Reducing the dependency of operator-based counting methods during the manufacturing process of cell and gene therapies

Background & Aim Cell and gene therapy (CGT) manufacturing processes aim to produce therapeutic products with defined characteristics, namely, known cell concentration. Cell counting methods assume special relevance in a clinical setting as specific cell dosages are needed to be met at every stage in the manufacturing process until the administration to the patient. In the past, cell counting methods used were manual-based, time-consuming and lacked in consistency between operators. Here, two automated methods’ accuracy and precision were compared with one manual method. Methods, Results & Conclusion A series of dilution was performed to assess T-cell and mesenchymal stem/stromal cell (MSC) concentration accuracy and precision measured using one manual method (haemocytometer) and two automated methods. The linearity of each counting method in regards to cell concentration was also compared. Additionally, viability and diameter accuracy together with precision across the three different counting systems were also assessed. Regarding cell concentration accuracy, the automated method I was shown to be comparable to the haemocytometer. The reads obtained from the automated method II indicated superior cell concentrations when compared to the haemocytometer, especially for T-cell counts. When assessing linearity, both automated and the manual methods showed similar performance, with the haemocytometer indicating lower linearity values compared to the automated methods. When analysing the viability, differences were also found between the manual and automated methods: the automated methods reported lower viability than the manual method. When precision was assessed, manual methods show to be less precise for determining the cell counts for both cell types. Viability precision was shown to be highly dependent on the cell type. Overall automated methods showed higher precision than the haemocytometer when viability precision assessment was performed