Storage stability and delivery potential of cytochalasin B induced membrane vesicles

Dendritic Cell-Derived Artificial Microvesicles Inhibit RLS40 Lymphosarcoma Growth in Mice via Stimulation of Th1/Th17 Immune Response

Cell-free antitumor vaccines represent a promising approach to immunotherapy of cancer. Here, we compare the antitumor potential of cell-free vaccines based on microvesicles derived from dendritic cells (DCs) with DC- and cationic-liposome-based vaccines using a murine model of drug-resistant lymphosarcoma RLS40 in vivo. The vaccines were the following: microvesicle vaccines—cytochalasin B-induced membrane vesicles (CIMVs) obtained from DCs loaded with total tumor RNA using cholesterol/spermine-containing cationic liposomes L or mannosylated liposomes ML; DC vaccines—murine DCs loaded with total tumor-derived RNA using the same liposomes; and liposomal vaccines—lipoplexes of total tumor-derived RNA with liposomes L or ML. Being non-hepatotoxic, CIMV- and DC-based vaccines administered subcutaneously exhibited comparable potential to stimulate highly efficient antitumor CTLs in vivo, whereas liposomal vaccines were 25% weaker CTL inducers. Nevertheless, the antitumor efficiencies of the different types of the vaccines were similar: sizes of tumor nodes and the number of liver metastases were significantly decreased, regardless of the vaccine type. Notably, the booster vaccination did not improve the overall antitumor efficacy of the vaccines under the study. CIMV- and DC- based vaccines more efficiently than liposome-based ones decreased mitotic activity of tumor cells and induced their apoptosis, stimulated accumulation of neutrophil inflammatory infiltration in tumor tissue, and had a more pronounced immunomodulatory activity toward the spleen and thymus. Administration of CIMV-, DC-, and liposome-based vaccines resulted in activation of Th1/Th17 cells as well as the induction of positive immune checkpoint 4-1BBL and downregulation of suppressive immune checkpoints in a raw PD-1 >>> TIGIT > CTLA4 > TIM3. We demonstrated that cell-free CIMV-based vaccines exhibited superior antitumor and antimetastatic activity in a tumor model in vivo. The obtained results can be considered as the basis for developing novel strategies for oncoimmunotherapy.

Limited T-Cell-Stimulating Effect of Cytochalasin-B-Induced Membrane Vesicles Isolated from Artificial Antigen-Presenting Cells

Artificial antigen-presenting cells (aAPCs) that stably express particular HLA and co-stimulatory molecules by gene transfer have been developed to effectively stimulate T cells. To investigate whether cytochalsin-B-induced membrane vesicles derived from aAPCs (AP-CIMVs) have similar antigen-presenting functions as a cell-free system, T cell responses to different types of antigen presentation were measured using Jurkat reporter cells. First, the aggregation of AP-CIMV, which affects the measurement of function, was inhibited by nuclease treatment to produce uniform AP-CIMVs. The Green fluorescent protein (GFP) expression in Jurkat reporter cells was induced in a dose-dependent manner in groups stimulated with anti-CD3 antibody-coated AP-CIMVs and aAPCs, and anti-CD3/CD28 Dynabead. When Jurkat reporter cells expressing specific T cell receptors were stimulated by AP-CIMVs and aAPCs loaded with CMV pp65 peptide, AP-CIMVs showed similar stimulatory effects to that by aAPC. However, when these Jurkat reporter cells were stimulated by aAPCs endogenously expressing CMV pp65 antigen and their AP-CIMVs, the GFP expression rate by AP-CIMVs was 8.4%, which was significantly lower than 53.2% by aAPCs. Although this study showed a limited T-cell-stimulating effect of AP-CIMVs on endogenously processed antigen presentation, these results provide useful information for the development of improved cell-free systems for T cell stimulation in the future.

Biodistribution of Biomimetic Drug Carriers, Mononuclear Cells, and Extracellular Vesicles, in Nonhuman Primates

Discovery of novel drug delivery systems to the brain remains a key task for successful treatment of neurodegenerative disorders. Herein, the biodistribution of immunocyte-based carriers, peripheral blood mononuclear cells (PBMCs), and monocyte-derived EVs are investigated in adult rhesus macaques using longitudinal PET/MRI imaging. ⁶⁴ Cu-labeled drug carriers are introduced via different routes of administration: intraperitoneal (IP), intravenous (IV), or intrathecal (IT) injection. Whole body PET/MRI (or PET/CT) images are acquired at 1, 24, and 48 h post injection of ⁶⁴ Cu-labeled drug carriers, and standardized uptake values (SUV_mean and SUV_max ) in the main organs are estimated. The brain retention for both types of carriers increases based on route of administration: IP < IV < IT. Importantly, a single IT injection of PBMCs produces higher brain retention compared to IT injection of EVs. In contrast, EVs show superior brain accumulation compared to the cells when administered via IP and IV routes, respectively. Finally, a comprehensive chemistry panel of blood samples demonstrates no cytotoxic effects of either carrier. Overall, living cells and EVs have a great potential to be used for drug delivery to the brain. When identifying the ideal drug carrier, the route of administration could make big differences in CNS drug delivery.