Mechanically and Chemically Defined PEG Hydrogels Improve Reproducibility in Human Cardioid Development

Area of Science:

• Cardiovascular Research
• Biomaterials Science
• Stem Cell Biology

Background:

• Cardioids, derived from human induced pluripotent stem cells (hiPSCs), are promising heart organoids but face reproducibility challenges in current culture methods (suspension or Matrigel).
• Existing methods limit widespread use in research and clinical applications due to variability.

Purpose of the Study:

• To investigate the use of synthetic, matrix metalloproteinase (MMP)-degradable polyethylene glycol (PEG)-based hydrogels for cardioid culture.
• To determine the impact of mechanical and biochemical cues within these hydrogels on cardioid development and function.

Main Methods:

• Cardioids were cultured in various PEG-based hydrogel formulations with defined stiffness and RGD peptide concentrations.
• Morphological development, tissue function, and gene expression were analyzed and compared to Matrigel and suspension cultures.
• The role of matrix stiffness and cell adhesion motifs was assessed.

Main Results:

• Successful cardiac differentiation was achieved in all tested hydrogel conditions.
• Cardioids in optimized PEG hydrogels (3 wt.% PEG-2mM RGD) showed comparable morphology and function to Matrigel-cultured cardioids.
• Matrix stiffness and RGD concentration significantly influenced cardioid development, chamber formation, contractile physiology, and endothelial gene expression.
• PEG hydrogels demonstrated improved reproducibility of cardioid properties compared to traditional methods.

Conclusions:

• Synthetic PEG hydrogels provide a tunable and reproducible platform for human cardioid culture.
• These hydrogels represent a viable alternative to Matrigel, with potential applications in cell therapy and tissue engineering.
• Mechanical and biochemical properties of the hydrogel microenvironment are critical for directing cardioid development.