White light spectroscopy for T-cell culture growth monitoring: towards a real-time and sampling free device for ATMPs production

Abstract

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.

Absorption Spectra Description for T-Cell Concentrations Determination and Simultaneous Measurements of Species during Co-Cultures

“…In the Beer–Lambert derived model [ 30 ], the value of the maxima of each spectrum was used to compute the corresponding concentration, but this model cannot be used to simultaneously compute concentrations of species within a mixture. Here, the information contained in the whole absorption spectrum was exploited to establish a model describing the evolution of CEM absorption spectra with the concentration.…”

“…The spectra shape model calculated an initial CEM concentration of 4.6 × 10 5 cells.mL −1 while the cuvette was initially filled with a concentration of 5 × 10 5 cells.mL −1 . This value was correct, especially considering that the cell counter measurements were not fully representative of the real concentration within the culture flask (see Discussion and [ 30 ]).…”

“…Spectral absorption measurements of CEM suspensions were performed using the experimental setup shown in Figure 1 (adapted from [ 30 ]). The spectroscopy measuring system consists of a light source (AvaLight-DH-S-BAL, Avantes ® , the Netherlands, supplier France) connected by optical fibers (Thorlabs, USA, supplier France, M25L01) to a cuvette holder (Avantes, the Netherlands, supplier France, CUV-UV/VIS).…”

“…Such methods concern the global “light-culture” interaction rather than the behavior of individual particles. Absorption-based methods like turbidimetry or Beer–Lambert law derived techniques have usually been used and preferred for smaller biological entities such as bacteria but can also be applied to mammalian cells [ 30 ]. These techniques could also be performed in larger volumes [ 3 , 31 , 32 , 33 , 34 ] to determine cell density and viability [ 35 ].…”

“…In this paper, white light spectroscopy was used to measure T-cell concentrations from the shape of the absorption spectra of different dilutions. Indeed, measuring concentrations from the spectral value at only one wavelength (Beer–Lambert derived methods) we proposed [ 30 ] cannot be used to measure concentrations of several species simultaneously. Indeed, the shape of the whole absorption spectrum of a mixture is a combination of the shapes of each individual species.…”