Needle-Free Injection Enhances the Immunogenicity and Antitumor Efficacy of Whole-Cell Tumor Vaccines

Background/Objectives: Whole-cell vaccines have demonstrated clinical potential in cancer treatment and recurrence prevention, yet their immunogenicity and dendritic cell (DC) activation remain suboptimal. This study aimed to evaluate whether a needle-free injector (NFI) could enhance the immunogenicity and antitumor efficacy of whole-cell tumor vaccines. Methods: Adaptive immune responses induced by NFI and traditional syringe injection (SYI) were compared following whole-cell vaccine administration. The morphology of vaccine fluid ejected by NFI and SYI was examined, and the effects on DC antigen uptake and activation were assessed. Antitumor efficacy was further evaluated in MC38 colon adenocarcinoma challenge models. Results: NFI administration elicited stronger antigen-specific adaptive immune responses than SYI. The high-velocity pressure generated by NFI resulted in fragmentation of whole-cell vaccine material, and this morphological alteration was associated with enhanced DC antigen uptake and activation. These immunological improvements corresponded with superior tumor suppression in MC38 models following NFI-delivered vaccination. Conclusions: NFI delivery enhances the immunogenicity and antitumor efficacy of whole-cell tumor vaccines. These findings suggest that needle-free injectors may serve as a simple and effective strategy to improve the performance of whole-cell cancer vaccines.