Flow cytometry (FCM) is a method used to detect and measure cell biology of a cell population or a group of particles. It is most often used in the biosciences. Analysis requires a sample that contains the particles or cells suspended in a fluid. The fluid is injected into a flow cytometer, where it is focused to move through a laser beam one cell at a time. The light scattered is related to the characteristics of cells and their components. Cells are often marked with fluorescent dyes to absorb light that’s then emitted in a wavelength band. Flow cytometers can examine tens of thousands of cells in a short period of time. After data acquisition is complete, it’s processed by a computer.
Types of Flow Cytometers & Their Uses
Though there are many types of flow cytometers, benchtop instruments are the primary choice. There are upgrades and options available for the different systems, tailored to address customized separations, cell/particle sorting, exploratory cell analysis, and more.
All flow cytometers feature three common components – fluids, optics, and electronics/informatics.
Fluidics takes the solution of cells and converts them into a stream for analysis. Most often, the stream is focused using hydrodynamic focusing, where a nozzle ejects the cell solution through a stream of sheath fluid. That sheath fluid drag effect basically thins the solution so that the cells suspended in the solution line up single-file. It’s possible to adjust the speed of the sheath fluid in order to adjust the stream width. A faster sheath fluid speed creates a narrower stream, increasing the chance that cells will move one at a time through the detector. This makes it easier for the cell analyzer to look at single cells.
The optics rely on lasers to excite the molecules and collection optics like photodiodes, or photomultiplier tubes (PMT), to generate the light used to analyze the sample. Flow systems monitor two measurements of light scatter – forward scatter light (FSC) and side scatter light (SSC). These provide information on the cell’s complexity – such as the cell surface granularity and the presence of an internal structure. Light scatter patterns only provide information on the physical properties of a cell. To learn more about the molecular characteristics, the cells need to be tagged. This is generally done using fluorophores or fluorescent-tagged nanoparticles or antibodies. Several optical filter options are available as well – bandpass, long pass, or short pass. These filters only allow the transmission of emission spectra either within a wavelength range (bandpass filters), or above (long pass) or below (short pass) a specific wavelength.
The electronics and informatics convert the signals from the detectors into digital signals so the computer can read them.
Beyond the traditional flow cytometer, there are:
- Acoustic focusing cytometers: These cytometers use ultrasonic waves to improve focus cells for laser interrogation. These models allow for higher sample inputs without increasing the risk of sample clogging. With these high-performance instruments, it’s possible to use up to four lasers and 14 fluorescence channels.
- Cell sorters: These purify and collect samples for additional analysis. The cell sorter allows the user to choose a population of cells or particles for the intended parameters and then direct the cells to the collection vessel. Then, the cells are separated by oscillating the sample stream of liquid at a high frequency so it forms drops. The drops are then charged and passed through metal plates where they’re directed to a particular collection vessel based on their charge. There are two types of cell sorters to choose from, jet-in-the-air and quartz cuvette. The difference is where the laser interrogation point is found on the machine.
- Imaging cytometers: IFCs offer a combination of flow cytometry and fluorescence microscopy. These instruments generally have the PMT replaced with a charge-coupled device (CCD) camera. In addition to identifying the fluorescent markers and their intensity within a cell population, these can be helpful in monitoring experiments, like cell signaling and protein translocation.
- Mass cytometers: These units combine time-of-flight mass spectrometry with flow cytometry.
There are many applications for cytometry such as:
- Cell-cycle analysis
- Cell imaging
- Cell proliferation
- Cell signaling
- Cell death
- Plant ploidy
- Stem cell research
Average Flow Cytometer Costs
Pricing for flow cytometer systems varies widely, depending on the components that are on the system and its features. When choosing the systems for your new lab, consider the total cost per experimental run, and how frequently you’ll need to perform cell separation and characterization experiments. Some manufacturers, such as Sony, are beginning to build flow cytometer instruments that cost under $100,000, but it’s still possible to spend anywhere from $100,000 to $500,000 for a single unit.
Popular models are the BD Biosciences Accuri C6, EasyCyte, CytoFLEX from Beckman Coulter, FACSCanto II, and Attune’s acoustic focusing cytometer. Newer instruments use software to automate a number of processes, not only improving usability but helping to bring costs down.
It’s important for a laboratory to research which type of flow cytometer is best suited for their needs so that they do not overspend on components and features that they can’t utilize.
Leasing vs. Buying Flow Cytometers
For the startup lab, it may seem like purchasing a used or refurbished machine could be a decent way to stretch the budget. While it will cost less upfront than purchasing a brand new unit, there are still costs associated with maintenance and repair. If the condition of the unit isn’t what you expect, it could lead to unexpected costs and downtime.
Leasing your lab equipment, however, means you spend even less upfront while still getting access to all the machines you need in your lab. You’ll save more in the long run because maintenance and repair are covered in the cost of the lease, and you can reinvest your extra capital in your operations or business development needs. Contact us to learn more about how Excedr’s leasing options can help you.