Transplantation and Homing of Mouse Embryonic Stem Cells Treated with Erythropoietin in Spleen and Liver of irradiated mice

Background: The present study was designed to evaluate the homing potential of mouse embryonic stem cells (ESC) treated with erythropoietin (EPO) in hematopoietic organs such as spleen and liver after transplantation using morphological and immuno-histochemical techniques. Methods: Day-four embryoid body (EB)-derived cells were dissociated and re-plated in medium in the presence and absence of EPO for three days. The EPO- and untreated differentiated cells were labeled with 5-bromo-2 deoxyuridine (BrdU) before transplantation and analyzed using flow cytometry and reverse transcription-PCR methods. BrdU-labeled cells were injected via the tail vein into irradiated adult mice in both groups. The spleen colony-forming unit assay (CFU-S) was performed 12 days after transplantation. Immuno-histochemistry was also carried out to trace transplanted cells. Results: The percentage of CD34 positive cells was 5.51 ± 1.06% in the EPO-treated group and 1.63 ± 0.225% in untreated group. The RT-PCR analysis showed that the EPO-treated cells expressed ε globin, βH1 globin, RUNX1 and EPO receptor genes, but the beta-major globin gene was not expressed. The number of colonies formed in the spleens of treated group (17.33 ± 4.726) was significantly different from the control group (6 ± 1). The population of BrdU positive cells in spleen of EPO-treated cell-transplanted group was higher than that of the control group. Also, BrdU positive cells were observed in the central vein of the liver sections of EPO-treated and control groups but were not observed in the liver parenchyma. There were not BrdU positive cells in the spleen and liver sections of the sham group. Conclusion: Our results confirm that ESC have the ability to home and form colonies in spleen after transplantation and EPO-treated EB-derived cells caused an increase in the number of colonies in spleen after CFU-S.