Seeing beyond Labels: Optical Technologies Reshaping Cell Culture Monitoring in Biomedicine

Label-free optical technologies have transformed cell culture monitoring, offering noninvasive alternatives that preserve cellular integrity─a critical factor in biomedical applications such as CAR T therapies and stem cell cultures. This review examines the current landscape of these technologies and their implementation at both laboratory and industrial scales. We highlight key techniques such as quantitative phase imaging, Raman spectroscopy, and autofluorescence imaging, among others, all of which enable multiparameter analysis without exogenous markers. In this direction, recent innovations in instrumentation and data analysis have facilitated the continuous acquisition of morphological and biochemical data from live samples, at both intra- and extracellular levels. These advances are driving the development of more automated, integrated, and unbiased processes that meet the evolving demands of modern cell bioprocesses. This review also emphasizes the collaborative efforts that are shaping label-free technologies in cell culture, bridging multiple disciplines. Additionally, it critically addresses current limitations of the field and explores future directions, particularly for the monitoring of in vitro cells in biomedical applications.