Soft Polyethylene Glycol Hydrogels Support Human PSC Pluripotency and Morphogenesis.

Area of Science:

• Developmental Biology
• Stem Cell Biology
• Biomaterials Science

Background:

• Lumenogenesis in the epiblast is crucial for human development but poorly understood due to in vivo study limitations.
• Human pluripotent stem cell (hPSC)-based models offer insights, but often use ill-defined matrices for 3D structure generation.
• The role of matrix mechanical cues, like elastic modulus, in early embryonic morphogenesis remains largely unexplored.

Purpose of the Study:

• To investigate the impact of synthetic matrix mechanical properties on human pluripotent stem cell (hPSC) morphogenesis.
• To elucidate the role of matrix stiffness in epiblast lumenogenesis and apico-basal polarization.
• To establish a modular platform for studying early human development using defined biomaterials.

Main Methods:

• Designed synthetic, nonadhesive polyethylene glycol (PEG) hydrogels with varying elastic moduli.
• Assessed hPSC viability, pluripotency, and differentiation across a range of hydrogel stiffnesses.
• Quantified lumen formation and apico-basal polarization in hPSC aggregates cultured on hydrogels of different moduli.

Main Results:

• Identified an optimal range of hydrogel moduli supporting hPSC viability, pluripotency, and differentiation.
• Demonstrated that intermediate stiffness hydrogels promoted the most epiblast-like aggregate formation and lumenogenesis.
• Observed that stiffer matrices inhibited lumen formation and polarization, while softer matrices led to aberrant structures.

Conclusions:

• Synthetic PEG hydrogels provide a tunable platform for studying hPSC morphogenesis and the influence of matrix mechanics.
• Matrix stiffness is a critical determinant of epiblast-like structure formation, lumenogenesis, and cellular polarization.
• This approach facilitates a deeper understanding of early human development and the role of the microenvironment.