Oral Presentation ESA-SRB Conference 2015

Through the looking glass: what can we see in the early embryo when we look carefully enough (#63)

Martin Gosnell 1 2 , Melanie MC Dowall 3 4 , Ayad Anwer 2 , Jeremy Thompson 3 4 , Ewa Goldys 3
  1. Quantitative Pty Ltd, NSW, 2155
  2. ARC Centre of Excellence for Nanoscale Biophotonics, Macquarie University, North Ryde, NSW, Australia
  3. Robinson Research Institute, School of Paediatrics and Reproductive Health, The University of Adelaide, Medical School, Adelaide, Australia
  4. Australian Research Council Centre of Excellence for Nanoscale Biophotonics and Institute for Photonics and Advanced Sensing , The University of Adelaide, North Terrace, Adelaide, Australia

I will explain how to use subtle properties of cell colour to provide information about cell biochemistry. Crucially, the method is label free, avoiding biochemical interference with cells.  Our methodology is able to detect endogenous metabolites in biological specimens in a variety cells and tissue with highly discriminative results. The autofluorescent emission from these samples represent a mixture of spectral signatures from these compounds, measured under a range of specifically chosen excitation wavelengths. These are employed to generate a useful and biologically significant feature sets from which we can extract two or three highly informative feature variables highlighting the most interesting aspects of the data. Further we identify the abundance of these compounds at each pixel. We analyse all acquired cell images in a fully automated way without subjective choices. The process aims to derive maximum quantitative information from cell images, and statistics is used whenever required to assess population properties and differences.

I will present selected examples of applicability of this quantitative colour imaging method (1)  for differentiation of cells and for biochemically mapping key fluorophores in cell populations, including statistics of fluorophore content.; (3) for the detection of cell subpopulations answering the question of whether cells form distinguishable clusters; (4) for finding label-free signatures of cell subpopulations, which demonstrate that, in some cases, antibody labeling may in some cases be replaced by measurements and analysis of autofluorescent characteristics. These methods have been applied to several cell types including olfactory neuronal cells, adipose-derived stem cells before and after osteogenic differentiation, induced pluripotent stem (IPS) cells, motor neurone disease cells, various cancer cells (MCF10A and MCF7) and diabetic tissue. As an example,  in cells with a mitochondrial mutation, cellular maps of native fluorophores, flavins, bound and free NADH and retinoids unveiled subtle metabolic signatures and helped uncover medically significant cell subpopulations, in particular, a subpopulation with simultaneous low bound NADH, high free NADH and high lipofuscin content.

I will also show the application of this new type of label-free imaging and image analysis to the early embryos.