Following the discovery that bone marrow transplantation could be used to rescue irradiated mice, the identification and characterization of the haemopoietic stem cells has become essential in order to achieve new developments in stem cells expantion and transplantation (Scott&gordon, 1995)Bone marrow or peripheral blood stem cell transplantation is used in the treatment of cancer for two reasons. First, transplantation permits exploitation of the steep dose –response relationship seen in some tumors by allowing administration of doses of systemic chemotherapy and radiotherapy that without transplantation would cause unacceptably sever or lethal myelosuppression. Second, transplantation of allogeneic marrow confers an antitumor effect, separate from the effects of chemoradiotherapy (Anderson et al., 1993)Recently, the laboratory research reported the successful expansion of cells from the adult bone marrow that have the potential to differentiate into ectodermal (neuronal), mesodermal (vascular endothelium), and endodermal (liver) cell types in vitro. In vivo, these cells show similar plasticity and contribute to multiple tissues after transplantation (Jiang et al., 2002)Several recent reports have highlighted the broad developmental potential of bone marrow-derived stem cells and the term "stem cell plasticity" has been coined. Haematopoietic stem cells (HSCs) have been reported to produce not only all of the blood lineages, but also skeletal muscle, (Ferrari G et al., 1998) neurons, (Mezey E et al., 2000) cardiac muscle, (Orlic et al., 2001) pulmonary epithelium, (Krause DS et al., 2001) and liver epithelium. The transdifferentiation of bone marrow derived cells into hepatic cells was first described in the rat, (Petersen BE et al., 1999). Followed by reports for the mouse (Theise ND et al., 2000) and also the human (AlisonMR et al., 2001) they were able to demonstrate that bone marrow transplantation (BMT) could substitute for hepatocyte transplantation and correct the liver disease in this model (Lagasse E et al., 2000)It was furthermore demonstrated that prospectively isolated HSCs can transdifferentiate into hepatocytes and this suggested that the HSCs may indeed be plastic and be capable of producing both blood and hepatocytes (Wang X et al, 2003)