Characterization of mitochondrial populations during stem cell differentiation.

Mitochondrial dynamics play an important role in numerous physiological and pathophysiological phenomena in the developing and adult human heart. Alterations in structural aspects of cellular mitochondrial composition as a function of changes in physiology can easily be visualized using fluorescence microscopy. Commonly, mitochondrial location, number, and morphology are reported qualitatively due to the lack of automated and user-friendly computer-based analysis tools. Mitochondrial Quantification using MATLAB (MQM) is a computer-based tool to quantitatively assess these parameters by analyzing fluorescently labeled mitochondria within the cell; in particular, MQM provides numerical information on the number, area, and location of mitochondria within a cell in a time-efficient, automated, and unbiased way. This chapter describes the use of MQM's capabilities to quantify mitochondrial changes during human pluripotent stem cell (hPSC) differentiation into spontaneously contracting cardiomyocytes (SC-CMs), which follows physiological pathways of human heart development.