Heterologous and cross-species tropism of cancer-derived extracellular vesicles

Abstract

Extracellular vesicles (EVs) are naturally occurring cargo delivery vesicles that have recently received considerable attention for their roles in intercellular communication in many physiological and pathological processes, including tumourigenesis. EVs generated by different tissues demonstrated specific homing: in particular, cancer-derived EVs showed a selective tropism for the tumor tissue from which the vesicles originated. For this property, EVs have been proposed as drug delivery tools for anti-cancer therapies, although the limited knowledge about their in vivo tropism hinders their therapeutic applications. The current study aimed to characterize the targeting properties of cancer-derived EVs in vitro and their biodistribution in vivo, by using an imaging approach.Methods: EVs were generated from: i) murine lung (LL/2) and colon (MC-38) cancer lines, ii) human lung cancer cell line (A549) and iii) human liver biopsy samples from healthy individuals. EVs were loaded with fluorescent dyes alone or in combination with a biopharmaceutical agent, the oncolytic adenovirus (OV), characterized for charge and size and tested for their activity in cancer cell lines. Finally, optical imaging was extensively applied to study in vivo and ex vivo the biodistribution of EVs originated from different sources in different mouse models of cancer, including xenograft, syngeneic graft and the MMTV-NeuT genetically modified animal.Results: We initially demonstrated that even loading EVs even with a large biopharmaceutical oncolytic viruses (OVs) did not significantly change their charge and dimension properties, while increasing their anti-neoplastic activity compared to the virus or EVs alone. Interestingly, this activity was observed even if the EVs derived from lung cancer were applied to colon carcinoma cell lines and vice versa, suggesting that the EV uptake occurred in vitro without any specificity for the cancer cells from which the vesicles originated. When administered i.v (intravenously) to the mouse models of cancer, the tumour-derived EVs, but not the EVs derived from a healthy tissue, demonstrated a selective accumulation of the fluorescence at the tumour site 24 h after injection; adding OVs to the formulation did not change the tumour-specific tropism of the EVs also in vivo. Most interestingly, the in vivo experiments confirmed the in vitro observation of the generalized tropism of tumour-derived EVs for any neoplastic tissue, independent of the tumour type or even the species originating the vesicles.Conclusions: Taken together, our in vitro and in vivo data demonstrate for the first time a heterologous, cross-species tumour-tropism for cancer-derived EVs. This finding challenges our current view on the homing properties of EVs and opens new avenues for the selective delivery of diagnostic/therapeutic agents to solid tumours.

Advances in Analysis of Biodistribution of Exosomes by Molecular Imaging

“…The tumor-homing of MSC-exosomes has been successfully adopted to deliver therapeutic miRNAs to reduce tumors in xenograft mice with patient-derived pancreatic cancer [45], and syngeneic breast tumors in mice [90]. Interestingly, beyond organotropism of tumor exosomes, generalized tropism of tumor exosomes toward neoplastic tissues from different types or species have also been reported [106].…”

Therapeutic Advances of Stem Cell-Derived Extracellular Vesicles in Regenerative Medicine

“…EVs can be utilized as vectors to deliver oncolytic viruses to tumor sites [107]. Oncolytic viruses are promising in the treatment of various cancers because they selectively infect cancer cells, synchronously stimulate the immune response and attract more immune cells to continue to kill residual cancer cells [108][109][110]. However, delivery of oncolytic viruses to tumor sites remains a major challenge.…”

“…However, delivery of oncolytic viruses to tumor sites remains a major challenge. Garofalo et al demonstrated that oncolytic viruses could be delivered by tumor-derived EVs (T-EVs), which increases their antitumor properties and displays a selective tropism for any tumor sites, independent of the tumor type originating the EVs [110]. They further found that tumor tropism is achieved when oncolytic viruses are loaded inside T-EVs that are injected intravenously, but not when administrated intraperitoneally [111].…”

How Computational Chemistry and Drug Delivery Techniques Can Support the Development of New Anticancer Drugs

“…In the last decades, extracellular vesicles (EVs) have been found to exert different biological functions in both physiological and pathological conditions explaining the rapid growth of interest in this research field. EVs are nano-to micron-sized lipid membrane-bound vesicles secreted into the extracellular environment transporting proteins, lipids and nucleic acids from cell to cell [127]. They are naturally occurring cargo delivery agents with the potential to be used as vehicles for drug delivery [128,129].…”

“…Furthermore, bioluminescence and fluorescence imaging technologies indicate a selective delivery of EVs to the tumor tissue allowing to insulate the delivered agents, thus potentially preventing undesired off-target effects of the transported drugs due to their systemic delivery [147]. Interestingly, another advantage of using EVs is their heterologous and cross-species cancer specific homing capabilities that could open new avenues for the selective delivery of diagnostic/therapeutic agents to different tumor types [127]. The possible existence of a selective ligand-receptor mechanism responsible for the EV-tumor tropism paves the way for future research aimed at developing biocompatible nanovesicles with a cancer-selective homing which is instrumental for future clinical applications where the delivery of diagnostic agents may be combined with the loading of drugs or radiotherapeutic isotopes for curing tumor micrometastasis and residual neoplastic cells eventually remaining in the normal tissue after conventional cancer treatments [148].…”