Second harmonic generation microscopy of early embryonic mouse hearts

Area of Science:

• Developmental Biology
• Biophysics
• Cardiovascular Research

Background:

• Extracellular matrix (ECM), especially fibrillar collagen, is vital for heart biomechanics, influencing tissue properties and function.
• Understanding early heart development is key to managing congenital cardiovascular defects and embryonic cardiac failures.

Purpose of the Study:

• To investigate the role of biomechanical regulation in early embryonic heart development using mouse models.
• To explore second harmonic generation (SHG) microscopy for visualizing cardiac ECM development.

Main Methods:

• Utilized second harmonic generation (SHG) microscopy to visualize fibrillar collagen in developing mouse embryos.
• Correlated SHG imaging with measurements of cardiac contractility.
• Employed simultaneous volumetric SHG and two-photon excitation microscopy with EGFP reporter.

Main Results:

• Observed a significant increase in SHG-positive fibrillar content and organization within 24 hours of initiating heart contractions.
• Found higher fibrillar organization in areas of greater contractility.
• Detected reduced fibrillar content and organization in a mouse model with impaired cardiac contractility (Mlc2a).

Conclusions:

• Mechanical load plays a regulatory role in the production and organization of structural fibers from the earliest stages of cardiogenesis.
• SHG microscopy is a valuable, non-biased tool for investigating embryonic cardiogenesis and biomechanics.