Culture medium was used as a control for nonspecific binding. Immunoblotting analysis Immunoblotting was done according to our standard pro tocols, as described previously. The protein samples were e tracted, quantified, and separated on SDS PAGE gels and electro transferred to nitrocellulose membranes. Nitrocellulose membranes were blocked in 5% nonfat milk and incubated with primary antibodies for PARP, BA , Survivin, cleaved caspase 9, Bcl 2, Bcl L, p ERK, p AKT, p JNK and B Actin. The blots were then e posed to HRP conjugated secondary mouse or rabbit antibodies and analyzed by using enhanced chemiluminescence Western blotting detection system. Inoculation of PC 3 cells and hUCMSCs in mice Nu nu BALB c mice were purchased from the Shizuoka Laboratory Center and maintained under classic conditions.

PC 3 cells and hUCMSCs were harvested and washed with 0. 1 ml PBS. The cells gently were mi ed with equal amount of growth factor reduced Matrigel on ice. PC 3 cells were subcutaneously trans planted into the left flank of mice, and, 2 weeks later, hUCMSCs stained with PKH26 dye were transplanted into the right flank of mice. Eight weeks after PC 3 cell inoculation, Matrigel plugs were isolated from mice for H E, immunohistochemistry, and TUNEL assay. The immunofluorescence staining image for PKH26 dye stained hUCMSCs in PC 3 cell tumor section was visualized under an A io vision 4. 0 fluorescence microscope. This study was approved by and conducted in accordance with the policies set forth by the Animal Care and Use Committee of Kyung Hee University 11 005.

Terminal deo ynucleotidyltransferase dUTP nick end labeling assay DNA fragmentation was analyzed by using Dead End fluorometric TUNEL assay kit. The tissues were fi ed in 4% methanol free formal dehyde solution in PBS for 35 minutes at 4 C and treated with terminal deo yribonucleotidyltransferase en zyme buffer AV-951 containing fluorescein 12 dUTP for 1 hour at 37 C in the dark. The slides were mounted with mounting medium containing 4,6 diamidino 2 phenylindole and visualized under an A io vision 4. 0 fluorescence microscope. Statistical analysis Statistical analysis was performed by using Microsoft E cel analysis tools and SigmaPlot 2001 software. All data values are shown as means standard deviation. The statistical significance was analyzed by using the Student t test and analysis of variance.

P values of 0. 05 were considered statistically significant. Results Characterizations of MSCs isolated from umbilical cord tissues Regular morphology of isolated MSCs from umbilical cord was observed under phase contrast micros copy, and very rare SA B gal positive senescent cells were found in passages 0, 1, 3, and 5 of hUCMSCs by B galactosidase assay. As shown in Figure 1B, the normal proliferation rate of isolated MSCs was also confirmed. Taken together, early passages of hUCMSCs are appro priate to use in this study.