We developed an analytical routine to measure Cu isotope compositions of biomedical samples in situ using LA-MC-ICP-MS. Matrix-matched gelatin based Cu isotope standards were produced to correct for instrumental sources of isotope fractionation. Analyses of certified reference materials admixed with gelatin yielded accurate and precise Cu isotope compositions consistent with certified values advocating for measurements of biomedical samples. Thus, VX2 tumor cells in rabbit livers, a model system for human hepatocellular carcinoma (HCC) were analysed and showed distinct Cu isotope variations between tumor and healthy tissues agreeing with previous work on HCC biopsies.