Figure 2.

Structural Phenotyping of Stem Cell-Derived Cardiomyocytes

(A) α-actinin (white) and chromatin (blue) images of rpCMs at 6 (i), 24 (ii), and 48 hr (iii) as well as hiCMs at 72 hr (iv) after seeding with color-coded orientations and Fourier representations. Scale bar represents 25 μm.

(B) Scatter plot showing how our metrics of myofibrillar architecture quantitatively captured the progression of myofibrillogenesis in rpCM tissues from differentiated (6 hr, brown squares) to immature (24 hr, red circles) and finally mature (48 hr, green triangles) myocytes. In contrast, the hiCM tissues (orange diamonds) exhibited a relatively immature myofibrillar organization.

(C) A dataset comprising ∼120 sarcomeric α-actinin images per conditions (insets in Ai–Aiv) was acquired, and the features extracted from this dataset were utilized to train several classifiers to distinguish the classes of differentiated (D), immature (I), and mature (M) myocytes. The classifiers assigned only ∼29% of the 118 hiCM images to the class of myocytes with a mature structural phenotype, with the rest showing differentiated or immature contractile architectures.

Results are shown as mean ± SEM. See also Figure S4.