Previous studies report oxidative stress induced apoptosis and necrosis occur following myocardial infarction. Effects of conditioned medium (CM) prepared from mouse embryonic stem (ES) cells on H2O2 induced apoptosis and necrosis in different cells types is under investigation. Additionally, effects of CM from ES cells primed with TGF-b2 on stress-induced apoptosis and necrosis in H9c2 cells have not been determined. In this study, H20i induced apoptosis was confirmed by trypan blue staining, terminal deoxynucleotide transferase dUTP-mediated nick-end labeling (TUNEL), and apoptotic enzyme labeled immunosorhent assay (ELISA) whereas necrosis was determined by LDH assay. Next, we generated CM from ES cells primed with and without TGF-b2 and determined their effects on H2O2 induced apoptosis and necrosis in H9c2 cells. Apoptosis and necrosis was significantly (P < 0.05) reduced with ES-CM compared with cell culture control. Next, our data showed TGF-B2 primed ES-CM further reduced cell death compared with ES-CM, suggesting increased amounts of cytoprotective released factors from mouse ES cells following TGF-B2 treatment. Furthermore, the treatment of H9c2 cells with TGF-b2 alone did not significantly (P < 0.05) reduce apoptotic cell death. In conclusion, we suggest that factors released from ES cells with and without TGF-B2 treatment contain anti-apoptotic and anti-necrotic factors that inhibit H2O2 induced cell death. Further studies are needed to determine potential additional benefits of the · released factors from TGF-B2 primed ES cells.