Mutant hypoxiainducible factor 1α modified bone marrow mesenchymal stem cells ameliorate cerebral ischemia

Hypoxiainducible factor 1α (HIF1α) plays stimulatory roles in revascularization in the ischemic area of cerebral ischemia. However, the hydroxylation of proline at 564 and asparagine at 803 in the HIF1α coding sequence facilitated the degradation of HIF1α and inhibited the transcription activity of the HIF1α promoter under normoxic conditions and confined the proangiogenic efficacy of HIF1α. In the present study, the HIF1α mutant containing P564A and N803A was constructed by sitedirected mutagenesis. Rat bone marrow mesenchymal stem cells (BMSCs) were infected with adenoviral particles containing HIF1α mutant at multiplicity of infection of 150. The HIF1α mRNA and protein levels under hypoxia and normoxic conditions were compared using reverse transcriptionpolymerase chain reaction and western blot analysis. To explore the therapeutic effect of mutant HIF1α on the cerebral ischemia, BMSCs overexpressing mutant HIF1α were transplanted in the rat middle cerebral artery occlusion model (MCAO). The motor function and cerebral infarct size were evaluated using modified neurological severity score and triphenyltetrazolium chloride (TTC) staining within four weeks after MCAO. Vascular endothelial growth factor (VEGF) protein expression was detected by western blot analysis. Microvessel density and angiogenesis were detected by immunohistochemistry to evaluate the recovery of the brain ischemia. The HIF1α mutant containing P564A and N803A could be expressed under normoxic conditions. Transplantation of BMSCs stably expressing mutant HIF1α significantly improved motor function, reduced cerebral infarction and increased VEGF protein expression revascularization at days 7, 14 and 28 (p<0.05). Therefore, the HIF1α mutant containing P564A and N803A may be a potential target for the treatment of the cerebral ischemia.