A method of preparation of a composition including extracellular vesicles (10) derived from stem cells mesenchymal isolated from chorion of human placenta, said method being including: a step of extraction of extracellular vesicles(10) from stem cells mesenchymal (5), said cells (5) being derived from chorion (C) in advance separated from the placenta (200) in a step of separation chorion-placenta (93), and a step (251, 252, 253) of sterilization and elimination of contaminating proteins from a semi-finished fluid containing said extracellular vesicles (10), wherein said step (251, 252, 253) of sterilization and elimination of contaminating proteins comprises a first step of ultracentrifugation (252, 253) of the said semi-finished fluid, and wherein said first step of ultracentrifugation (252) is performed following of a phase of filtration (251) of the said semi-finished fluid.
