Nowadays, Advanced Therapy Medicinal Products (ATMPs) are new generation of pharmaceuticals which offer novel and revolutionary answer to be given to patients at the end of their therapeutic options. However, because of their prohibitive cost, they can only be proposed to a reduced number of patients. One possibility to reduce ATMP' price is to automate their production as much as possible. Among the numerous possibilities, a real-time and closed loop monitoring of the T-cell growth during the expansion phase would be appreciated. In this short paper, we propose a simple white light spectroscopy method which can be easily implemented in such an autonomous device and able to monitor T-cell number evolution with a higher accuracy as compared to current cell counting methods.

Advanced Therapy Medicinal Products are promising drugs for patients in therapeutic impasses. Their complex fabrication process implies regular quality controls to monitor cell concentration. Among the different methods available, optical techniques offer several advantages. Our study aims to measure cell concentration in real time in a potential closed-loop environment using white light spectroscopy and to test the possibility of simultaneously measuring concentrations of several species. By analyzing the shapes of the absorption spectra, this system allowed the quantification of T-cells with an accuracy of about 3% during 30 h of cultivation monitoring and 26 h of doubling time, coherent with what is expected for normal cell culture. Moreover, our system permitted concentration measurements for two species in reconstructed co-cultures of T-cells and Candida albicans yeasts. This method can now be applied to any single or co-culture, it allows real-time monitoring, and can be easily integrated into a closed system.

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