TP53 and hepatocellular carcinoma: The therapeutic efficiency of combined chemotherapy and gene therapy was evaluated on the human hepatocellular carcinoma cell line, HepG2, using double-walled microspheres that consisted of a poly (d,l-lactic-co-glycolic acid) (PLGA) core surrounded by a poly(l-lactic acid) shell layer to deliver DOX and/or chitosan-DNA NPs for delivering the gene encoding the p53 tumor suppressor protein (chi-p53) to the HepG2 cells.