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Graner. Extracell Vesicles Circ Nucleic Acids 2020;1:3-19 I http://dx.doi.org/10.20517/evcna.2020.08 Page 11

which has different features from growth factor-driven angiogenesis, may help explain the failure of anti-
VEGFA targeting across several clinical trials in GBM.

The theme of detrimental impacts of disease-state EVs on normal cells was continued by Romano Regazzi
(University of Lausanne, Switzerland). In the context of Type 1 diabetes, modeled in NOD mice, his group
showed that certain microRNA levels (miRs-142-3p; -142-5p; -150; -155) are elevated in pancreatic beta
cell islets, and in sorted beta cells, in the pre-diabetic state, and this is not in response to proinflammatory
cytokines. However, these miR levels are increased in the infiltrating lymphocytes, begging the question
that miRs may be transferred from leukocytes to beta cells. Jurkat cells (model CD4+ T cells) released EVs
containing relatively high amounts of miRs-142-3p, -142-5p, and -155, which were indeed transferred to
cultured beta cells upon incubation with the T cell EVs. These beta cells increased gene expression levels of
several other chemokines in response to T cell EVs, and transfection of the beta cells with the miR mimics
promoted the same expression changes. EV exposure also drove apoptotic beta cell death (without affecting
other pancreatic cell types), and this was also mimicked by individual miR transfections into beta cells.
While non-beta cells also take up lymphocyte EVs, only beta cells exhibited gene expression changes; of note,
NF-kB nuclear translocation also occurred in the beta cells, suggesting a global driver of the cyto/chemokine
expression changes. Gratifyingly, these effects were replicated in human tissues as well. Transfection of beta
cells with anti-miRs apparently successfully prevented the impact of lymphocyte EV-transferred miRs, as this
halted the apoptotic effect of the EVs. For an in vivo therapeutic attempt, the research group generated a “miR
sponge” construct used in beta cell-targeted AAV transfection; this reduced the number of mice progressing
with the disease. Continuing work will examine the roles of other non-coding RNAs that may be transferred
from lymphocytes to beta cells.

Dennis Steindler (University of North Carolina; University of Florida, US) followed with more examples
of exosome/microvesicle (EMV)-driven pathologies. He introduced the concept of adult neural stem cell-
driven disease as a proliferative failure (e.g., Alzheimer’s and Parkinson’s disease) or a proliferative excess
(e.g., brain tumors). Focusing on Parkinson’s disease, his group has identified human adult neural progenitor
(AHNP) cells that are capable of proliferation and differentiate into neurons and glia. The cells are from cases
of both idiopathic Parkinson’s and gene-identified Parkinson’s. These cells release EMVs that bear signature
profiles in nanoparticle tracking analysis; in the case of gene-identified Parkinson’s, correction of the
mutation returns the mutant EMV profile towards normal cell EMV profiles. This holds true for content of
EMVs as well. There are interesting overlaps in neurodegenerative diseases between transmission of disease
states from cell to cell with near infectious (viral-like) aspects. One hypothesis is that the neural connectome,
perhaps via the vagus nerve, is hijacked to put such particles, including EMVs, into the central nervous
system.

Moran Amit (MD Anderson Cancer Center, US) further connected the pathologic conditions (e.g., head
and neck cancer) that alter normal cell function (neural reprogramming) via exosomes. Until recently,
oncologists have viewed nerves involved in cancer as innocent bystanders. We now know that cancer cells
can migrate or metastasize along neural tracks, and possibly have a more active role in tumor progression
and malignancy. Tumor innervation is often associated with worse outcomes, but little is known about this.
Using an in vitro ganglion + tumor cell assay, some tumor cells could promote neuritogenesis better than
others; a common feature among those cells was the loss of p53, and this held true in murine studies, even
in a pre-malignant stage prior to cancer cell/neuron contact. Thus, there should be a secreted component,
which appears to be p53-deficient/mutant exosomes. miR-34a, present in p53wt exosomes, restricts
neuron growth. In p53 mutant exosomes, in the absence of miR-34a, miR-21 and -324 strongly promote
neuritogenesis. Phenotypically, the neurons are mostly sympathetic, have dysregulated pathways in stemness,
proliferation, and neural transmission, and may even switch phenotypes. Beta-blockers may inhibit this
neuronal-promoted tumor growth.