The new Cellometer Ascend – the better Cellometer
von Christoph Enz
Cell counting is fundamental in cell biology laboratories, yet can be a tedious time-consuming task, prone to the inefficiencies and inaccuracies of manual methods. Accuracy is paramount for maintaining the integrity of downstream workflows, especially within cell therapy research.
It´s been more than 15 years that Nexcelom from Massachusetts (now Revvity) have introduced the first generation of image based automated cell counters. The T4 (initially called M4) was the first of its kind and was a simple bright field counter, paving the way for other more sophisticated family members to come. Fluorescence capabilities enhanced the precision with complex matrices, higher magnifications helped with small cells such as yeast, or platelets. And GLP/CFR compliance was eventually added for regulated environments.
Earlier generations of the Cellometer platform have demonstrated reliable cell counting following the ISO Cell Counting Standards part 1 and 2 (1, 2). They provided cell counts and viability information by use of dual fluorescence and brightfield imaging for nuclei and cell counting, yielding information on cell size, count, concentration, and viability calculations in <60 seconds per sample for various sample types, including cultured cell lines, PBMCs, primary cells, whole blood, and bone marrow.
However, even good things can be improved, and after many thousands of Cellometers and many millions of counts in the cell biology labs of the world, here comes the next generation of automated cell counting with the new Cellometer Ascend.
The Cellometer Ascend goes from fast, simple, precise, and convenient one notch up and further improves the quality of cell counting results. Not surprisingly this means it is considerably faster, even easier to use, offers greater precision specifically at low cell concentrations, and adds flexibility and hence convenience.
And as technology development is not only nice to have, but also an interesting thing to follow, in this blog we dig a little deeper into what drove these improvements and how they were achieved.
So, how do we get from fast, simple, and precise to faster, simpler, and more precise?
Let´s address the speed first. In this department the engineers have brought in various changes, all contributing to the final result of the “faster”.
The Cellometer Ascend comes with a new and much bigger camera sensor chip, bringing obvious reductions in image acquisition time and hence speed. Compared to manual counting a factor of 10 can be achieved. In addition, small tweaks in the handling and software help as well. The measurement starts automatically when a sample slide is inserted and the focus can be found automatically, while high power LED illumination makes sure that exposure times can be kept short.
And “lab speed” is not only the actual measurement in the device, it comprises the entire process from taking a sample out of the fridge to getting a result. For process efficiency with multiple samples the engineers have come up with the new 8-sample slide. This can be loaded in one go, taking a lot of time out of the preparation process, which with older Cellometers used to be one sample at a time. On the 8-sample-slide the spacing is convenient for use with 8-channel pipettes, and after injection these samples are measured without further user intervention. As a result, the overall speed element is most pronounced when it really matters, i.e. when a lot of samples need counting.
And of course, the multi-sample option leads us straight into the “simpler” department. The Ascend is the first integrated-computer cell counter with the new Matrix software and it´s improved workflows compared to the “legacy” Cellometer software, and of course compatible with the Cellometer K2 Matrix and all the Cellaca High Throughput counters.
The novel slide sensing technology with its auto-start feature adds a little bit extra to the overall efficiency, and of course experimental settings can be customized, and commonly used assays can be saved in addition to the pre-configured parameters for over 400 cell types. Built-in predefined protocols include simple things like viability, but also assays for apoptosis, and transfection efficiency. With slide- or image-based focus a choice of two auto-focus methods helps to get the best results for any particular sample and cell type.
In combination all this results in a few clicks less, and a few thoughts saved in everyday routines of any cell biology lab. And probably just “more convenient” than just “simpler”, especially for those working in regulated environments: with the built-in computer the Cellometer Ascend offers Matrix software and it´s CFR21 option without an extra box taking precious lab space.
And the “more precise” brings us back to the bigger camera chip in combination with the bi-directional (x, y) stage movement. Not only does that minimize the actual image acquisition time, with up to eight images per sample it also looks at a larger volume of cell suspension at the same time, which yields substantial improvements in the statistics and hence precision at the lower end of the detectable concentrations (below 2 x 104 cells/ml). And if you think of precious samples of rare primary cells, the enhanced low end lets the Cellometer Ascend work with only 10µm of sample volume. For these measurements focusing on “low end precision” the 3-chamber slides have been developed.
With all that said, and to make it short; it´s not just faster, simpler, and more precise. The Cellometer Ascend is just the better Cellometer. Might be worth checking it out next time you are looking out for cell counting devices.