In vivo biodistribution of PKH26-labeled huMkMPs administered to untreated WT mice and huMkMP colocalization with murine blood cells. Murine tissues were excised, homogenized, and analyzed for fluorescence (SpectraMax i3x) 4 and 24 hours after administration of huMkMPs and CHO-MVs. (A) Experimental schema for measuring tissue-specific fluorescence. (B) MFI in each excised tissue relative to total fluorescence in all tissues (n = 6 mice per MkMP group; n = 3 mice in CHO-MV group). (C) MFI of each tissue normalized by tissue weight is shown. (D) PKH26-labeled huMkMPs (6 × 10⁶), or saline control were administered to BALB/c mice. Tissues, including BM, lung, liver, and spleen, were collected after 4 hours for single-cell isolation. Harvested cells were stained with anti-CD41 antibody and analyzed via flow cytometry (n = 2). (E) Single cells isolated from the liver were analyzed by flow cytometry for colocalization of PKH26 signal with CD41, CD117, or CD45 signals (n = 2). Error bars represent the SEM. The unpaired 2-tailed Student t test was used to determine statistical significance. *P < .05. Higher P values of some comparisons are displayed over the bars.