Well-defined growth factors promote cardiac development in axolotl mesodermal explants

Area of Science:

• Developmental biology
• Regenerative medicine
• Comparative embryology

Background:

• Cardiac mesoderm forms the heart during vertebrate embryonic development.
• Pharyngeal endoderm is known to induce cardiac mesoderm in urodeles.
• Early axolotl embryos require specific signaling for cardiac mesoderm differentiation.

Purpose of the Study:

• To investigate the role of growth factors in cardiac mesoderm formation in vitro.
• To identify specific growth factors that can enhance or inhibit heart tissue development.
• To understand the regulation of early vertebrate cardiac development.

Main Methods:

• Utilized an in vitro explant system with axolotl (Ambystoma mexicanum) embryos.
• Cultured prospective cardiac mesoderm explants from early neurula stages.
• Administered various growth factors, including TGF-β1, PDGF, and bFGF, to explants.
• Assessed the frequency of beating cardiac tissue formation as an indicator of successful differentiation.

Main Results:

• Explants from early neurula stages rarely formed cardiac tissue without added factors.
• Transforming growth factor beta-1 (TGF-β1) and platelet-derived growth factor BB (PDGF) significantly increased heart tissue formation.
• Basic fibroblast growth factor (bFGF) reduced cardiac tissue formation in explants from later stage embryos.
• Other tested growth factors did not enhance cardiac mesoderm development.

Conclusions:

• TGF-β1 and PDGF are potent stimulators of early cardiac mesoderm formation in axolotls.
• bFGF appears to play an inhibitory role in later stages of cardiac mesoderm development.
• These findings suggest conserved roles for TGF-β1, PDGF, and bFGF in regulating vertebrate heart development in vivo.