Hypoxic-Core (HyCo) Spheroids Recapitulate Hallmarks of Clinical Hypoxia: A Simple Chip-Based Method for Translational Oncology

Hypoxia influences the biology and response of cancers. No user-friendly device allows the study of hypoxia on highly-controlled clinically-relevant tumor models. Here, we describe how hypoxic-core (HyCo) spheroids generated using our unique non-perfused microfluidic device recapitulate key clinical hallmarks of hypoxia in vitro. Our PDMS-made system can generate up to 240 spheroids naturally exhibiting a diffusion-driven hypoxic core in only 4 days, here from two sarcoma cell lines. Compared to smaller normoxic spheroids from the same cell lines, known hypoxia-related genes are upregulated in HyCo spheroids. In addition, HyCo spheroids display hallmark hypoxia-induced resistance to radiotherapy and chemotherapy, along with increased invasiveness. Finally, to demonstrate applications of our HyCo spheroids and on-chip framework in drug development, we used our HyCo-derived gene expression dataset to select a drug candidate (diethyl-pythiDC) and confirmed its effect on spheroid invasiveness. Our results suggest that HyCo spheroids can be efficiently used as translational tools to integrate hypoxia in cancer research, without complex workflows or setups. TeaserOn-chip spheroids with a natural hypoxic-core emulate clinical cancer hypoxia hallmarks essential for novel therapy development.