Establishment of proprotein convertase subtilisin/kexin type 9 nanovaccine and in vitro study on cellular uptake efficiency

Objective To prepare proprotein convertase subtilisin/kexin type 9 (PCSK9) nanovaccine and preliminarily discuss its in vitro uptake efficiency by dendritic cells (DC 2.4). Methods PCSK9207-223was selected as antigen peptide, with bovine serum albumin (BSA) as carrier pro-tein, so as to transform BSA molecules into BSA nanoparticles (BNs) by the "reduction-heating-oxidation" method. PCSK9 peptide was linked to the sur-face of BNs to synthesize BSA-PCSK9 nanoparticles (BPNs). PCSK9 peptide was directly linked with BSA molecules to synthesize molecular vaccine BSA-PCSK 9 (BP). The particle size and potential of BNs and BPNs were determined by dynamic light scattering and the morphology was observed un-der a transmission electron microscope. Antigen loading was analyzed by sodium dodecyl sulfate-poyacrylamide gel electrophoresis (SDS-PAGE). The particle size changes of BPNs at different time points were measured to assess its stability under the physiological environment. BPNs were incubated with DC 2.4 for 24 h, and DC 2.4 viability was tested by enhanced cell counting kit-8 (CCK8) to reflect BPN biocompatibility. The uptake of DC 2.4 to-wards nanovaccine was assessed by flow cytometry. Results The synthesized BPNs had a particle size of (68.2±3.1) nm and a potential of(−14.8± 0.6) mV, with an almost spherical shape under a transmission electron microscope. SDS-PAGE results showed an increase in the relative molecular weight of BPNs, which suggested the successful linkage of the short peptide. The particle size of BPNs remained stable under the mimic physiological en-vironment over 144 h. Enhanced CCK8 results indicated that the viability of DC 2.4 was over 100%. According to flow cytometry, DC 2.4 exhibited high-er uptake efficiency towards BPNs than BPs. Conclusions BPNs have good in vitro stability and biocompatibility and are easily to be uptaken by DC. Key words: Proprotein convertase subtilisin/kexin type 9; Nanovaccine; Dendritic cell; Phagocytosis