Oxygen supply and oxygen-dependent gene expression in differentiating embryonic stem cells

Area of Science:

• Developmental Biology
• Stem Cell Biology
• Hypoxia Research

Background:

• Embryoid bodies (EBs) derived from mouse embryonic stem cells mimic early murine embryogenesis in vitro.
• Understanding oxygen dynamics is crucial for early developmental stages, particularly the preimplantation conceptus in a low-oxygen environment.

Purpose of the Study:

• To investigate oxygen supply, consumption, and response to hypoxia in embryoid bodies during early development.
• To assess the utility of embryoid bodies as a model for studying oxygen-regulated gene expression in embryogenesis.

Main Methods:

• Culture of embryoid bodies under normoxic (20% O2) and hypoxic (1% O2) conditions.
• Microelectrode measurements of pericellular oxygen tension.
• Confocal laser scanning microscopy for cell viability assessment.
• Quantitative analysis of aldolase A and vascular endothelial growth factor (VEGF) mRNA levels.

Main Results:

• Embryoid bodies exhibited comparable growth under both normoxic and hypoxic conditions.
• Efficient oxygenation of the core region was observed in 13- to 14-day-old EBs.
• Viability of cells within EBs was confirmed using fluorescent staining.
• Exposure to hypoxia (1% O2) led to increased aldolase A and VEGF mRNA levels in 8- to 9-day-old EBs.

Conclusions:

• Embryoid bodies are a robust in vitro model for studying early developmental responses to oxygen levels.
• EBs demonstrate the ability to sense and respond to hypoxic conditions by modulating specific gene expression.
• This model system is valuable for exploring oxygen-regulated gene expression during early embryogenesis.