Embryonic stem cells inhibit expression of erythropoietin in the injured spinal cord.
Recent observations have demonstrated neuroprotective role of erythropoietin (Epo) and Epo receptor in the central nervous system. Here we examined Epo function in the murine spinal cord after transplantation of pluripotent mouse embryonic stem (ES) cells pre-differentiated towards neuronal type following spinal cord injury. Expression of Epo was measured at both mRNA and protein levels in the ES cells as well as in the spinal cords after 1 and 7 days. Our data demonstrated that expression of Epo mRNA, as well as its protein content, in ES cells was significantly decreased after differentiation procedure. In the spinal cords, analysis showed that Epo mRNA level was significantly decreased after 1 day of ES cell injections in comparison to media-injected control. Epo protein level detected by Western blot was diminished as well. Examination of Epo production in the injured spinal cords after media or ES cells injections by indirect immunofluorescence showed increased Epo-immunopositive staining after media injections 1 day after injection. In contrast, ES cell transplantation did not induce Epo expression. Seven days after ES cell injections, Epo-immunopositive cells' distribution in the ipsilateral side was not changed, while the intensity of immunostaining on the contralateral side was increased, approaching levels in control media-injected tissues. Our data let us to presume that previously described immediate positive effects of ES cells injected into the injured zone of spinal cord are not based on Epo, but on other factors or hormones, which should be elucidated further.
Department of Physiology, The Brody School of Medicine, East Carolina University School of Medicine, Brody Building, 600 Moye Boulevard, Greenville, NC 27834, USA. mglazova@hotmail.com
Margarita
M
Glazova
Sarah
S
Hollis
Elena S
ES
Pak
Alexander K
AK
Murashov
D000818:Animals; D002454:Cell Differentiation; D002478:Cells, Cultured; D004195:Disease Models, Animal; D053595:Embryonic Stem Cells / Q000502:physiology* / Q000637:transplantation*; D004921:Erythropoietin / Q000235:genetics / Q000378:metabolism*; D005434:Flow Cytometry; D005786:Gene Expression Regulation / Q000502:physiology*; D049452:Green Fluorescent Proteins / Q000235:genetics; D051379:Mice; D057126:Nuclear Receptor Subfamily 4, Group A, Member 2; D012333:RNA, Messenger; D013119:Spinal Cord Injuries / Q000378:metabolism* / Q000601:surgery*; D013997:Time Factors; D014162:Transfection / Q000379:methods
C539884:Nr4a2 protein, rat; D057126:Nuclear Receptor Subfamily 4, Group A, Member 2; D012333:RNA, Messenger; D004921:Erythropoietin; D049452:Green Fluorescent Proteins