Exosomes are nano-sized biovesicles released into surrounding body fluids upon fusion of multivesicular bodies and the plasma membrane.
They were shown to carry cell-specific cargos of proteins, lipids, and genetic materials, and can be selectively taken up by neighboring or distant cells far from their release, reprogramming the recipient cells upon their bioactive compounds. Therefore, the regulated formation of exosomes, specific makeup of their cargo, cell-targeting specificity are of immense biological interest considering extremely high potential of exosomes as non-invasive diagnostic biomarkers, as well as therapeutic nanocarriers.
The exosomes are also called intraluminal vesicles and are found in various tissues and body fluids (5-7). Expand
Sourcing and safety*
The exosomes derived from mesenchymal stem cells (MSCs) are of prime importance due to the greater therapeutic and regenerative potential as shown in Figure 4. Due to the challenges faced in isolating exosomes from various body fluids, regenerative and translational medicine experts used MSC-derived exosomes for treating various disorders (2). MSCs derived exosomal cargo exhibit intracellular signaling and communications to targeted tissues. The key sources of exosomes derived from the MSCs include bone marrow, adipose tissue, placental cells, umbilical cells, endometrial fluid, and amniotic fluid (2, 100 ).
Exosomes of MSC origin have cell surface markers such as CD 29, CD 44, and CD 73 embedded in them (100). They play a vital role in the biomechanisms involved in the repair and regeneration, bioenergetics, immunoregulation, intracellular communication, and tissue metabolism (2, 101 ). In a proteomic analysis, a total of 730 protein molecules in bone marrow MSC derived exosomes were isolated (102). Some researchers found the existence of transcription signaling factors in exosomal cargoes (103). Amniotic fluid exosomes are the most preferred exosomes for clinical applications than bone marrow-derived exosomes (104).
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