Erythrocyte lysis and angle-resolved light scattering measured by scanning flow cytometry result to 48 indices quantifying a gas exchange function of the human organism

Cell or cell derivative-laden hydrogels for myocardial infarction therapy: from the perspective of cell types

Myocardial infarction (MI) is a global cardiovascular disease with high mortality and morbidity. To treat acute MI, various therapeutic approaches have been developed, including cells, extracellular vesicles, and biomimetic nanoparticles. However, the clinical application of these therapies is limited due to low cell viability, inadequate targetability, and rapid elimination from cardiac sites. Injectable hydrogels, with their three-dimensional porous structure, can maintain the biomechanical stabilization of hearts and the transplantation activity of cells. However, they cannot regenerate cardiomyocytes or repair broken hearts. A better understanding of the collaborative relationship between hydrogel delivery systems and cell or cell-inspired therapy will facilitate advancing innovative therapeutic strategies against MI. Following that, from the perspective of cell types, MI progression and recent studies on using hydrogel to deliver cell or cell-derived preparations for MI treatment are discussed. Finally, current challenges and future prospects of cell or cell derivative-laden hydrogels for MI therapy are proposed.

4π light scattering flow cytometry: enhancing the identification and characterization of individual cells

The analysis of individual particles with complex morphologies from light scattering is crucial in disperse systems studies, such as blood cells. Characterization, which assumes determining particle characteristics, has a higher likelihood of succeeding in solving the inverse light-scattering problem if an instrument provides enough light-scattering data. In this study, we demonstrate how we extend the operating angular interval for the 4π Scanning Flow Cytometer (4πSFC), which measures angle-resolved light-scattering profiles (LSPs) of individual particles. The angular interval is extended by additionally measuring light scattering for the backward hemisphere. Currently, the 4πSFC setup uses three lasers, a single optical cell, and three photomultipliers. It enables the measurement of the LSP of individual particles within the angular interval of 10 to 170° for polar angles with integration over azimuth angles, which covers the spatial angle of 98.5% of the 4π angle. We demonstrate the 4πSFC's performance in measuring LSPs from the analysis of polymer beads, mature and spherized erythrocytes, and platelets. The 4πSFC has the potential to be very useful in identifying platelet dimers and granulocytes without labels, characterizing lymphocytes, monocytes, and abnormal erythrocytes.

A light scatter based model relating erythrocyte vesiculation to lifetime in circulation

Methods for measuring erythrocyte age distribution are not available as a simple analytical tool. Most of them utilize the fluorescence or radioactive isotopes labeling to construct the age distribution and support physicians with aging indices of donor's erythrocytes. The age distribution of erythrocyte may be a useful snapshot of patient state over 120-days period of life. Previously, we introduced the enhanced assay of erythrocytes with measurement of 48 indices in four categories: concentration/content, morphology, aging and function (10.1002/cyto.a.24554). The aging category was formed by the indices based on the evaluation of the derived age of individual cells. The derived age does not exactly mean the real age of erythrocytes and its evaluation utilizes changes of cellular morphology during a lifespan. In this study, we are introducing the improved methodological approach that allows us to retrieve the derived age of individual erythrocytes, to construct the aging distribution, and to reform the aging category consisting of eight indices. The approach is based on the analysis of the erythrocyte vesiculation. The erythrocyte morphology is analyzed by scanning flow cytometry that measures the primary characteristics (diameter, thickness, and waist) of individual cells. The surface area (S) and sphericity index (SI) are calculated from the primary characteristics and the scattering diagram SI versus S is used in the evaluation of the derived age of each erythrocyte in a sample. We developed the algorithm to evaluate the derived age that provides eight indices in the aging category based on a model using light scatter features. The novel erythrocyte indices were measured for simulated cells and blood samples of 50 donors. We determined the first-ever reference intervals for these indices.

Ultraviolet light scattering scanning flow cytometry in the characterization of submicron microparticles

Ultraviolet lasers are commonly used in flow cytometry to excite fluorochrome molecules with subsequent measurement of the specific fluorescence of individual cells. In this study, the performance of the ultraviolet light scattering (UVLS) in the analysis of individual particles with flow cytometry has been demonstrated for the first time. The main advantage of the UVLS relates to the improvement of the analysis of submicron particles due to the strong dependence of the scattering efficiency on the wavelength of the incident light. In this work, submicron particles were analyzed using a scanning flow cytometer (SFC) that allows measurements of light scattering in an angle-resolved regime. The measured light-scattering profiles of individual particles were utilized in solution of the inverse light-scattering problem to retrieve the particle characteristics using a global optimization. The standard polystyrene microspheres were successfully characterized from the analysis of UVLS which provided the size and refractive index (RI) of individual beads. We believe that the main application of UVLS relates to the analysis of microparticles in a serum, in particular in the analysis of chylomicrons (CMs). We have demonstrated the performance of the UVLS SFC in the analysis of CMs of a donor. The RI versus size scatterplot of CMs was successfully retrieved from the analysis. The current set-up of the SFC has allowed us to characterize individual CMs starting from the size of 160 nm that provides determination of the CM concentration in a serum with flow cytometry. This feature of the UVLS should help with the analysis of lipid metabolism measuring RI and size map evolution after lipase action.