CD34 and teratoma: These findings are significant because exosomes are not only more convenient to use but are also safer than cells, which are associated with immune rejection and possible formation of teratoma in vivo.40 The bi‐lipid layer of exosomes functions as a natural shield for functional molecules within the vesicle.41 As we have suggested before, exosomes are influenced by both dominant and recessive imprinting of their parent cells.42 It was shown that human CD34+ stem cell‐derived exosomes improved ischaemic limb perfusion, capillary density and motor function.