Exp Mol Med.  2012 Nov;44(11):674-683.

Long-term and stable correction of uremic anemia by intramuscular injection of plasmids containing hypoxia-regulated system of erythropoietin expression

• Sun J
• Wang Y
• Yang J
• Du D
• Li Z
• Wei J
• Yang A

Abstract

Relative deficiency in production of glycoprotein hormone erythropoietin (Epo) is a major cause of renal anemia. This study planned to investigate whether the hypoxia-regulated system of Epo expression, constructed by fusing Epo gene to the chimeric phosphoglycerate kinase (PGK) hypoxia response elements (HRE) in combination with cytomegalovirus immediate-early (CMV IE) basal gene promoter and delivered by plasmid intramuscular injection, might provide a long-term physiologically regulated Epo secretion expression to correct the anemia in adenine-induced uremic rats. Plasmid vectors (pHRE-Epo) were synthesized by fusing human Epo cDNA to the HRE/CMV promoter. Hypoxia-inducible activity of this promoter was evaluated first in vitro and then in vivo in healthy and uremic rats (n = 30 per group). The vectors (pCMV-Epo) in which Epo expression was directed by a constitutive CMV gene promoter served as control. ANOVA and Student's t-test were used to analyze between-group differences. A high-level expression of Epo was induced by hypoxia in vitro and in vivo. Though both pHRE-Epo and pCMV-Epo corrected anemia, the hematocrit of the pCMV-Epo-treated rats exceeded the normal (P < 0.05), but that of the pHRE-Epo-treated rats didn't. Hypoxia-regulated system of Epo gene expression constructed by fusing Epo to the HRE/CMV promoter and delivered by plasmid intramuscular injection may provide a long-term and stable Epo expression and secretion in vivo to correct the anemia in adenine-induced uremic rats.

Keyword

anemia; erythropoietin; gene therapy; hypoxia response element; uremia

MeSH Terms

Anemia/blood/*therapy
Animals
Base Sequence
Blood Urea Nitrogen
Cell Hypoxia
Creatinine/blood
Erythropoietin/biosynthesis/*genetics/secretion
Gene Expression Regulation
Genes, Reporter
Genetic Therapy
HeLa Cells
Humans
Injections, Intramuscular
Kidney/pathology
Luciferases, Firefly/biosynthesis/genetics
Molecular Sequence Data
Plasmids/*genetics
Promoter Regions, Genetic
Rats
Rats, Sprague-Dawley
Recombinant Proteins/biosynthesis/genetics/secretion
Response Elements
Transcriptional Activation
Uremia/blood/*therapy