Assessing the Differentiation Capacity of Human Lung Fibroblasts towards Endothelial Cells for Potential Clinical Exploitation

Abstract

The role of mesenchymal-to-endothelial transition in the angiogenic response is controversial. Toward this, the present study aimed to determine if fibroblasts contribute to angiogenesis. Endothelial differentiation of fibroblasts was induced by culturing MRC-5 cells (human fetal lung fibroblast cells) on top of Matrigel hydrogel or embedded inside the hydrogel. The formation of ca-pillary-like networks in response to angiogenic signals was observed. The tube formation occurs quickly and can be visualized us-ing a phase-contrast inverted microscope, and/or the cells can be treated with DAPI before the assay and tubes can be visualized through fluorescence or confocal microscopy. Furthermore, fibroblasts cultured in a higher concentration invaded the Matrigel hydrogel and formed stem-cell-like spheroids. These spheroids embedded in matrigel matrices of varying densities sprouted to form 3D connective-tissue networks. Collectively, our results highlight the endothelial differentiation capacity of human lung fibroblasts. The results obtained in this work may have an impact on the search for alternative cell sources for vascular tissue engineering and the overcome of obstacles to vascularization of autologous tissue-engineered constructs and the production of functional grafts for clinical use.