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Cancer vaccines have been extensively studied in recent years and have contributed to exceptional achievements in cancer treatment. They are some of the most newly developed vaccines, although only two are currently approved for use, Provenge and Talimogene laherparepvec (T-VEC). Despite the approval of these two vaccines, most vaccines have been terminated at the clinical trial stage, which indicates that although they are effective in theory, concerns still exist, including low antigenicity of targeting antigens and tumor heterogeneity. In recent years, with new understanding of the biological function and vaccine potential of outer membrane vesicles (OMVs), their potential application in cancer vaccine design deserves our attention. Therefore, this review focuses on the mechanisms, advantages, and prospects of OMVs as antigen-carrier vaccines in cancer vaccine development. We believe that OMV-based vaccines present a safe and effective cancer therapeutic option with broad application prospects.

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As the trend of antibiotic resistance has increased, prevention and treatment of Helicobacter pylori infection have been challenged by the fact that no vaccines preventing H. pylori infection are available. Scientists continue to make sustained efforts to find better vaccine formulations and adjuvants to eradicate this chronic infection. In this study, we systemically analyzed the protein composition and potential vaccine function of outer-membrane vesicles (OMVs) derived from gerbil-adapted H. pylori strain 7.13. In total, we identified 169 proteins in H. pylori OMVs and found that outer-membrane, periplasmic and extracellular proteins (48.9% of the total proteins) were enriched. Furthermore, we evaluated the immune protective response of H. pylori OMVs in a C57BL/6 mouse model, and mice were orally immunized with OMVs or the H. pylori whole cell vaccine (WCV) alone, with or without cholera toxin (CT) as an adjuvant. The data demonstrated that oral immunization with OMVs can elicit a strong humoral and significantly higher mucosal immune response than the group immunized with the WCV plus the CT adjuvant. Moreover, our results also confirmed that OMVs predominantly induced T helper 2 (Th2)-biased immune responses that can significantly reduce bacterial loads after challenging with the H. pylori Sydney Strain 1 (SS1). In summary, OMVs as new antigen candidates in vaccine design would be of great value in controlling H. pylori infection.

The combined use of peptides, nanomaterials, and hydrogels is a promising strategy for chronic skin wound healing, which remains a huge clinical challenge. Here, we optimized the RL-QN15 peptide, which was shown to be a pro-healing drug candidate in our previous research, to obtain the cyclic heptapeptide (CyRL-QN15) with considerable therapeutic potency against skin wounds. Furthermore, a Zn2+-crosslinked sodium alginate (ZA) hydrogel containing hollow polydopamine (HPDA) nanoparticles loaded with CyRL-QN15 (HPDAlCyRL-QN15/ZA hydrogel) was prepared and characterized, which significantly enhanced the pro-healing potency of CyRL-QN15. At the cellular level, this nontoxic hydrogel accelerated the proliferation, migration, tube formation, and scratch healing of skin cells, regulated the secretion of cytokines from macrophages, directly scavenged free radicals, and decreased reactive oxygen species. Moreover, the HPDAlCyRL-QN15/ZA hydrogel significantly accelerated the healing of full-thickness skin wounds in type 2 diabetic mice by promoting the transition of macrophages to the M2 phenotype to reduce inflammation and cause re-epithelialization, formation of granulation tissue, deposition of collagen, and angiogenesis. Of note, the hydrogel also facilitated wound healing of diabetic patient skin cultured ex vivo. Overall, the HPDAlCyRL-QN15/ZA hydrogel presents a novel therapeutic strategy for clinical chronic skin wound (diabetic ulcer) healing.