Complex temporal regulation of capillary morphogenesis by fibroblasts

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Cell Biology

Background:

• Endothelial and stromal cell interactions are crucial for tissue vascularization.
• Fibroblasts (FBs) influence angiogenesis, matrix remodeling, and fibrosis.
• Self-assembling peptide nanofibers offer a tunable microenvironment for regenerative medicine.

Purpose of the Study:

• To quantify the dual role of fibroblasts in angiogenesis within a peptide nanofiber model.
• To investigate chemical (growth factor expression) and mechanical (scaffold remodeling) contributions of FBs.
• To understand EC-FB interactions in a 3D biomaterial context for cardiac regeneration.

Main Methods:

• Culturing human microvascular endothelial cells (ECs) and FBs, or co-cultures, in 3D peptide nanofibers for up to 6 days.
• Assessing cell migration, capillary network formation, and cell survival.
• Quantifying growth factor expression (VEGF, Ang-1), matrix metalloproteinase (MMP-2) activity, and collagen I deposition.
• Measuring construct stiffness and scaffold integrity.

Main Results:

• Peptide nanofibers supported EC migration, network formation, and survival without significant degradation.
• FBs promoted early capillary network formation by enhancing EC migration and upregulating vascular endothelial growth factor (VEGF) and Angiopoietin-1 (Ang-1).
• EC-FB co-cultures modulated FB MMP-2 expression, increased collagen I deposition, leading to enhanced construct stiffness and microenvironment stability.

Conclusions:

• Fibroblasts are vital for initial angiogenesis, especially without external stimulation.
• Coordinated EC-FB interactions are necessary for balancing matrix deposition and remodeling in later stages.
• Developing biomaterial microenvironments that support cell-cell interactions and migration is key for effective cardiac regeneration strategies.