Exosomes in Dogs and Cats: An Innovative Approach to Neoplastic and Non-Neoplastic Diseases

Abstract

Exosomes are extracellular vesicles with a diameter between 40 and 120 nm, which are derived from all types of cells and released into all biological fluids, such as blood plasma, serum, urine, breast milk, colostrum, and more. They contain proteins, nucleic acids (mRNA, miRNA, other non-coding RNA, and DNA), and lipids. Exosomes represent a potentially accurate footprint of the miRNA profile of the parental cell and can therefore be proposed as potential and sensitive biomarkers, both in diagnosing and monitoring a variety of diseases in humans and animals. Liquid biopsy offers itself as a non-invasive or minimally invasive, pain-free, time-saving alternative to conventional tissue biopsy. Exosomes in both human and veterinary medicine find their major application in neoplastic diseases, but applications in the field of veterinary cardiology, nephrology, reproduction, parasitology, and regenerative medicine are currently being explored. Exosomes can therefore be used as diagnostic, prognostic, and, in some cases, therapeutic tools for several conditions. The aim of this review was to assess the current applications of exosomes in veterinary medicine, particularly in dog and cat patients.

Keywords: biomarkers; cat; dog; exosomes; extracellular vesicles; miRNA; veterinary medicine.

Figure 1

Exosome cross-talking. The biogenesis of exosomes begins with endocytosis to form early endosomes by inward budding, then form late endosomes, and ultimately produce multivesicular bodies (MVBs). MVBs merge with the cell membrane and, by exocytosis, release exosomes into the extracellular environment [1]. Exosomes modulate the recipient cell’s gene expression by initiating cell signaling as well as intercellular transfer of the protein, lipid, and RNA cargo, not only in a functional setting (blue exosomes in the picture) but also in cancer (gray exosomes), infectious (red exosomes), and parasitic (yellow exosomes) diseases, gaining clinical significance because of their potential use as biomarkers or next-generation therapeutics [11]. Abbreviations in the picture: MVB, multivesicular bodies; HSP, heat shock protein; ALIX, ALG-2-interacting protein X; TSG101, tumor susceptibility gene 101; CD, cluster of differentiation.