In vitro chemosensitivity of feline injection site-associated sarcoma cell lines to carboplatin.

OBJECTIVE: To determine the in vitro chemosensitivity of feline injection site-associated sarcoma (FISAS) cells to carboplatin concentrations generated by elution of carboplatin-impregnated calcium sulfate hemihydrate (CI-CSH) beads.

STUDY DESIGN: In vitro study.

SAMPLE: Five immortalized cell lines from histologically confirmed, primary FISASs.

METHODS: For each cell line, one 96-well microplate was used for each time point (24, 48, 72 hours). In each microplate, 3 wells were seeded with ∼7.5 × 103 cells per well for every carboplatin treatment added, ranging from 5 to 450 µM. Microculture plates were incubated for 24, 48, or 72 hours. Drug efficacy was assessed via a bioreductive fluorometric assay. For apoptosis analysis, 3 wells were seeded with ∼5 × 104 cells per well for every carboplatin treatment added, ranging from 5 to 450 µM. Flow cytometry was performed and the relative percentages of viable, apoptotic, and late apoptotic/necrotic cells were reported. All experiments were run in triplicates.

RESULTS: Carboplatin exerted dose-dependent and time-dependent effects on FISAS cell viability. The IC50 values were within the range of carboplatin concentrations eluted from CI-CSH beads.

CONCLUSION: Elution of carboplatin from CI-CSH beads generate concentrations sufficient to result in 50% growth inhibition of FISAS cells in vitro. Local tumor control might be achieved by implantation of CI-CSH beads immediately following radical or marginal excision of the primary tumor or by implantation without tumor resection.