Single-cell oxygen saturation imaging characterizes RBC O2-handling kinetics. (A) Microfluidic chamber for producing rapid solution exchange in imaged RBCs under superfusion. (B) Rapid exchange is achieved in the millisecond scale (frame acquisition: 51 ms). (C) Experiment on freshly drawn venous blood showing time course of oxygen unloading from imaged RBCs, quantified in terms of time constant (τ) and capacity (κ). (D) Reference blood freshly drawn from veins of healthy volunteers. Distribution by blood group, donor age, mean corpuscular volume (MCV), and mean corpuscular Hb concentration (MCHC). On each box, the central mark indicates the median; bottom and top edges indicate the 25th over 75th percentiles; the whiskers extend to the most extreme data points not considered outliers. (E) Analysis of reference blood. (Top) Time constant frequency distribution (red curve shows mean) and summary statistics; (bottom) capacity frequency distribution and summary statistics. (F) Stored blood used for perfusions. Distribution by blood group and distribution of storage time (days). (G) Analysis of stored blood. (Top) Time constant frequency distribution (green line shows reference blood mean) and summary statistics; (bottom) capacity frequency distribution and statistics. (H) Analysis of venous blood obtained from recipient of the kidney. (Top) Time constant statistics; (bottom) capacity statistics.
