Major advances in biologics production, cell and gene therapy, and regenerative medicine have prompted the need for highly accurate cell characterization. Also, the varying complexities of biological sources involved in these revolutionary studies and treatments require different optimized conditions, formulations, and bioprocessing steps depending on the intended use.

To help address these challenges, cell counting experts at Nexcelom, now part of Revvity, have identified six key points to increase the confidence of cell counting results involving the selection of source materials, methodologies, and instrumentation based on the specific cell requirements and the desired data readout.

Achieving accurate cell counts, viability percentages, and biomarker measurements starts with selecting and evaluating the appropriate cell counting method. This method selection includes deciding the correct cell counting assay, reagents, consumables, and software analysis needed for a particular cell type. 
When looking to validate cell counting methods for pre-clinical trials, clinical trials, and process development, the International Organization for Standardization (ISO) Cell Counting Standards Part 1 and 2 provide a framework for evaluating the performance of any cell counting method.

Navigating cell counting method selection

Revvity recognizes the significance of assisting researchers in applying the ISO Cell Counting Standards to their workflows and have highlighted the factors that can influence the quality of the cell counting results.

Through customer collaborations and internal studies, the Research and Development team developed strategies based on the ISO standards to create a Practical Cell Counting Method Selection Guide to Increase the Quality of Cell Counting Results. These considerations allow researchers to easily adhere to the ISO recommendations and ensure high-quality cell counting measurements.

Six key factors impacting the selection of cell counting methods and the quality of cell counting measurements:

1. Determine the desired information needed from the cell counting result (to ensure it is fit-for-purpose), such as tumor digestion for single cell-based transcriptome analysis, mouse tissue processing for cytotoxicity assays, or isolation of human PBMCs for immunophenotyping analysis, etc.
2. Investigate cell sample composition and morphology, where it is important to know the cell composition (various cell types, particle debris, chemical impurities, and suspension medium), as well as their visual appearances.
3. Select the appropriate cell counting assay principle for the intended result, such as total, live, dead cell count, viability, or cell population analysis.
4. Investigate instrument capabilities and select the appropriate cell counting system, where the system consists of reagents, consumables, instruments, and software algorithms.
5. Consider all aspects of the cell counting process including preparatory steps, including sampling, diluting, and staining, which are all critical for proper sample preparation.
6. Regularly refresh knowledge base and operational training, to ensure consistent cell counting results.

References:

1. International Organization for Standardization (ISO). ISO Cell Counting Standard Part 1. ISO 20391-1:2018 Biotechnology – Cell counting – Part 1: General guidance on cell counting methods. ISO Cell Counting Standard Part 2. ISO 20391-2:2019 Biotechnology – Cell counting – Part 2: Experimental design and statistical analysis to quantify counting method performance
2. Practical application of cell counting method performance evaluation and comparison derived from the ISO Cell Counting Standards Part 1 and 2.  Y Huang, J Bell, D Kuksin, S Sarkar, LT Pierce, D Newton, J Qiu & LLY Chan. Cell & Gene Therapy Insights 2021; 7(9), 937–960 (DOI: 10.18609/cgti.2021.126)
3. Practical Cell Counting Method Selection to Increase the Quality of Cell Counting Results Based on ISO Cell Counting Standards Part I 

For research use only. Not for use in diagnostic procedures.