Flow Cytometry: Historical Perspectives, Fundamentals, Past and Present Instrumentations, and Applications

The development of the microscope widened up novel possibilities for recognizing the existence of cells across various organisms. The advancements in microscopy technology, ranging from bright field to electron microscopy, enhance our comprehension of cellular structures and functions at the molecular level. The examination of cells, known as cytology, focusses on cellular characteristics and the assessment of the physical and/or chemical attributes of individual cells through the use of microscopy, a process termed “cytometry.” A technology introduced around five decades ago, called “flow cytometry,” has revolutionized the study of cells. It complements microscopy by enabling the rapid measurement of cellular properties as cells flow through a stream. Since its invention, flow cytometry has undergone considerable evolution and has emerged as a crucial technique with extensive applications in various fields, as it facilitates the simultaneous analysis of multiple characteristics of individual cells in a high-throughput manner. Further advancements in flow cytometry have resulted in the emergence of sophisticated technologies including image enabled fluorescent activated cell sorting, imaging flow cytometry, mass cytometry, and full spectrum flow cytometry. Moreover, the decrease in lab space has led to the creation of compact bench-top analysers, enhancing the accessibility of flow cytometry across various research and clinical environments. Furthermore, the utilization of artificial intelligence and machine learning boosts data clarity, enhances signal identification, and streamlines the examination of intricate data. This chapter provides a comprehensive examination of the historical evolution of flow cytometry, covering essential principles, technological advancements, scientific and clinical uses, as well as the constraints of both past and current flow cytometers.