Human embryonic stem cells secrete macrophage migration inhibitory factor: A novel finding

Area of Science:

• Cell Biology
• Stem Cell Biology
• Immunology

Background:

• Macrophage migration inhibitory factor (MIF) is a crucial cytokine involved in various biological processes.
• Limited information exists regarding MIF expression and function in human embryonic stem cells (ESCs).

Purpose of the Study:

• To investigate the expression of MIF and its receptors in human ESCs.
• To determine the functional role of MIF in human ESC proliferation and survival.

Main Methods:

• Immunofluorescence assay, RT-qPCR, and western blotting were used to detect MIF and its receptors (CD74, CD44, CXCR2, CXCR4, CXCR7).
• Enzyme-linked immunosorbent assay measured autocrine MIF levels.
• Co-immunoprecipitation and confocal microscopy examined MIF-receptor interactions.
• Proliferation and survival assays were conducted using exogenous MIF, CXCL12, and ISO-1.

Main Results:

• MIF was highly expressed in H1 and H9 human ESCs, localized in the cytoplasm, cell membrane, and culture medium.
• Autosecreted MIF concentration was significantly higher (22 ng/mL) than in normal human serum.
• Human ESCs predominantly expressed CXCR2 and CXCR7, with CXCR7 identified as the primary interacting receptor for MIF.
• No evidence supported MIF's role in promoting human ESC proliferation or survival.

Conclusions:

• MIF is highly expressed in human ESCs and associated receptors, suggesting a predominantly autocrine signaling mechanism.
• CXCR7 is the main receptor mediating MIF function in human ESCs.
• MIF does not appear to support the proliferation and survival of human ESCs.