Abstract 16270: Wnt16 Enhances Cardiogenesis of Resident-Cardiac Stem Cells and Repair of Ischemic Hearts
Wnt proteins regulate morphogenesis and activate cardiogenesis in embryonic and bone marrow-derived stem cells via canonical or non-canonical signaling pathways. Our previous study showed involvement of Wnt in regulating cardiogenic differentiation of CD117+ LIN- RCSC. RCSC cultured with Wnt16 displayed enhanced expression of cardiac transcription factors (GATA4 and Nkx2.5), and structural molecules (cTnT, αMHC, α-s-actinin). This study aimed to (i) decipher Wnt16 signaling involvement in cardiogenesis, (ii) evaluate Wnt16’s cardioprotective potential, and (iii) determine the reparative role of Wnt16-RCSC in ischemic heart. CD117+/LIN- RCSC were isolated by magnetic bead separation, and analyzed by flow-cytometry (FC). Inhibition assays (siRNA-Dvl2/U73122 inhibitor) analyzed Wnt16 activated pathways. Wnt16-GFP-RCSC transfection efficiency was confirmed by immuno-blot (I-B) and -fluorescence. Rat hearts underwent ischemia (30min) in 3 groups (n=5) (control/media, RCSC/untreated and Wnt16-GFP-RCSC) before injection of ∼1x106 cells into infarct-border zone, 2 mm apart. Heart tissue was harvested at 48h and 4w for histology and assay of cardio-protective/pro-apoptotic factors and cytokine response. RCSC analyzed via FC showed 99.73 ± 0.3% as CD117+. I-B of Wnt16 cultured RCSC showed elevated expression of GATA4, 3.2-fold; Nkx2.5, 2.8-fold; cTnT, 1.3-fold; αMHC, 2.1-fold; and α-s-actinin, 3.4-fold). Wnt16-GFP-RCSC decreased infarct size at 48h (ischemic area 30.8±1.4%, infarct 17.9±1.9% of LV vs 50.8±2.7%, 37.9±3.9%, p<0.05). At 4w Sirius red LV fibrotic area was 20±1.35% (Wnt16-GFP-RCSC), 35±1.8% (untreated RCSC) and 52±2.1% (control/media) (p<0.05). Cytokines - interleukin (IL) and TNF families showed decreased activity. Pro-apoptotic Bcl-2 and Bax, angiogenic VEGF and Flk-1, and cardio-protective phos-GSK3β, NF-κβ and MET were significantly up-regulated. Wnt16 can drive cardiogenesis in resident-cardiac stem cells by signaling through both canonical and non-canonical pathways. Reparative effects of RCSC in ischemic rat heart are enhanced through Wnt16 by increasing angiogenic, pro-apoptotic and cardio-protective factors, while having favorable effects on cytokine activity.
- © 2012 by American Heart Association, Inc.