A small molecule-based strategy for endothelial differentiation and three-dimensional morphogenesis from human...

Area of Science:

• Stem Cell Biology
• Developmental Biology
• Biochemistry

Background:

• Human embryonic stem cells (hESCs) are crucial for studying early human development.
• Self-organizing organoid models offer valuable in vitro platforms for mimicking in vivo developmental events.
• Understanding self-organization processes in hESCs is key to regenerative medicine and developmental studies.

Purpose of the Study:

• To identify novel small molecules that induce self-organization in hESCs.
• To characterize the resulting three-dimensional structures and their cellular identity.
• To establish a new in vitro model for studying endothelial progenitor cell formation.

Main Methods:

• Chemical screening of small molecules on 2D hESC cultures.
• Induction of self-organization in the absence of growth factors.
• Gene expression analysis, functional assays, and cell surface marker analysis (VE-cadherin, CD31, CD34, KDR, CD43).
• Molecular labeling (DiI-Ac-LDL) and morphological examination (VEGFR3).

Main Results:

• Two novel small molecules, BIR1 and BIR2, were identified.
• These molecules robustly induced the self-organization of balloon-shaped 3D structures from hESCs.
• The structures exhibited endothelial identity, with a putative endothelial progenitor population (VE-cadherin(+)CD31(+)CD34(+)KDR(+)CD43(-)).
• Intermediate structures, including multi-cellular modules and VEGFR3(+) sprouting structures, were observed.

Conclusions:

• BIR1 and BIR2 are potent inducers of hESC self-organization into endothelial structures.
• This novel balloon-shaped structure serves as a valuable in vitro model for studying early endothelial development.
• The findings provide new tools for investigating self-organization and endothelial progenitor cell biology.