Fig. 6: Comparison of the in vivo fate of IPM and LNP.

a Fluorescence imaging of healthy male C57BL/6 mice (6–8 weeks old) injected with FAPi-IPM, IPM, or LNP/FAM-siNC via the tail vein at 2, 4, 8, and 24 h. LNP enters the liver more rapidly and is rapidly cleared, while FAPi-IPM exhibits prolonged liver distribution. b Immunofluorescence staining of liver tissue (F4/80 labeling KCs) at 24 h post-injection reveals differences in uptake among formulations. c ROI values indicate LNP accumulates most in the liver at 4 h, whereas FAPi-IPM shows delayed liver accumulation at 24 h (n = 3 mice). d Pearson’s R of FAM fluorescence and KCs in liver showing rapid phagocytosis of LNP by KCs at 2–4 h (n = 3 mice). e Cell distribution changes show LNP is captured by hepatocytes and Kupffer cells at 2 h, while FAPi-IPM enters hepatocytes later at 8 h; IPM enters hepatocytes less overall (n = 3 mice). f In the spleen, all formulations are mainly taken up by mononuclear cells, with FAPi-IPM showing the highest uptake (n = 3 mice). g The 2-h FAM colocalization results in the spleen indicate that all three formulations strongly colocalize with neutrophils and are mostly taken up by neutrophils. h Schematic representation of dosing regimen: PEGylated drug injections on days 0, 3, 6, and 9, with pharmacokinetic assays on days 1 and 10, and anti-PEG IgM levels assessed on days 1, 3, 6, 9, and 14 (n = 6 mice). i Pharmacokinetic curves of the three PEGylated drugs and pharmacokinetic curves rechallenged on day 10. AUC_0-24 of the three PEGylated drug on day 1 (j) and day 10 (k). l Ratio of AUC_0-24 rechallenged and AUC_0-24. Data were analyzed using ANOVA, with Sidak multiple comparisons for Fig. 6c, and Tukey multiple comparisons for others. Values represent mean ± standard deviation (SD).