FIG. 3. The sustained upregulation of the humoral factors in ischemic myocardium after cell transplantation is attributable to host cells.

To determine whether the upregulated cytokines after cell transplantation into infarcted myocardium were derived from injected donor cells or recipient host cells, human EPCs were transplanted into immunocompromised nude mice, and the levels of cytokines were measured by both human- and mouse-specific primers and probes for each cytokine, such as VEGF or FGF-2. The expression levels of cytokines from human EPCs (donor cells) were at their highest levels at day 1 and decreased to an undetectable range within 7 days. Most of the mouse (host)-specific cytokine levels continued to increase after day 1 and were maintained at higher than the baseline levels over a 14-day period (n=5 per each time point). Individual values were normalized to GAPDH and shown as fold difference from the values at day 1. VEGF-A, vascular endothelial growth factor-A; FGF-2, fibroblast growth factor-2; Ang-1, angiopoietin-1; Ang-2, angiopoietin-2; PlGF; placental growth factor; HGF, hepatocyte growth factor; IGF-1, insulin-like growth factor-1; PDGF-B, platelet-derived growth factor, B polypeptide; SDF-1, stromal cell-derived factor-1. Originally published in Journal of Experimental Medicine (DOI: 10.1084/JEM20070166; ref. 15). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article at www.liebertonline.com/ars).