Cell counting is a procedure with a choice of numerous diverse techniques, most of which rely on specialized laboratory appliances. Despite the variety of cell counters available for modern-day life science applications, they can typically be divided into one of two sub-groups: manual and automated cell counters.
In this blog post, DeNovix compares the benefits of each of these techniques in greater depth.
Manual Cell Counters
The hemocytometer is the slide type most commonly used in manual cell counting. The slide contains a chamber with an etched grid on the lower surface. This device was originally developed for blood sample analysis but is now widely utilized for cell counting and viability analysis for a broad range of mammalian cells.
The microscope slide contains two separate counting chambers that have been etched with a precise grid of exact dimensions. A cover slip is placed on top of the slide to form the top of the counting chamber, setting the depth at a known height. Volume can then be easily calculated.
Manual cell counting can be performed with or without stains. For viability assessment, an exclusion dye such as trypan blue is commonly used. Cells are mixed with the dye and incubated before being pipetted into the measurement chamber.
Once the sample has filled the counting chamber by capillary action, cells can be directly observed using a microscope and counted in specific sectors on the grid. Although it is widely adopted as a method, trypan blue has many well-documented limitations for assessing cell viability. Trypan blue is used to count dead cells; the dye is excluded from cells with intact membranes so only dead cells are stained blue. The process is imperfect and cell color is often difficult to interpret. Consequently, this process is highly subjective. It is also toxic to cells causing changes in viability not related to the health of the sample.
The benefits of manual cell counters are the low initial purchase price and ongoing operating costs, especially when considering the significant cost-increase when it comes to using automated cytometers with single-use plastic slides.
The main drawbacks to manual cell counting are:
- Subjectivity: It requires human interpretation of what are cells and assessment of live/dead cells, causing high error rates between operators.
- Slow: Counting and recording large numbers of cells is a laborious, time-consuming process through which relatively small volumes of cells are counted. Hemocytometers must be thoroughly cleaned between samples.
- Volumetric errors: Pipetting errors and poor siting of the cover slip can lead to measurement inaccuracies.
Automated Cell Counters
Existing automated cell counters have the advantage of largely removing human subjectivity from the cell counting workflow. They are also often faster than counting manually and can count a larger number of cells, increasing statistical accuracy. However, they often fail to justify the cost for cell counting and viability analysis due to high ongoing costs of disposable plastic slides or consumables. DeNovix has developed a proprietary technique for ultra-precise cell counting and viability testing without the requirement of disposable plastic slides. The innovation combines the low cost of manual cell counting with the high speed and high accuracy of automated counts.
CellDrop™ Cell Counters from DeNovix
CellDrop Automated Cell Counters feature a variable height sample chamber formed by two permanent, parallel optical sapphire surfaces. With a high-precision internal mechanism, these surfaces adjust to form a sample chamber with an exact height, eliminating the risk of volumetric errors. The unique DirectPipette™ technology simultaneously resolves the accuracy issues of manual cell counters and the cost-inefficiency and environmental impact of last-generation automated cell counters. Yet the advantages of the CellDrop series go beyond the preparative stage of cell counting. It is equipped with both brightfield and dual fluorescence functionalities, enabling samples to be interrogated with more selective and precise assays alongside simple trypan blue cell viability assessments.
About DeNovix
DeNovix specializes in the development of analytical instruments that deliver high performance, cost efficiency, and a user-friendly interface. The CellDrop Series is the latest entry to a catalog of practical tools designed to ease the challenges facing modern life scientists. The instruments offer significant ongoing cost savings compared to single-use slide technologies and help labs to deliver more environmentally sustainable research. CellDrop also offers improved accuracy and throughput in comparison to manual cell counters.
Follow the links to arrange a demonstration or learn more about CellDrop instrumentation.
