STAT3 mediates bone marrow mesenchymal stem cell VEGF production

Area of Science:

• Stem cell biology
• Molecular mechanisms of cell signaling
• Tissue repair and regeneration

Background:

• Mesenchymal stem cells (MSCs) show promise in tissue protection, but their underlying mechanisms are not fully understood.
• Vascular Endothelial Growth Factor (VEGF) is a key factor released by MSCs that may mediate tissue protection.
• Investigating the signaling pathways involved in MSC-mediated VEGF release is crucial for therapeutic applications.

Purpose of the Study:

• To elucidate the roles of STAT3 and p38 MAPK in mediating VEGF release from MSCs under basal and stress conditions (hypoxia, TNF).
• To test the hypothesis that stress activates MSCs to release VEGF via STAT3 and p38 MAPK dependent pathways.

Main Methods:

• Utilized wild-type (WT) and STAT3 knockout (STAT3KO) mouse MSCs.
• Analyzed VEGF release in MSC conditioned media under normoxia, hypoxia, and TNF stimulation.
• Investigated the effects of p38 MAPK inhibition on VEGF production.
• Assessed STAT3 and p38 MAPK activation via Western blot analysis of cell lysates.

Main Results:

• MSCs constitutively release VEGF, associated with basal STAT3 activity; STAT3 deficiency reduces VEGF production.
• Hypoxia or TNF stimulation significantly increases MSC VEGF release, correlating with activated p38 MAPK and STAT3.
• p38 MAPK inhibition reduced hypoxia- or TNF-induced VEGF release in WT MSCs.
• STAT3 ablation abolished hypoxia-induced VEGF release; p38 MAPK inhibition blocked VEGF release in STAT3KO MSCs under stress.

Conclusions:

• STAT3 partially mediates basal VEGF production by MSCs.
• Both STAT3 and p38 MAPK are critical for enhanced MSC VEGF release under stress conditions (hypoxia, TNF).
• Understanding these pathways offers potential for enhancing MSC-based therapies for tissue protection.