![]() ![]() Lasers are the excitation light sources for virtually every modern flow cytometer. Here we review the modern methods and approaches used for flow cytometer design, cell labeling, their viability evaluation, and cell sorting along with other methods to separate cell subpopulations and the automatic approaches for following data analysis based on machine learning and deep learning methods. Currently, there are a number of methods based on the physical and biological properties of cells, allowing their sorting. Development of new fluorophores and methods of labeling different cell structures allowed for sorting cells according to many features and selection of small subpopulations and even single cells. The significant step towards the isolation of rare blood circulating objects was the invention of the Fluorescence Activated Cell Sorter (FACS) by Bonner, Sweet, Hulett, Herzenberg et al. However, the negative approach is more efficient for untypical object analysis in lymph or blood due to the exclusion of all objects except for embolus. Both of these methods have advantages and disadvantages. Oppositely, the negative selection means the exclusion of all objects except for the target. The positive selection implicates the direct isolation of target objects from a general population. Generally, there are two opposite approaches for the selection of target cell subpopulations from the entire population. Theoretically, other emboli types such as a fat embolism and blood clots can be found by the analysis of a blood sample as well. Bloodstream infections also can be diagnosed by the detection of microorganisms in the blood. brucei ) and cause infectious diseases like babesiosis, Chagas disease, malaria, African trypanosomiasis, etc. divergens, Trypanosoma cruzi, Plasmodium falciparum, P. Some species of Protozoa that parasitize in human (e.g., Babesia microti, B. For example, CTCs are the prognostic factor of different cancer types, which can be detected at early stages. A number of diseases could be diagnosed by detecting of untypical blood objects-emboli in the lymph or blood. However, there is no doubt that a solution to the current main medical issues is related to the detailed analysis of single cells, which requires their separation from ordinary objects.Ĭurrently, liquid biopsy is one of the most informative and broadly described analyses in medicine. For example, the object size is limited by the resolution of the cytometer optical system, and there are flow speed limits based on the sensitivity of detection scheme, laminarity of object flow and required quality of the image. The last generation of the flow cytometry systems with the possibility of object visualization allows verifying received data but has additional restrictions. However, there are two significant challenges: the first one is the rarity of untypical blood elements and the second one is the small volume of the sample that has to be subjected to detailed analysis. The promising approach to diagnose these diseases is the detection of untypical objects in blood and lymph samples. During 2016, 216 million cases of malaria were detected. Here we provide an overview of different techniques designed to detect very rare objects in the blood flow, sort it out or filter from the bloodstream and extract for further investigation.Īccording to the statistics of the World Health Organization for 2016, around 71% of the overall 57 million deaths are caused by noncommunicable diseases, including cardiovascular disease-31% and cancer-16%. The current state of the art in this field is defined by the progress in cell imaging and sorting techniques, sample enrichment, and separation along with the new approaches for automatization of data analysis based on machine learning and deep learning methods. In addition to the detection and extraction of such rare objects, a lot of developments are targeted on eliminating it from the blood flow by a sort of blood filtering. This includes the search for the very rare circulating tumor cells (CTCs) at early stages of cancer development by liquid biopsy, the detection of microorganisms during acute blood infections to determine its strain very rapidly, early detection of malaria parasites including in vivo and other pathogenic states that impose high risks to human life and well-being. The problem of detection and extraction of rare objects from the blood flow arises in a number of situations. ![]()
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