A nucleic acid or transgene comprising a modified VEGF 3′-untranslated region (3′-UTR) polynucleotide sequence and a polynucleotide sequence encoding a Vascular Endothelial Growth Factor (VEGF). When transformed into a host cell, the nucleic acid or transgene exhibits a high stability and provides prolonged and reliable expression of VEGF. A method for extending the lifetime of transgene mRNA encoding VEGF in a mammalian host cell. A method for treating a subject in need of increased or modified expression of VEGF using this nucleic acid or transgene.