Autofluorescence and metabolic signatures in a pig model of differentiation based on induced pluripotent cells and embryonic bodies

Besides several genetic and molecular markers, stem cells undergoing differentiation show changes in their metabolic engagement, such as a switch from anaerobic to aerobic energetic metabolism and decreased autophagic activity, representing metabolic signatures of the stemness status. These activities involve biomolecules - respectively NAD(P)H and flavins, and lipofuscin-like lipopigments- that give rise to autofluorescence (AF) emission under suitable excitation light conditions. Since these endogenous fluorophores can be exploited as cell intrinsic biomarkers, attention is currently deserved to assess the potential of AF analysis to monitor the cell stemness status or maturation degree into a desired phenotype. In our work, we employed pig induced pluripotent stem (iPS) cell as a model of differentiation to compare their AF properties in living conditions with those of embryoid bodies (EBs) derived from them, by means of imaging, microspectrofluorometric techniques and spectral fitting analysis. The AF results indicate that reprogramming of suine iPS cells do not lead to typical metabolic functions of the undifferentiated status. These findings support the value of AF analysis as a tool for a comprehensive assessment of the actual stem cells Differentiation degree in the development of regenerative medicine strategies, and for application to animal species of interest in veterinary, zootechnology and, in general, to the species for which immunomarkers are not yet available.