Fibroblast behavior in the embryonic chick heart

Area of Science:

• Developmental biology
• Cell biology
• Cardiac tissue engineering

Background:

• Intracardiac fibroblasts in chick embryos exist in two main populations: epicardial and atrioventricular.
• These fibroblast populations display differing characteristics in vivo regarding matrix production, proliferation, and interaction with myocytes.

Purpose of the Study:

• To investigate whether the distinct behaviors of epicardial and atrioventricular fibroblasts are predetermined or environmentally responsive.
• To elucidate the role of the local microenvironment in modulating fibroblast behavior during heart development.

Main Methods:

• Isolation of epicardial and atrioventricular fibroblast populations from Hamburger and Hamilton stage 36 chick hearts.
• Utilized a 3D cell aggregate culture system to simulate in vivo cell-cell and cell-matrix interactions.
• Cultured fibroblasts in serum-free medium and medium supplemented with chicken serum to assess environmental influences.

Main Results:

• In serum-free conditions, both fibroblast types showed low matrix production, minimal proliferation, and failed to segregate from myocytes.
• In the presence of chicken serum, both populations exhibited increased matrix production, heightened cell proliferation, and segregation from myocytes.
• These findings indicate that environmental factors significantly influence fibroblast behavior.

Conclusions:

• The observed differences between epicardial and atrioventricular fibroblasts in vivo are likely due to reversible responses to local environmental cues.
• Fibroblast behavior is not dictated by irreversible differentiation states but is plastic and adaptable to microenvironmental conditions.
• This suggests a dynamic model for fibroblast function in cardiac development and potentially in cardiac repair.