Liposomal Doxorubicin Kinetic Study in an In vitro 2D and 3D Tumor Model for Osteosarcoma in a Perfusion Bioreactor

Background: In vivo drug screening in animal models is contrary to ethical values, costly and time-consuming. Traditional static in vitro models do not reflect the basic characteristics of bone tumor microenvironments; therefore, perfusion bioreactors, in particular, would be an applicable choice due to their advantages to regenerate versatile bone tumor models for studying in vitro novel drug delivery systems. Methods: In this study, an optimal drug formulation of liposomal doxorubicin was prepared, and the release kinetics of the drug and its toxicity effect on MG-63 bone cancer cell line were investigated in two-dimensional, static three-dimensional media on a PLGA/β-TCP scaffold and also in a dynamic media in a perfusion bioreactor. In this assay, the efficacy of the IC50 of this formulation which had been obtained in two-dimensional cell culture (= 0.1 μg/ml), was studied in static and dynamic threedimensional media after 3 and 7 days. Liposomes with good morphology and encapsulation efficiency of 95% had release kinetics of the Korsmeyer-Peppas model. Results: The results of cell growth before treatment and cell viability after treatment in all three environments were compared. Cell growth in 2D was rapid, while it was slow in static 3D conditions. In the dynamic 3D environment, it was significant compared to the static tumor models. Cell viability after 3 and 7 days from treatment was 54.73% and 13.39% in 2D conditions, 72.27% and 26.78% in the static 3D model, while 100% and 78.92% in the dynamic culture indicating the effect of drug toxicity over time, but drug resistance of 3D models compared to 2D culture. In the bioreactor, the formulation used in the mentioned concentration showed very small cytotoxicity demonstrating the dominance of mechanical stimuli on cell growth over drug toxicity. Conclusion: Increasing drug resistance in 3D models compared to 2D models indicates the superiority of liposomal Dox over free form to reduce IC50 concentration.