By encapsulating si-survivin by electroporation, MSC EVs expressing CXC chemokine receptor type 4 (CXCR4) can specifically bind to the highly expressed stromal cell-derived factor-1 (SDF-1) on the tumor surface, reach the tumor site, knock down the survivin gene, and achieve a tumor-killing effect [120]. The gene discussed is BIRC5; the disease is neoplasm.