Secreted proteoglycans directly mediate human embryonic stem cell-basic fibroblast growth factor 2 interactions...

Area of Science:

• Stem Cell Biology
• Biochemistry
• Developmental Biology

Background:

• Human embryonic stem cells (hESCs) require specific culture conditions for maintaining pluripotency.
• Conditioned medium from mouse embryonic fibroblast (MEF) feeder cells supports undifferentiated hESC proliferation.

Purpose of the Study:

• To identify the key factors in MEF-conditioned medium (CM) responsible for human ES cell proliferation.
• To elucidate the mechanism by which these factors support hESC culture.

Main Methods:

• Purification of MEF-secreted heparan sulfate proteoglycans (HSPG) from CM using column chromatography.
• Analysis of HSPG species using immunoblotting and mass spectrometry-based proteomic analysis.
• Assessing the role of HSPG in stabilizing fibroblast growth factor 2 (FGF2) and mediating its binding to hESCs.

Main Results:

• MEF-secreted HSPG coordinate human ES cell proliferation.
• HSPG stabilize FGF2 in unconditioned medium and mediate its binding to hESC surface receptors.
• Removal of HSPG from CM significantly impairs hESC proliferation.
• Multiple HSPG species were identified in CM.

Conclusions:

• Heparan sulfate proteoglycans (HSPG) are essential signaling cofactors in MEF-CM based human ES cell culture.
• HSPG play a critical role in maintaining hESC proliferation and pluripotency by modulating FGF2 activity.