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LeviCell Technology: Cell Separation, Principles, and Applications
Frequently Asked Questions about LeviCell Technology
1. What is the main principle behind LeviCell technology?
LeviCell technology uses a magnetic field and a paramagnetic levitation agent to separate cells based on their intrinsic physical properties, primarily density and magnetic susceptibility. Cells are loaded into a single-use cartridge and exposed to the magnetic field, where they levitate to different heights depending on these properties, enabling label-free separation and enrichment.
2. What are some user-modifiable parameters in the LeviCell system and how do they affect cell levitation?
User-modifiable parameters include:
- Levitation Agent (LA) Concentration: Adjusting the concentration of LA influences the levitation height of cells. Higher concentrations generally result in tighter cell bands and faster levitation, and can sometimes improve the separation of distinct cell types. Typical concentrations range from 50 mM to 150 mM.
- Cell Concentration: The number of cells loaded into the cartridge affects band appearance at final levitation height. It's recommended to start with 250,000 cells when testing a new cell type, avoiding more than 1 million cells to distinguish live and dead cell bands clearly. Larger cells (>20 μm) require lower cell numbers due to space limitations within the chamber.
- Levitation Time: The time required for cells to reach their final levitation height varies depending on cell size, from 5 minutes for very large cells to 40 minutes for smaller cells. A minimum of 20 minutes is recommended when evaluating a new cell or sample type to allow dead cells to fully separate
- Split Line: The split line determines which cells are collected. Care should be taken when working with heterogenous samples, like PBMCs or dissociated tissue, to ensure target cell types are not inadvertently excluded from collection.
3. What is the role of the Levitation Agent in the LeviCell system?
The Levitation Agent (LA) is a paramagnetic compound added to the cell suspension media. It interacts with the magnetic field to create a density gradient within the separation channel. Cells then levitate within this gradient based on their own density and magnetic properties. The LA is preferentially taken up by non-viable cells, creating a clear distinction in levitation height between viable and non-viable cells and facilitating viable cell enrichment.
4. What types of samples can be processed using the LeviCell system?
The LeviCell system is versatile and can process a wide range of sample types, including:
- Dissociated primary tissues (brain, lung, liver, tumor)
- Peripheral Blood Mononuclear Cells (PBMCs)
- Cell lines (e.g., Jurkat, H358)
- Organoids
The system is designed to handle challenging samples with low viability or purity, and it's particularly well-suited for sensitive cell types.
5. How does LeviCell technology compare to traditional cell sorting methods like FACS?
LeviCell offers several advantages over traditional FACS sorting:
- Label-free and bias-free: LeviCell doesn't require cell staining or surface markers, preserving the native state of the cells and avoiding potential alterations in gene expression.
- Gentle processing: The LeviCell instrument operates at very low pressure (<1 PSI), minimizing cell damage and stress compared to FACS (which starts at 30 PSI).
- Enhanced Viability: LeviCell has been shown to improve cell viability, particularly in cryopreserved or low-quality samples.
- Reduced Ambient RNA: LeviCell enrichment results in less ambient RNA contamination, leading to better data quality in downstream applications like scRNA-seq.
- Simplified Workflow: Certain LeviSelect kits remove the need for centrifugation and extra wash steps.
6. What are LeviPrep and LeviSelect products, and how do they work with the LeviCell system
- LeviPrep: LeviPrep products are tissue dissociation kits designed to provide a fast and easy method for generating single-cell suspensions from primary tissues. The kits use a cold dissociation protocol to minimize transcriptional changes and preserve cell health. Different enzyme combinations are available to optimize dissociation for specific tissues like brain, liver, and lung.
- LeviSelect: LeviSelect products combine Levitation Technology with target selection of specific cell types. These kits enable the depletion of unwanted cells (e.g., CD45+ immune cells) or the enrichment of target cells (e.g. T cells, B cells, Monocytes, NK cells) by modulating their magnetic properties using magnetic nanospheres conjugated with antibodies. This allows for simultaneous viable cell enrichment and specific cell population selection.
7. What applications is the LeviCell system suitable for?
The LeviCell system is suitable for a wide range of applications, including:
- Single-cell RNA sequencing (scRNA-seq)
- Immunology research
- Oncology research (tumor cell enrichment, immune cell depletion)
- Neuroscience research (microglia isolation, brain cell analysis)
- Organoid research
- Drug discovery and development
The system is particularly useful when working with precious, rare, or sensitive samples where preserving cell viability and native state is crucial.
8. What visualization capabilities does the LeviCell system offer?
The LeviCell platform provides real-time visualization of samples using brightfield microscopy and optional green and red fluorescence channels. This allows users to:
- Monitor cell levitation behavior
- Identify specific cell populations based on staining or innate fluorescence (e.g., GFP-expressing cells)
- Assess sample quality before downstream analysis
- Troubleshoot separation issues
- Track the success of transfection protocols
- Visualize morphological differences or marker expression
The system captures images every 3 seconds, and these images can be used to create movies or panoramic views of the levitation process using the Experiment Analyzer software.