Objective: the aim of the study is to investigate the histological, biochemical and the immunohistochemical effects of both intravenous injection of cord blood dervied-stem cell CD34+, and their mobilization from bone marrow by subcutaneous injection of granulocyte colony-stimulating factor (GC-SF) after induction of acute myocardial ischemia.
Materials and Methods: the study included 4 groups of albino rats (8 rats each). The first was reserved as control, while the other 3 groups were subjected to induction of acute myocardial ischemia. The second one was considered as ischemic group without any treatment. The third received intravenous cord blood injection after induction of ischemia. The myocardium were dissected and stained with H & E and Masson trichrome (for histological studies), and immunoperoxidase (for immunohistochemical studies). 
Results: there was a decrease in the extent of myocarial fibrosis in groups treated with GC-SF, and a significant decrease in those treated with cord blood stem cells. A Parallel to the significant increase in the number of positively stained vascular endothelial cells in rats treated with cord blood stem cells was detected. 
Conclusion: cord blood derived-stem cell CD34+ and GC-SF depressed myocaridal ischemia; however, further studies are needed to know the mechanism of regeneration of teh myocardium after its damage.