Comparing Cisplatin Sensitivity in Conventional 2D Versus Biomaterialfree 3D Spheroid Cultures of Human Cancer and...

Bone metastases represent a devastating complication of primary cancers, significantly impacting patient survival and quality of life. Accelerating the development of novel and effective chemotherapeutic drugs requires reliable in vitro models. Current in vitro models largely rely on conventional 2D set-ups, while 3D spheroid cultures are emerging. However, the correlation between these 2D and 3D configurations regarding chemotherapeutic efficacy remains poorly defined due to discrepancies in cellular assessment methodologies. To achieve a direct, unconfounded comparison of cellular responses to cisplatin treatment, identical analytical assays were deployed across both 2D and 3D culture models.

Cisplatin sensitivity was comparatively evaluated in metastatic human cancer cell lines (PC3 prostate adenocarcinoma and MDA-MB-231 breast adenocarcinoma) cultured in conventional 2D monolayers versus biomaterial-free 3D spheroids. Proliferation and viability assays were used to assess cytotoxicity, with human Bone Marrow Stromal Cells (hBMSCs) as non-malignant controls. Additionally, the effects of acute (24-hour) versus continuous cisplatin exposure regimens on cellular behavior were examined, and drug sensitivity was subsequently correlated with cell doubling time.

For all cell types, 3D spheroid cultures exhibited significantly lower sensitivities to cisplatin compared to 2D cultures. This is likely related to both the dimensionality of the 3D spheroids, as evidenced by time- and concentration-dependent cisplatin penetration into hBMSC spheroids, and cell proliferation, as a correlation between cisplatin sensitivity and cell doubling time was observed across the various cell types used. Finally, we showed that continuous exposure to cisplatin affects cell viability in 2D and 3D culture models in a manner comparable to limited exposure during the initial 24 hours of culture, and that cisplatin sensitivity correlates with cell doubling time.

Methodological similarities in analyzing cell viability were maintained for both 2D and 3D cell culture models when exploring cisplatin. Their dimensionality hampers penetration of cisplatin into the core of 3D spheroids.

Overall, our data underscore the dependence of cisplatin sensitivity on the dimensionality of in vitro models (2D vs. 3D.