Exosomes are nanoscale extracellular vesicles - very small packages of signalling information one-thousandth the size of a cell. They are produced by virtually every cell type as a means of intercellular communication. This natural paracrine signaling system allows a healthy body to run like a well-oiled machine.
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 the same type of membrane as their parent cells, exosomes protect these exosomal proteins and miRNA from degradation until they are delivered to the target cell.
When exosomes deliver their contents to target cells, exosomal proteins can have direct effects on intracellular processes and signaling. Exosomal mRNA may be translated by the target cell to produce numerous copies of the regenerative protein. Exosomal miRNA influences target cell protein production by interfering with specific endogenous protein production. Exosomal signaling can also alter target cell exosome loading for cascading effects and a more sustained effect than the type of proteins in PRP or amniotic fluid alone.
Mesenchymal Stem Cell Exosomes
This very unique type of exosomes are produced by stem cells of the connective tissue lineage – the origin of skin, hair, bone, muscle, cartilage etc. MSC exosomes are very different from exosomes found in adult bone marrow, which has a preponderance of hematopoietic stem cell exosomes, or amniotic fluid, which has primarily maternal epithelial cell exosomes. The distinct ability of MSC exosomes to induce connective tissue synthesis may be the basis of what has been observed with stem cell therapy.
Advantages of Young Progenitor Cells
As we age, the number and function of the MSCs in our tissues declines sharply. Aged autologous progenitor cells produce about 30% of the cytokines and significantly different miRNAs compared with perinatal MSCs. This substantial difference in secretome confers a significant advantage of peri-natal MSC exosomes over exosomes from aged autologous or allogeneic progenitor cells.
Effects of MSC exosomes on Skin
* Stimulate fibroblast proliferation and migration;
* Increase collagen extracellular matrix production/deposition;
* Regulate tissue remodeling to reduce scarring;
* Increase the number of hair follicles in the growth phase;
* Regenerate dermal papilla cells of hair follicle.
MSC exosomes down-regulate inflammatory proteins and upregulate anti-in-flammatory proteins.
Exosomes stimulate the proliferation and migration of cells such as fibroblasts, endothelial cells, keratinocytes and specific endogenous progenitor cells. This increases angiogenesis (new blood vessel formation), improves survival of damaged tissues and reduces scarring.
Tissue Regeneration & Remodeling
Exosomes derived from mesenchymal stem cells have been shown to reduce apoptosis (programmed cell death), which could lead to less tissue damage in response to disease or injury. MSC Exosomes have the capacity to enhance tissue remodeling by promoting a normal lattice-structure of collagen fibers for reduced scarring and more normal healing.