A DIY Bioreactor for in Situ Metabolic Tracking in 3D Cell Models via Hyperpolarized ¹³C NMR Spectroscopy

Nuclear magnetic resonance (NMR) spectroscopy is a valuable diagnostic tool limited by low sensitivity due to low nuclear spin polarization. Hyperpolarization techniques, such as dissolution dynamic nuclear polarization, significantly enhance sensitivity, enabling real-time tracking of cellular metabolism. However, traditional high-field NMR systems and bioreactor platforms pose challenges, including the need for specialized equipment and fixed sample volumes. This study introduces a scalable, 3D-printed bioreactor platform compatible with low-field NMR spectrometers, designed to accommodate bioengineered 3D cell models. The bioreactor is fabricated using biocompatible materials and features a microfluidic system for media recirculation, ensuring optimal culture conditions during NMR acquisition and cell maintenance. We characterized the NMR compatibility of the bioreactor components and confirmed minimal signal distortion. The bioreactor's efficacy was validated using HeLa and HepG2 cells, demonstrating prolonged cell viability and enhanced metabolic activity in 3D cultures compared to 2D cultures. Hyperpolarized [1-¹³C] pyruvate experiments revealed distinct metabolic profiles for the two cell types, highlighting the bioreactor's ability to discern metabolic profiles among samples. Our results indicate that the bioreactor platform supports the maintenance and analysis of 3D cell models in NMR studies, offering a versatile and accessible tool for metabolic and biochemical research in tissue engineering. This platform bridges the gap between advanced cellular models and NMR spectroscopy, providing a robust framework for future applications in nonspecialized laboratories. The design files for the 3D printed components are shared within the text for easy download and customization, promoting their use and adaptation for further applications.