Magnetic resonance experiments provide a non-invasive and powerful method to analyse molecules within cells and tissues. Diffusion methods are frequently used in MRI measurements to provide medical diagnoses, protein folding characterisation and localisation of biomolecules in cellular mixtures.There has been a number of significant advances in the field of diffusion methods for biological systems; nevertheless, the analysis of data in those systems is challenging due to the inherent heterogeneity inside cells and living tissues. A series of tailored models have addressed those challenges in both homogeneous and heterogeneous samples; however, a general method for cellular systems still seems to be required.
Researchers at Oxford have tackled this limitation with the development of INDIANA (IN-cell DIffusion ANAlysis), an experimental protocol and software package that offers a quick, accurate and general method for the characterisation of the following parameters in a cell suspension:
• Cell density and size
• Permeability
• Intrinsic relaxation rates
• Diffusion coefficients
The region of practical validity and the accuracy of the fitted parameters were determined and,optimised for the study of eukaryotic cells by NMR. Experimental endorsement of the model also proved the utility of the technology.
Applications of the method include:
• Analysis of any molecule that can be spectroscopically resolved – the isotopic enrichment would allow for background-free measurements
• Monitoring of cell preservation in perfusion systems
• Diffusion MRI