Figure 1.

(A) Biogenesis, secretion, and cellular uptake of exosomes. The biogenesis of exosomes starts from the (i) early endosomes which mature into (ii) late endosome, then (iii) multivesicular bodies are formed by the invagination of late endosomal membrane, which is finally secreted as (iv) exosomes to the extracellular matrix in a mesenchymal stem cell. (B) The secreted exosomes are uptaken by a recipient cell in several ways viz. (a) clathrin-mediated uptake, (b) receptor-mediated uptake or by the (c) membrane fusion event.