Monitoring the maturation of the sarcomere network: a super-resolution microscopy-based approach

Area of Science:

• Cardiology
• Stem Cell Biology
• Biomedical Imaging

Background:

• Induced pluripotent stem cells (iPSC) are crucial for cardiac research, but their maturation remains a challenge.
• Maturation involves sarcomere formation, essential for cardiomyocyte contraction and function.
• Current methods lack precise quantitative evaluation of sarcomere development.

Purpose of the Study:

• To establish an imaging-based strategy for quantitative assessment of sarcomere maturation in iPSC-derived cardiomyocytes.
• To evaluate the impact of culture conditions, such as patterned surfaces and extended cultivation, on sarcomere development.
• To validate the method using adult and neonatal heart cells as controls and extend its application to skeletal muscle cells.

Main Methods:

• Generated human iPSC-derived cardiomyocytes and cultured them under various conditions, including micro-patterned surfaces and prolonged time.
• Acquired super-resolution microscopy images of α-actinin to visualize sarcomere structures.
• Quantitatively analyzed cell morphology, sarcomere density, filament alignment, z-Disc thickness, and sarcomere length using image analysis and machine learning.

Main Results:

• Culturing iPSC-derived cardiomyocytes on line-shaped patterned surfaces significantly improved sarcomere content and filament orientation.
• Prolonged cultivation time enhanced structural maturation, promoting a more adult-like cardiomyocyte phenotype.
• The imaging workflow was successfully applied to skeletal muscle cells, demonstrating its versatility.

Conclusions:

• The developed imaging-based workflow provides a straightforward tool for quantitative evaluation of contractile cell structural maturation.
• This method can aid in optimizing differentiation protocols to improve sarcomere formation and maturity in iPSC-derived cells.
• Enhanced sarcomere maturation in iPSC-derived cardiomyocytes is achievable through optimized culture conditions, benefiting cardiac disease modeling and regenerative medicine.