Noninvasive Quantification of Cell Density in Three-Dimensional Gels by MRI

• Published in: IEEE transactions on biomedical engineering 2019-03, Vol.66 (3), p.821-830
• Main Authors: Archer, Brian J., Wessling, Matthias, Iruela-Arispe, M. Luisa, Bouchard, Louis-S., Uberruck, Till, Mack, Julia J., Youssef, Khalid, Jarenwattananon, Nanette N., Rall, Deniz, Wypysek, Denis, Wiese, Martin, Blumich, Bernhard
• Format: Article
• Language: English
• Subjects: Biomedical measurement; bioreactor; Bioreactors; Calibration; Cell Count - methods; Cell culture; Cell density; Cell growth; Cell mapping method; Cells, Cultured; Correlation; Density; Gels; HEK293 Cells; Humans; hydrogel; Hydrogels; Hydrogels - chemistry; Imaging, Three-Dimensional - methods; Magnetic resonance imaging; Magnetic Resonance Spectroscopy - methods; Microscopy; MRI; NMR; Nuclear magnetic resonance; Opacity; Optical microscopy; Optics; Parameter sensitivity; Saccharomyces cerevisiae - cytology; Signal Processing, Computer-Assisted; Three-dimensional displays; Tissue culture; Tissue Engineering; Weighting
• ISSN: 0018-9294; 1558-2531
• DOI: 10.1109/TBME.2018.2857443

Objective: For tissue engineering, there is a need for quantitative methods to map cell density inside three-dimensional (3-D) bioreactors to assess tissue growth over time. The current cell mapping methods in 2-D cultures are based on optical microscopy. However, optical methods fail in 3-D due to increased opacity of the tissue. We present an approach for measuring the density of cells embedded in a hydrogel to generate quantitative maps of cell density in a living, 3-D tissue culture sample. Methods: Quantification of cell density was obtained by calibrating the 1 H T 2 , magnetization transfer (MT) and diffusion-weighted nuclear magnetic resonance (NMR) signals to samples of known cell density. Maps of cell density were generated by weighting NMR images by these parameters post-calibration. Results: The highest sensitivity weighting arose from MT experiments, which yielded a limit of detection (LOD) of 2.5 × 10 8 cells/mL/√Hz in a 400 MHz (9.4 T) magnet. Conclusion: This mapping technique provides a noninvasive means of visualizing cell growth within optically opaque bioreactors. Significance: We anticipate that such readouts of tissue culture growth will provide valuable feedback for controlled cell growth in bioreactors.