Friday April 22
Chem. Sci. & Engineering Room 211
Presenter: Dr. Brenda M. Ogle, Assistant Professor Biomedical Engineering University of WisconsinMadison
Abstract: Advances in cell research and cell therapies, such as repair of cardiac tissue following infarction, depend on technologies that accurately and non-invasively assess cell state, both as single cells and as 3D entities, with the potential to sort populations based on this assessment. Defining intrinsic biomarkers that characterize stem cell state advances this goal by reducing the need for extrinsic labels. Several pieces of evidence suggest that pluripotent cells are metabolically different than differentiated cells. Therefore, we propose that endogenous fluorophores, which are often involved in key metabolic processes and are noninvasively detectable by advanced optical methods, would exhibit different fluorescent properties in pluripotent cells than in their differentiated counterparts, thereby serving as a unique, intrinsic indicators of differentiation state. Indeed, we have identified changes in the fluorescent properties of stem cells during differentiation, utilizing multiphoton optical analysis, with its ability to probe deep within multicellular aggregates, and Fluorescence Lifetime Imaging. Using a wavelength to excite nicotinamide adenine dinucleotide (NADH) we found that the fluorescence lifetime of NADH decreases during the initial timecourse of differentiation, in both mouse and human embryonic stem cells. Furthermore, cardiomyocytes developed from human embryonic stem cells exhibit longer fluorescence lifetimes than non-beating cells. We are currently combining these observations with a modular, stage-mounted multiphoton flow cytometry system that could ultimately sort cellular aggregates, such as embryoid bodies or engineered constructs, based on such endogenous fluorescence signatures.