Substrate stiffness-dependent metabolic reprogramming of iPSC-derived cardiomyocytes on physiological PDMS polymers

Area of Science:

• Cardiovascular Research
• Cellular Metabolism
• Biomaterials Science

Background:

• Cardiac pathologies involve increased myocardial stiffness due to extracellular matrix (ECM) deposition.
• Cardiomyocyte (CM) metabolism shifts from fatty acid oxidation in healthy hearts to glucose utilization in diseased states.
• The impact of ECM stiffness on CM metabolic shifts remains understudied.

Purpose of the Study:

• To investigate the effect of varying extracellular matrix (ECM) stiffness on induced pluripotent stem cell-derived cardiomyocyte (iPSC-CM) metabolism.
• To compare iPSC-CM metabolism on physiological stiffness substrates versus traditional cell culture plastics.

Main Methods:

• iPSC-CMs were cultured on polydimethylsiloxane (PDMS) substrates with healthy (20 kPa) and fibrotic (130 kPa) stiffness, and on plastic.
• Metabolic analysis was performed using isotope-labeled mass spectrometry with central carbon tracing.
• Real-time cellular bioenergetics were assessed via extracellular flux analysis.

Main Results:

• Mass spectrometry revealed increased glucose utilization in iPSC-CMs cultured on plastic compared to softer PDMS substrates.
• Extracellular flux analysis showed greater lactic acid efflux from iPSC-CMs on plastic, indicating increased glycolytic flux.
• These findings suggest a shift towards aerobic glycolysis on stiff, non-physiological substrates.

Conclusions:

• Culture of iPSC-CMs on standard cell culture plastics induces a pathological metabolic profile.
• Physiological substrates are crucial for accurate assessment of cardiomyocyte metabolism, especially in disease modeling.
• This highlights the importance of substrate properties in studying cardiac cell metabolism and disease.