Fig. 7: β-Catenin promotes the long-term survival of engrafted PBMSCs in ischemic hearts via the Oct4-related antiapoptotic pathway.

PBMSCs were infected with a reporter retrovirus expressing EGFP before transplantation and were recognized as EGFP-positive cells. a Representative fluorescence microscopy images of tissue sections showing the retention of EGFP (green)-labeled PBMSCs at the injection site at 90 days after transplantation. Scale bar: 50 μm. b Heart tissues were immunostained for EGFP-PBMSCs (green) and the cardiomyocyte marker troponin T (red) to verify the retention of transplanted PBMSCs and were counterstained with DAPI to detect the nuclei. Overexpression of β-catenin/Oct4 markedly improved the initial retention of donor PBMSCs compared with that in vector control cells, whereas shβ-catenin or shOct4 decreased the retention of transplanted PBMSCs. Scale bar, 50 μm. c Representative phenotype of gated EGFP⁺ cells evaluated by FACS. d Representative double TUNEL (terminal deoxynucleotidyl transferase UTP nick-end labeling) staining for apoptotic PBMSCs in the infarcted tissues. EGFP⁺ cells are shown as green. The red fluorescence represents apoptotic cells. Merged images indicate the apoptosis of transplanted PBMSCs. Note that more EGFP-labeled PBMSCs were apoptotic in the infarcted hearts receiving shβ-catenin or shOct4, as revealed by the presence of cells costained with TUNEL staining (red) and EGFP (green); 4',6-diamidino-2-phenylindole (DAPI) was used as a nuclear marker. Scale bar, 50 μm. e Quantitative data showing the retention of EGFP⁺ PBMSCs in the ischemic hearts. f Quantitative analysis of the percentages of EGFP-positive cells (EGFP⁺) relative to the whole ventricular cell population in the ischemic hearts after 90 days of transplantation using FACS. g Quantification of the apoptosis of transplanted PBMSCs in the infarcted tissues using the TUNEL assay. All graphs show the means ± SEMs. p < 0.05: *vs. PBS injection, ^#vs. PBMSC therapy alone, ^Δvs. transplantation of PBMSCs transfected with oeβ-catenin, oeOct4-, or shβ-catenin plus oeOct4, ^†vs. transplantation of PBMSCs transfected with oeβ-catenin plus shOct4 or shβ-catenin alone (n = 5 per group). h Quantitative analysis of the mRNA expression of β-catenin, Oct4, Bcl2, Birc5 (encoding survivin), Bax, and Casp3 (caspase-3). i Representative immunoblots of these molecules. P < 0.05: *vs. PBS injection, ^#vs. PBMSC therapy alone, ^Δvs. transplantation of oeβ-catenin-treated MSCs, ^†vs. transplantation of PBMSCs transfected with oeβ-catenin plus shOct4, ^§vs. transplantation of PBMSCs transfected with shβ-catenin alone (n = 5 per group).