What are Exosomes?

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What are exosomes? For many years, exosomes were considered to be transporters of cellular waste, but they are now recognized for their essential role in intercellular communication and transportation.

what are exosomes | definition

In this article:

  • Definition of Exosomes
  • Exosome Size
  • Exosome Sources
  • Exosome Characteristics
  • Exosome Review
  • Exosome Research
  • Cancer Exosomes
  • Exosome Therapeutics
  • First EV Therapeutic Entering Human Trial
  • Exosome Market
  • Exosome Global Strategic Report

Definition of Exosomes

Exosomes are defined as small vesicles ranging from 30-100nm in size that are found in nearly all eukaryotic fluids and facilitate a range of important cellular functions. They transfer DNA, RNA, and proteins to other cells, thereby altering the function of the target cells.

Exosome Size

The diameter of exosomes can range from 30 nm on the low end to 100 nm on the high end. Because exosomes have a low refractive index and are less than 100 nm in diameter, the separation of exosomes from similar sized cells and vesicles can be a challenge.

For this reason, the isolation of pure populations of exosomes may involve physical techniques based on size and density, as well as techniques that utilize biochemical parameters.

What are Exosomes? | Exosome Definition

Exosome Sources

Exosomes are present in nearly all body fluids, including:

  • Blood
  • Urine
  • Saliva
  • Synovial fluid
  • Amniotic fluid
  • Semen
  • Vaginal fluid
  • Breast milk
  • Serum and plasma from cancer patients
  • Cultured medium of cell cultures
  • And more

Exosome Characteristics

Exosomes are characterized by the following features:

  • Range from 30-100nm in size
  • Found in nearly all bodily fluids
  • Exported by all eukaryotic cell types
  • Exosome properties reflect the donor cell
  • Produced in extremely abundant amounts

Exosome Review

A review of exosome activity reveals that there has been an explosion in scientific research in recent years. For decades, exosomes were considered extracellular byproducts, but these nano-sized vesicles are now becoming increasingly recognized for their critical role in intercellular communication for both healthy and diseased cell types.

Exosomes have an extraordinary ability to transfer proteins, DNA, mRNA, non-coding RNAs.

Substantial research suggests that understanding the role of cancer exosomes will be critical to the future of human health because exosomes have the potential to be used in cancer prevention, diagnosis, and therapeutic care.

Exosome Research

Exosome research is being rapidly explored within academic research settings and private industry. When exosome publications are analyzed, U.S. authors have published approximately 40% of the articles and China takes second place.

However, when the term “exosome” is searched in the scientific literature, Dr. Susanne Gabrielsson from the Karolinska Institutet in Sweden is the leading author with 37 articles.

When the term “extracellular vesicles” is searched, Unicyte AG, a regenerative medicine unit of Fresenius Medical Care, takes the lead. The company has published 100+ papers on exosomes and extracellular vesicles in collaboration with Professor Giovanni Camussi.

Most recently on July 30, 2018, Fresenius Medical Care announced that Unicyte AG achieved a key preclinical milestone in its regenerative medicine program for chronic kidney disease. The company confirmed the “disease-modifying potential for its proprietary nano-Extracellular Vesicles…in a second preclinical model of chronic kidney disease.” nEVs are stem cell-derived particles that support cell-to-cell communication.

Cancer Exosomes

Exosomes are released in high quantities from rapidly growing cells, including all forms of cancer. It is known that cancer exosomes contribute to metastasis through intercellular communication.

Although exosomes are produced by all cells to facilitate bodily functions, on a cell-for-cell basis, cancer cells release larger quantities of exosomes.

Cancer exosomes are also unique, because they are surrounded by protein “ribbons” known as chaperones.  While these ribbons can vary in size and shape on the surface of exosomes from different types of rapidly growing cells, they are always present.

Because of exosomes exhibit biomarkers specific to the cancerous cells that have released them, exosomes also have great potential to be used within theranostic applications. Theranostics is a field of medicine that provides patient-specific therapy based on findings from targeted diagnostic tests.

Finally, cancer exosomes have great potential to be used within diagnostic tools and liquid biopsies for non-invasive detection of cancer.

In summary, there are three broad applications of exosomes in cancer:

  1. Exosomes facilitate cancer activity, including tumor formation (tumorigenesis), spread (metastasis), blood vessel growth (angiogenesis), and immune evasion
  2. Cancer exosomes can be used as biomarkers within diagnostic tools
  3. Cancer exosomes can be used to select targeted treatments for cancer patients based on their unique disease progression

Exosome Therapeutics

Exosomes are gaining momentum within the medical research community as a type of cell-free therapeutic. For many cell types, exosomes may provide the needed therapeutic effects without the risks of administering cells to patients.

For this reason, there are now more than a dozen companies developing therapeutics that leverage exosomes and other types of extracellular vesicles (EVs).

These companies include Aegle Therapeutics, Anjarium Biosciences, Capricor Therapeutics, Codiak Biosciences, Creative Medical Technology Holdings, Everkine Corporation, Evox Therapeutics, Exogenus Therapeutics, Kimera Labs, ReNeuron, and Unicyte AG (a subsidiary of Fresenius Medical Care), among others.

First EV Therapeutic Entering Human Trial

Aegle Therapeutics deserves recognition as the first extracellular vesicle (EV) company to be cleared by the FDA to enter clinical trials in humans.

In May 2018, Aegle announced that the FDA cleared its first Investigational New Drug (IND) application to initiate a clinical trial in severe second-degree burn patients. The company plans to launch a Phase 1/2a clinical trial of its lead product AGLE-102 in late 2018.

Aegle is utilizing allogeneic bone marrow mesenchymal stem cell (BM-MSC) derived extracellular vesicles. It has two products under development, AGLE-102 for burn treatment and AGLE-103 for the management of epidermolysis bullosa (EB).

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