ASSESSMENT OF METABOLISM AND VIABILITY IN LIVE-3D BRAIN ORGANOIDS WITHIN A CUSTOM BIOREACTOR FOR ULTRA-HIGH-FIELD MRI/MRS

The development of three-dimensional organoid culture over the past decade has enabled researchers to outreach the possibility to study cellular and molecular mechanisms in cells within their complex environment. Indeed, its accurate reproduction of the organization of brain cells makes it a relevant model for studying the development, physiology and maturation of the brain.
However, we still lack methods to follow metabolism in this model longitudinally, non-invasively. To tackle this, we developed an in-house-designed bioreactor adapted to preclinical horizontal-bore MR scanner to maintain organoids under controlled environmental conditions throughout the scan. The aims of this project are first to maintain the cellular integrity and viability of the organoids over a 6-hour MR-imaging period in the bioreactor, and then to study the metabolism of the organoids using proton magnetic resonance spectroscopy (¹H-MRS).
The organoids were obtained by dissection of 15-fetal-day-old rats’ embryos telencephales using Honneger’s protocol and normal culture conditions were maintained during the MR-scan by circulating culture medium at 1 mL/min through the bioreactor.
We were able to characterize metabolic profile inside organoids using ¹H-MRS spectra which suggest an early stage of development. We confirmed these metabolic data with ¹H-NMR and mass spectrometry and assessed organoids viability using propidium iodide dye to ensure that we maintained the organoids alive during the MR scan.
Next steps will be to study the metabolism and the microstructure of these organoids along their development both using MRS and diffusion-weighted MRI/MRS techniques and histological analysis; but also, in a context of neurodevelopment disease.