Microdissected Tissue vs. Tissue Slices—A Comparative Study of Tumor Explant Models Cultured On-Chip and Off-Chip

SIMPLE SUMMARY: Cancer drugs have the lowest success rate of approval in drug development programs. In order to address this, predictive preclinical assays that correctly reflect the clinical efficacy of a drug represent an urgent need in both clinical oncology and pharmaceutical research. To address this need, multiple tumor models have been developed, including tumor explant culture platforms, which are the only models that preserve the integrity of the tumor tissue. However, these models have not been fully characterized and multiple variables exist between studies. We investigated the effect of tissue size and culture vessel type on the survival of tumor explants by comparing micro-dissected tumor tissue with corresponding tumor slices. Our results show that the model geometry and culture vessel affect proliferation, apoptosis, and hypoxia in tissue cultures, and must be considered in designing tumor explant culture platforms. ABSTRACT: Predicting patient responses to anticancer drugs is a major challenge both at the drug development stage and during cancer treatment. Tumor explant culture platforms (TECPs) preserve the native tissue architecture and are well-suited for drug response assays. However, tissue longevity in these models is relatively low. Several methodologies have been developed to address this issue, although no study has compared their efficacy in a controlled fashion. We investigated the effect of two variables in TECPs, specifically, the tissue size and culture vessel on tissue survival using micro-dissected tumor tissue (MDT) and tissue slices which were cultured in microfluidic chips and plastic well plates. Tumor models were produced from ovarian and prostate cancer cell line xenografts and were matched in terms of the specimen, total volume of tissue, and respective volume of medium in each culture system. We examined morphology, viability, and hypoxia in the various tumor models. Our observations suggest that the viability and proliferative capacity of MDTs were not affected during the time course of the experiments. In contrast, tissue slices had reduced proliferation and showed increased cell death and hypoxia under both culture conditions. Tissue slices cultured in microfluidic devices had a lower degree of hypoxia compared to those in 96-well plates. Globally, our results show that tissue slices have lower survival rates compared to MDTs due to inherent diffusion limitations, and that microfluidic devices may decrease hypoxia in tumor models.