CXCL8 and ovarian cancer: In some types of cancer, the signaling mediated by IL-8 and its receptor CXCR1 (C-X-C chemokine receptor type 1) is associated with CSCs properties [55,56,57]; therefore, the induction of IL-8 secretion by MSCs mediated by sEV-OCS could be support the self-renewal and maintenance of the CSCs niche in ovarian cancer.