Fig. 7
NO and PGE2 are only partially involved in MSC-mediated macrophage polarization. MSCs were transfected with iNOS- or COX-2-specific siRNAs to reduce NO and PGE2 secretion and further stimulated with IFN-ɣ and IL-1ß. Transfected, activated MSCs (acMSCs+siRNA) were co-cultured with M0 macrophages under M1- (20 ng/ml IFN-gamma + 100 ng/ml LPS, a) and M2a- (20 ng/ml IL-4, b) polarizing culture conditions for 24 h. Preconditioned MSCs (acMSCs) served as controls. Gene expression of IL-6, TNF-α, M2a markers (Ym-1, FIZZ1/RELMα), M2b markers (SPHK1, LIGHT), and the M2c marker MertK in macrophages was analyzed by real-time PCR. Results are representative for six to eight independent experiments and are expressed as fold change vs. expression found in macrophages. *p < 0.05, **p < 0.01. FIZZ1/RELMα, found in inflammatory zone 1/resistin-like molecule alpha, IL interleukin, LIGHT lymphotoxin-like, exhibits inducible expression and competes with HSV glycoprotein D for herpes virus entry mediator, a receptor expressed by T lymphocytes, M macrophage, MertK tyrosine-protein kinase MER, MSCs mesenchymal stem cells, acMSCs activated, preconditioned mesenchymal stem cells, SPHK1, sphingosine kinase 1, TNF-α tumor necrosis factor alpha, Ym-1 chitinase-like protein