Cardiomyocytes derived from human embryonic and induced pluripotent stem cells: comparative ultrastructure.
Bottom Line: Noteworthy, the SR is less developed in HFKT-iPSC-CM.We also found in both cell types: (1) 'Ca(2+)-release units', which connect the peripheral sarcoplasmic reticulum with plasmalemma; and (2) intercellular junctions, which mimic intercalated disks (desmosomes and fascia adherens).In conclusion, iPSC and hESC differentiate into cardiomyocytes of comparable ultrastructure, thus supporting the notion that iPSC offer a viable option for an autologous cell source for cardiac regenerative therapy.
Affiliation: Victor Babeş National Institute of Pathology, Bucharest, Romania.Show MeSH
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Mentions: Light microscopy inspection of semi-thin sections from resin-embedded samples revealed EBs as spherical dense cellular colonies in both HFKT-iPSC-CM (Fig. 2A) and hESC-CM (Fig. 2B). As shown in Figure 3 (blue sections, insets), the cells in the periphery of the EB were elongated with a rod-shaped morphology, and often a clear cross-striations pattern of myofibrils was visible in the cytoplasm (Fig. 3). In contrast, the centrally-located cardiomyocytes were densely packed, round-shaped, with no visible striations, but with numerous lipid vacuoles and glycogen content (Fig. 4, blue sections, insets). Electron microscopy showed that all EBs contain similar cells with ultrastructural features of cardiomyocytes (Figs 3 and 4) surrounded by a monolayer of epithelial cells. The HFKT-iPSC-CM (Fig. 3A) and hESC-CM (Fig. 3B) from the EBs periphery were more elongated than cells in the centre which had an irregular shape with a round oval cellular body and short intermeshed cellular processes (Fig. 4A and B). Small cellular spaces containing collagen fibrils and cellular debris were present in between differentiated cardiomyocytes in the centre of EBs. The nuclei of the cardiomyocytes were more oval in the periphery (Fig. 3) than in the centre (Fig. 4) of the EBs where they showed a slightly irregular contour.
Affiliation: Victor Babeş National Institute of Pathology, Bucharest, Romania.