network?
Enter Maestro microelectrode array (MEA), the multiwell in vitro platform that provides you with the cell activity information you've been missing. Now you can track the differentiation of electroactive cells (e.g. neurons, cardiomyocytes, and muscle cells) label-free in real-time with the Maestro multiwell activity map. Over minutes or months, gain unprecedented access to electrical network function from cultured cell populations. Straightforward and easy to use, the Maestro can measure activity from electroactive cells in 12-, 24-, 48-, or 96-well plates.
Maestro Systems workflow
Preparing sufficient cell material for down-stream analysis often involves performing the cell differentiation process in tissue culture flasks. This approach consumes excessive, often expensive reagents, and limits the number of experimental variables that can be comfortably tested.
Maestro's label-free and non-invasive technology enables multiple recordings over time from the same population of cells. Take a snapshot of cell activity at a single time point or monitor a population's maturity over weeks or months.
This means reduced cell reagent costs in a convenient multi-well plate format, enabling users to explore many more experimental conditions and collect more replicate data points than ever before.
Track excitable cell differentiation in 96-well MEA plates
Measure what matters – indirect measures of cell quality are regularly used to track stem cell differentiation efficiency. However, expression levels of protein markers often poorly correlate with cell model performance. For example, Myosin Heavy Chain (MHC) expression in hiPSC-cardiomyocytes is a poor predictor of spontaneous cardiomyocyte beating. Maestro tracks cell excitability in real-time enabling you to measure what matters: do your hiPSC-cardiomyocytes spontaneously beat, or do your hiPSC-neurons fire as expected?
Analyze cell activity label-free – Maestro performs noninvasive electrical measurements from the cultured cell population. MEA recordings do not consume cells, and multiple measurements can be acquired from the same population of cells. Multiple recordings from the same cells alleviates concerns of having to link datasets from disparate time-points.
Probe cell models in the same plate they were differentiated in – platforms that measure cell quality (e.g. flow cytometry) often require cell samples to be transferred into a single-cell suspension before testing. This requirement is far from ideal since  excitable cells exist as a functional network of inter-linked cells, and  the cell harvesting process requires numerous handling steps. Maestro probes your electrically active cell models whilst preserving the morphological complexity sought from your differentiation process. Additionally, the reduced handling steps of the Maestro approach save you both time and resources.
Human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) are an attractive model for studying heritable and drug-acquired arrhythmias. The ability to efficiently produce multiple patient-derived hPSC-CMs and easily track their excitability performance during differentiation is desirable. This would facilitate the determination of the effect of genetic diversity on drug-acquired arrhythmias between multiple different hPSC-CM lines. In pursuit of this objective, hPSC differentiation into cardiomyocytes using the STEMdiff™ Cardiomyocyte Differentiation and Maintenance Kits (STEMCELL Technologies) was tracked each day using the Maestro MEA system.
PSCs were seeded as single cells (~0.9x105/well) with Y-27632 ROCK inhibitor in TeSR™-E8™ or mTeSR™1 medium on Matrigel®-coated well of a 48-well CytoView™ plate (Day -2). The PSCs were maintained with daily medium without Y-27632 (Day -1) until a confluent monolayer (>95%) was achieved (Day 0). The confluent monolayers of hPSCs were differentiated to cardiomyocytes using the STEMDiff™ Cardiomyocyte Differentiation Kit. At Day 0, the cells were treated with differentiation medium A. Day 2, medium A was removed and replaced with differentiation medium B. Day 4, medium B was removed and replaced with differentiation medium C. Day 6, medium C was removed and replaced with fresh differentiation medium C. Day 8, medium C was removed and replaced with maintenance medium. Thereafter, the maintenance medium was removed and replaced with fresh maintenance medium every 2 days until Day 15. At Day 15 cardiomyocytes were maintained with daily medium changes until Day 26 using the STEMdiff™ Cardiomyocyte Maintenance Kit. MEA recordings (5 minutes) were taken daily until Day 26 using the Maestro MEA system. On Day 26, 10 nM E-4031 was added for 10 minutes . MEA recordings were analyzed using the AxIS software.
Functional Data Cardiomyocytes
[A] Maestro activity map showing 12 wells of a CytoView MEA 48 well plate (i.e. 16 electrodes per well). Spontaneous cardiomyocyte activity was first detected on Day 14 of the STEMdiff™ Cardiomyocyte Differentiation Kit protocol, and this developed over time to be maximal by Day 25.
[B] The number of wells detecting beating increased gradually over time, suggesting the cell monolayer became electrically coupled as it matured. However, the field potential duration (FPD; related to the duration of cardiomyocyte excitability) remained consistent as the cells matured (203.1 +/- 42.7 ms).
[C] Representative MEA electrophysiological recording of the hPSC-CM spontaneous activity before (black) and after (red) applying 10 nM E-4031 (10 min), a hERG K+ channel blocker. As expected, E-4031 prolonged the measured FPD.
STEMdiff™ Cardiomyocyte Differentiation and Maintenance Kits reliably differentiated hPSCs into beating monolayers of cardiomyocytes by Day 15, with stable excitability profiles observed by Day 21.
The resulting hPSC-CMs can be challenged with test compounds in the same MEA plate they were differentiated and maintained in.
The Maestro MEA System and STEMdiff™ Cardiomyocyte Differentiation and Maintenance Kits support medium to high throughput drug discovery and toxicology screening using multiple genetically diverse hPSC-derived cardiomyocytes in a label-free manner.
Data courtesy of STEMCELL Technologies, taken from Marci et al. 2017 presented at ISSCR2017.
Action potential firing and synaptic activity are fundamental properties of neurons in the brain. Bardy et al. (PNAS, 2015) have recently reported that Neurobasal® Medium and DMEM/F-12 support neuron survival but suppress their synaptic activities in culture. Since for most studies it is desirable for human pluripotent stem cell (hPSC)-derived neurons to have spontaneous electrical activity, an improved neural differentiation and culture medium, BrainPhys™ Neuronal Medium, was developed. Here the effect of BrainPhys™ and DMEM/F-12 based media on the synaptic activity of hPSC-derived neurons during 18 week in culture was tested.
Neural progenitor cells derived from hPSCs (XCL1-NPC) were cultured in STEMdiff™ Neuron Differentiation Medium on poly-L-ornithine (PLO)/laminin-coated 6-well plate for 5 days. On day 5, neural progenitor cells were dissociated and single cells were re-plated onto a PLO/laminin-coated CytoView MEA 12 plate at 30,000 cells/cm2 in STEMdiff™ Neuron Differentiation Medium. After one day, half of the medium was replaced with differentiation media, (DMEM/F-12, DMEM/F-12/NB-A [DMEM/F-12 and Neurobasal-A mixed in a 1:1 ratio], or BrainPhys™ Neuronal Medium + supplements: 1% N2 Supplement-A, 2% NeuroCult™ SM1 Neuronal Supplement, 20 ng/mL GDNF, 20 ng/mL BDNF, 1 mM db-cAMP and 200 nM Ascorbic Acid). Half-medium changes were performed every 3 - 4 days throughout the culture period. Spontaneous neuronal activity was acquired at 37°C under a 5% CO₂ atmosphere using the Maestro MEA system. A 15-minute recording was taken twice a week and analyzed using AxIS software.
BrainPhys functional data
[A] Raster plots showing the firing patterns of neurons across 64 electrodes in a well of the 12-well MEA plate after 18 weeks in culture. Each black line represents a detected spike. Blue lines represent single channel bursts - a collection of at least 5 spikes, each separated by an inter-spike interval (ISI) of no more than 100 ms. Network bursts are marked with purple boxes and are defined as a collection of at least 10 spikes from a minimum of 25% of participating electrodes across the entire well, each separated by an ISI of no more than 100 ms. Neurons cultured in BrainPhys™ demonstrated improved electrical activity compared to DMEM/F-12/NB-A media as shown by the increased number of spikes (neuronal activity) over time.
[B] Network bursts were first detected at week 6 in BrainPhys™ and DMEM/F-12/NB-A conditions. The number of network bursts increased gradually over time, suggesting that both cultures became more synchronous as they matured. After 18 weeks in culture, the number of network bursts detected in a 10-minute recording in BrainPhys™ and DMEM/F-12/NB-A were 114 and 54, respectively, indicating that a synchronous neuronal network was developed more efficiently in BrainPhys™.
- Neurons cultured in BrainPhys™ Neuronal Medium exhibit improved electrical activity and develop synchronous network activity over time based on MEA data.
Data courtesy of STEMCELL Technologies, taken from Mak et al. 2016 presented at SfN2016.