Abstract

CHO cell bioprocessing is a common application for producing biologics, antibodies, and proteins for therapeutic products. One of the most important factors in the CHO bioprocess is the characterization of a cell culture’s concentration and viability to ensure that the cells are in optimal condition for production. Traditionally, CHO cells have been measured using a manual hemocytometer or automated cell counter with trypan blue staining. However, these methods have limitations in throughput and instrument-to-instrument consistency.

Numerous automated cell counting methods have been introduced. To properly compare new cell counting methodologies for introduction into CHO cell bioprocessing, we utilized the recently published ISO cell counting standards (ISO 20391-1:2018 and 20391-2:2019). Under the ISO guidance, since there are no live cell reference standards, metrics other than accuracy may be used to evaluate cell counting methods. These may include linearity, proportionality, precision, and limits of detection. If the performance is fit-for-purpose, factors such as speed, cost, and ease of use may be prioritized. Here, we evaluate the performance of the Cellaca™ MX high-throughput cell counter for implementation into the CHO cell bioprocess. We investigate the precision, instrument-to-instrument consistency, linearity, and proportionality following ISO cell counting standard 20391-2:2019. We demonstrate close agreement between multiple Cellaca™ MX instruments using both CHO cells with Trypan Blue (5 instruments) and beads (32 instruments). We also report system-wide precision, which includes variation between multiple counts, consumables, instruments, and days (in the case of beads). Furthermore, we include the results of several comparison experiments in which samples were counted using Cellaca™ MX, hemocytometer, “Cell Counter V” (a competing instrument), as well as the Celigo® Imaging Cytometer.