Conversion of vascular endothelial cells into multipotent stem-like cells.

Area of Science:

• Cell Biology
• Regenerative Medicine
• Developmental Biology

Background:

• Mesenchymal stem cells (MSCs) have varied clinical applications due to inconsistent isolation methods and tissue sources.
• The multipotent differentiation capacity of MSCs remains a subject of debate.
• Understanding alternative stem cell origins is crucial for advancing regenerative medicine.

Purpose of the Study:

• To investigate the potential of vascular endothelial cells to differentiate into multipotent stem-like cells.
• To elucidate the role of activin-like kinase-2 (ALK2) in endothelial cell transformation.
• To explore the implications of this cellular plasticity for tissue engineering.

Main Methods:

• Utilized fibrodysplasia ossificans progressiva (FOP) patient lesions and transgenic mice with constitutively active ALK2.
• Performed lineage tracing using Tie2-Cre constructs in mice.
• Induced endothelial-to-mesenchymal transition (EnMT) by expressing active ALK2 or treating with TGF-β2/BMP4 ligands.

Main Results:

• Chondrocytes and osteoblasts in FOP lesions and ALK2-mutant mice expressed endothelial markers.
• Lineage tracing indicated an endothelial origin for cells in heterotopic ossification.
• Active ALK2 expression or specific ligand treatment induced EnMT and a stem-like phenotype in endothelial cells.
• These induced stem-like cells differentiated into osteoblasts, chondrocytes, and adipocytes.

Conclusions:

• Vascular endothelial cells can be converted into multipotent stem-like cells through an ALK2-dependent mechanism.
• This endothelial-to-stem-like cell conversion offers a novel avenue for tissue engineering.
• The findings challenge traditional stem cell concepts and open new therapeutic possibilities.