Abstract

 Background and Objectives

 Stem cells are defined with two main characteristics which are self renewal potential and pluripotency. It is of great importance to study expression of self renewal genes in different stem cells, because self renewal regulatory mechanisms may vary among different kinds of stem cell. Human umbilical cord stem cells have recently gained so much attention, because their use in cell therapy methods has several advantages. The main objective of the present study was to evaluate the expression of Oct-4, Sox-2, Nanog, Nucleostemin, Bmi-1 and Sox-9 self renewal genes in human umbilical cord vein mesenchymal stem cells.

 Materials and Methods

 In this experimental study, umbilical cords were obtained in sterile condition and carried to the laboratory in HBSS buffer. Mesenchymal stem cells were harvested by collagenase treatment and cultured by means of their adhesiveness to plastic surfaces in DMEM medium supplemented with 15% FBS. To confirm the mesenchymal identity of these cells, expression of some surface markers including CD105, CD106, CD54, CD45, HLA-DR, CD166, and CD34 was analysed by means of flowcytometery. Finally, expression of self renewal genes was evaluated by RT-PCR and immunocytochemistry techniques.

 Results

 Flowcytometry analysis of UBMCs revealed that the cells are positive for CD105 (98%) and negative for CD34 (0%), CD54 (1%), CD45 (0%), CD106 (0%), CD166 (0%), and HLA-DR (0%). Our results also revealed Oct-4, Nanog, Nucleostemin, Bmi-1 and Sox-9 expression in human umbilical cord vein mesenchymal stem cells, but not Sox-2 self renewal gene expression.

 Conclusions

 The results showed that the mechanism which is known today for Oct-4, Nanog and Sox-2 function is not the only possible mechanism in which these three genes can play role to regulate self renewal potential of stem cells. Obtained results can offer that a combination of regulatory mechanisms which regulate self renewal of adult and embryonic stem cells, may be responsible to regulate self renewal of stem cells.

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 Key words : Mesenchymal stem cells, Umbilical cord, PCR, Immunocytochemistry