The potential of antigen and TriMix sonoporation using mRNA-loaded microbubbles for ultrasound-triggered cancer immunotherapy

Abstract

Dendritic cell (DC)-based cancer vaccines, where the patient's own immune system is harnessed to target and destroy tumor tissue, has emerged as a potent therapeutic strategy. In the development of such DC vaccines, it is crucial to load the DCs with tumor antigens, and to simultaneously activate them to become more potent antigen-presenting cells. For this, we report on microbubbles, loaded with both antigen mRNA as well as immunomodulating TriMix mRNA, which can be used for the ultrasound-triggered transfection of DCs. In vivo experiments with in vitro sonoporated DCs, show the effective induction of antigen-specific T cells, resulting in specific lysis of antigen-expressing cells. Especially in a therapeutic setting, sonoporation with TriMix has a significant added value, resulting in a significant reduction of tumor outgrowth and a marked increase in overall survival. What is more, complete tumor regression was observed in 30% of the antigen+TriMix DC vaccinated animals, which also displayed long-term antigen-specific immunological memory. As a result, DC sonoporation using microbubbles loaded with a combination of antigen and TriMix mRNA can elicit powerful immune responses in vivo, and might serve as a potential tool for further in vivo DC vaccination applications.

Evading innate immunity in nonviral mRNA delivery: don’t shoot the messenger

“…Nevertheless, studies in the field of cancer immunotherapy have demonstrated that neither sono-nor electroporation results in strong activation of immune cells. In fact, both techniques require additional stimulation with adjuvants to induce therapeutically beneficial immune responses [79,80]. This might indicate that cytosolic PRRs are less immunogenic than endosomal TLRs.…”

Ultrasound-mediated microbubble destruction: a new method in cancer immunotherapy

“…It has been demonstrated that transfection is significantly enhanced using microtubules, and US can activate powerful immune responses in vivo, which can be applied as a potential method for further clinical trials (Figure 3). 50 Oda et al used microbubbles combined with US irradiation to deliver antigens that were extracted from tumor cells into DCs and then investigated the therapeutic effect of the treated DCs on a mouse model of lung metastasis. The results demonstrated that prophylactic immunization with this strategy showed significant suppression (a four-fold decrease) of melanoma lung metastases 51…”

In vitro methods to study bubble-cell interactions: Fundamentals and therapeutic applications

“…Cancer cells are easy to culture and to manipulate and therefore useful for fundamental studies. Finally, dendritic cells 14 or lymphocytes 22 are also interesting targets, e.g., for immunotherapy, since these can be reached directly from the blood stream or from the lymphatic nodes after subcutaneous injection and drainage of the microbubbles.…”