Fig. 2: Design of CD38-expressing exosomes and fluorophore-conjugated ARC Exos.

A Schematic representation of designed CD38 fusion proteins for display on exosomal surface via fusing the CD38 extracellular domain to N-terminus of PDGFR TMD (left) or full-length CD38 to C-terminus of CD9 (right). B Immunoblot analysis of purified exosomes. C Enzymatic activity of CD38-expressing exosomes with NGD⁺ substrate. Exosomes (10 µg mL⁻¹) or CD38 protein (20 nM) were incubated with NGD⁺ (100 µM) in PBS. Formation of fluorescent cGDPR product was monitored by fluorescence signals at 410 nm (n = 3 per group). Three biological replications were performed. Data are shown as mean ± SD. D NTA analysis of purified native exosomes and CD9-CD38 Exos (n = 6 per group). Data are presented as mean ± SD. E HPLC analysis of catalytic activity of CD9-CD38 Exos with NAD⁺ substrate. Exosomes (50 μg mL⁻¹) or CD38 protein (200 nM) were incubated with NAD⁺ (200 μM) for 4 h and then analyzed by HPLC. F Synthesis of Alexa 488-ARC Exos. G Visualization of exosomes uptake by HEK293T cells. CD9-CD38 exosomes and native exosomes were incubated without or with 2′-Cl-araNAD⁺-N₃, followed by click reactions with DBCO-Alexa 488. The resulting Alexa 488-ARC Exos along with other exosome controls (50 µg mL⁻¹) were incubated with HEK293T cells for 2 h on ice or at 37 °C, followed by washing, fixation, and confocal microscopic analysis. Scale bars: 20 μm. Experiments in B, G were repeated independently three times with similar results. Source data are provided as a Source Data file.