Project: General Guidance on Cell Counting

Type: Standards Advancement Project

Partners: ISO/TC 276 U.S. Working Group 3 (US WG3), National Institute of Standards and Technology (NIST), and the SCB Cell Therapy and Tissue Engineering Sector Working Groups


Cell counting is a fundamental measurement that is critical in evaluating the potency and efficacy of cell-based therapies. The cell count (or discrete number of cells) is often expressed as cell concentration (i.e., cell count per volume) when in suspension and as area density of cells (i.e., cell count per unit area) when adhered to a surface. Developing standards for cell counting will allow more precise and consistent measurements, better equipping researchers and product developers to use cell counts as a quality assurance metric or for normalization of cell-based bioassays to compare different data sets.

SCB is supporting the development of a two-part ISO documentary standard on cell counting. Part 1 of the standard (published January 2018) defines terms and provides general guidance for cell counting measurement processes, including method selection, sample preparation, measurement, qualification and validation, and data analysis and reporting. Part 2 will provide a method that can be used for evaluating specific aspects of the quality of a cell counting measurement process.


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Supporting Draft Development: SCB has helped NIST coordinate the development of ISO/FDIS 20391‑2: Cell counting -- Part 2: Experimental Design and Statistical Analysis to Quantify Counting Method Performance.

Soliciting Comments Through ISO Ballot: Part 2 of the Draft International Standard (DIS) was open for ballot from November 2018 to February 2019. The draft was approved in June 2019 and is expected to be published in October 2019.

Supporting Education and Outreach: SCB has helped to make information about the publication of Part 1 of this document more accessible through multiple methods, including newsletters, sector calls, social media, and the SCB website.

Get Engaged:

To learn more about this initiative, please contact SCB.