To discover avenues for curing diseases, studies on therapeutic approaches have been done extensively and have continued to increase at an accelerated pace. To this end, many areas of research have emerged, including one of the most fascinating and highly active areas currently, stem cell therapies. Due to the self-renewal property and differentiation ability of stem cells, it becomes a new hope in modern treatment. The first successful case of stem cell therapy in humans was reported in 1959. Bone marrow restorations were observed in leukemia patients who received total body irradiation. subsequently by intravenous injection of the bone marrow of their twins (Thomas et al, 1957). However, this effect was transient and subsequent attempts at bone marrow transplantation in patients and non-twin donors may eventually lead to patient death from graft-versus-host disease (Mathé et al, 1965). During that period, the safety of hematopoietic cell transplantation was not guaranteed due to limited knowledge on human histocompatibility and immunosuppression. However, the turning point came after the discovery of human leukocyte antigen (HLA) groups (Dausset, 1958; van Rood et al, 1958), HLA typing and compatibility tests were performed before transplantation. Furthermore, the improvement of the immunosuppressive protocol also contributes to making bone marrow transplantation increasingly successful (Donnall and Hutchinson, 1999). Although the success rate of hematopoietic stem cell therapy was high, patient mortality still occurred due to some factors. In addition to the previously mentioned graft-versus-host disease, infection contributes to the majority of patient deaths (Kernan et al, 1993). In allogeneic...... half of the article ...... there are some risk factors in the use of stem cells for therapeutic approaches, hematopoietic stem cell therapy by bone marrow transplant has already been shown to be safe if donor background and screening, cellular contamination, HLA matching and opportunistic or nosocomial infections during the immunocompromised period have been carefully monitored and controlled. However, other types of stem cell therapies, despite their good therapeutic efficacy, remain in the experimental phase and require more data to support and demonstrate safety in clinical trials. A greater understanding of stem cell biology is also needed to keep stem cells under control and avoid some of the complications they may cause. Therefore, to pave the way for the success of stem cell therapy, research to this extent is needed to pursue maximization of therapeutic efficiency with maximum safety in patients..