Mesenchymal Stem Cell as a Vector for Gene and Cell therapy Strategies

Stem cells are undifferentiated biological cells that able to maintain undifferentiated state through cell division and give rise to any mature cell type. They are almost divided into embryonic (ESC) and adult stem cells (ASC). ASCs have lineage restriction in compare to ESCs which they cannot differentiate into all 3 layers (ectoderm, mesoderm and endoderm) [1,2]. The most characterized ASC population in bone marrow is hematopoietic (HSC) and mesenchymal stem cells (MSC). HSC was transplanted in many blood related diseases like as leukemia and HIV infection [3-6]. In addition to bone marrow transplantation,MSCs have ability to specifically target tumor tissue and pathological condition such as organ fibrosis [7,8]. It is provided alternative therapeutic approaches -cell and/or gene therapies- by unique selfrenewal and multi lineage differentiation capability of stem cells [9- 11], like as MSCs. They originate from mesoderm and in addition to chondrocytes, osteocytes and adipocytes, they can differentiateinto ectodermic and  endodermic cells [12]. There are three criteria to detect which cells are MSCs: 1) they must be plastic- adherent 2) Expression of mature stromal cell marker like as CD105, CD73, CD90 and lack of CD45,  CD34, CD14, CD19 and HLA-DR molecules expression at their surfaces 3) in vitro differentiation into  osteoblasts, adipocytes and chondroblasts [13].