Fig. 2: Transfection efficiency and mechanisms of APOs@BP in MSCs in serum-containing medium.

a Representative fluorescent images of MSCs after FAM-miRNA (green) transfection with ^25KPEI_FAM-miRNA, ^10KPEI_FAM-miRNA, BP_FAM-miRNA, and APOs@BP_FAM-miRNA in medium with or without 10% FBS. b Cell viability after transfection with ^25kPEI_miRNA, ^10kPEI_miRNA, BP_miRNA, and APOs@BP_miRNA in medium with or without 10% FBS. c Cell proliferation in 3 days after transfection with ^25KPEI_miRNA, ^10KPEI_miRNA, BP_miRNA, and APOs@BP_miRNA in medium with 10% FBS. d Representative TEM images of ^25KPEI_miRNA, ^10KPEI_miRNA, BP_miRNA, and APOs@BP_miRNA after incubation in 10% FBS for 2 h. e Evaluation of the stability of ^25KPEI_miRNA, ^10KPEI_miRNA, BP_miRNA, and APOs@BP_miRNA in the presence or absence of serum by measuring particle size, respectively. f Determination of protein adsorption of polymeric complexes by SDS-PAGE. g Schematic illustration of serum-tolerant polymeric complexes to avoid serum-protein adsorption²⁷. h SPR analysis of MSC membrane binding affinity of BSA@BP_miRNA and APOs@BP_miRNA²⁸ i CLSM images of lipid vesicles (labeled with DiI, red) after incubation with FAM labeled BSA@BP_miRNA and APOs@BP_miRNA (green), respectively. The solid white line denotes the straight-line distance employed for colocation analysis between DiI and FAM signals on the right. j The conformational content of APOs in APOs@BP_miRNA before and after incubation with lipid vesicles. k Schematic illustration of intracellular trafficking of APOs@BP_miRNA²⁹. l The dynamic colocalization of APOs@BP_Cy5-miRNA (green) and lysosomes (red) in MSCs after incubation for 0.5 and 2 h, respectively. m Intracellular accumulation and ROS-triggered dissociation of Cy5-miRNA (red) from polymerized carrier (FBP, green). Data were presented as mean ± SD (n = 5 independent samples in b; n = 6 independent samples in c; n = 3 independent samples in e, j;). Two-tailed unpaired t-test was used for statistical analysis of b, j. One-way ANOVA with Dunnett’s multiple comparisons test was used for statistical analysis of c. Three independent experiments were performed with similar results and representative results are shown. Source data are provided as a Source Data file.