They are produced by virtually every cell type as a means of intercellular communication. Exosomes contain proteins such as growth factors, enzymes, receptors, transcription factors and matrix proteins that govern cell structure, function and signaling. They also contain messenger RNA (mRNA), the blueprint for protein production, and micro RNA (miRNA), an important intracellular signaling mediator. Having a similar membrane to their parent cells, exosomes protect these encapsulated proteins and miRNA
from degradation until they are delivered to a target cell. When exosomes deliver their contents to target cells, the exosomal proteins have direct effects on intracellular processes and signaling. Exosomal mRNA is translated by the cell to produce numerous copies of proteins that influence target cell behavior, signaling and its own exosome production. Exosomal miRNA influences target cell protein production by interfering with translation of specific mRNAs and reducing the production of
the corresponding proteins. Internalization of exosomal proteins and RNA also influences the production of exosomes by the target cell. The exosomes that are produced by the target cell, after internalization of the parent cell exosomes, will then have secondary effects on other cells. These cascading effects may be responsible for the more sustained biologic effects seen with exosomes than the effects that the type of proteins in PRP or amniotic fluid alone would have.