Mehdi Azad - ۱Hematology Department, School of Medical Sciences, Tarbiat Modares University, Tehran, Iran
Saeid Kaviani - ۱Hematology Department, School of Medical Sciences, Tarbiat Modares University, Tehran, Iran
Mehrdad Noruzinia - ۱Hematology Department, School of Medical Sciences, Tarbiat Modares University, Tehran, Iran
Yousef Mortazavi - Hematology Department, Zanjan Medical Sciences University, Zanjan, Iran
Naser Mobarra - Department of Clinical Biochemistry, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. ۷Students’ Scientific Research Center, Tehran University of Medical Sciences, Tehran, Iran
Shaban Alizadeh - ۴Department of Hematology, Allied Medical School, Tehran University of Medical Sciences, Tehran, Iran
Mohammad Shahjahani - ۱Hematology Department, School of Medical Sciences, Tarbiat Modares University, Tehran, Iran
Fatemeh Skandari - ۱Hematology Department, School of Medical Sciences, Tarbiat Modares University, Tehran, Iran
Mohammad Hosein Ahmadi - Iranian Blood Transfusion Organizations, Medical Departmen
Amir Atashi - ۱Hematology Department, School of Medical Sciences, Tarbiat Modares University, Tehran, Iran
Saeid Abroun - ۱Hematology Department, School of Medical Sciences, Tarbiat Modares University, Tehran, Iran
Zahra Zonoubi - ۶Department of Obstetrics and Gynecology, Mahdiyeh Hospital, Shahid Beheshti University,Tehran, Iran

  Objective(s): Stem cell differentiation into different cell lineages depends upon several factors, cell cycle control elements and intracellular signaling elements, including P۱۵INK۴b and P۱۶INK۴a genes. Epigenetics may be regarded as a control mechanism which is affected by these factors with respect to their promoter structure.   Materials and Methods: The CD۳۴ + cord blood stem cells were purified, isolated and then expanded. The undifferentiated day genome was isolated from part of the cultured cells, and the seventh day differentiated genome was isolated from the other part after differentiation to erythroid lineage. The procedure was followed by a separate Real-Time PCR for the two genes using the obtained cDNA. The processed DNA of the former stages was used for MSP (Methylation Specific PCR) reaction. Finally, pre- and post differentiation results were compared. Results: After performing MSP for each gene, it became clear that P۱۵INK۴b gene has undergone methylation and expression in predifferentiation stage. In addition, its status has not been changed after differentiation. P۱۵INK۴b gene expression was reduced after the differentiation. The other gene, P۱۶INK۴a, showed no predifferentiation methylation. Itwas completely expressed methylated and underwent reduced expression after differentiation. Conclusion : Specific predifferentiation expression of P۱۵INK۴b and P۱۶INK۴a genes along with reduction in their expression after erythroid differentiation indicated animportant role for these two genes in biology of CD۳۴+ cells in primary stages and before differentiation. In addition, both genes are capable of epigenetic modifications due to the structure of their promoters.

Keywords: Gene expression Hematopoietic stem cells Methylation Tumor suppressor genes