Role of vascular endothelial growth factor in inducing production of angiopoetin-1 - in vivo study in Fisher rats.

The aim of the study was to investigate how an intramuscular injection of plasmids with genes coding various pro-angiogenic factors: angiopoetin-1 (ANGPT1), vascular endothelial growth factor (VEGF165) and hepatic growth factor (HGF), influences the production of ANGPT1. 40 Healthy Fisher rats received i.m. injections containing plasmids encoding pro-angiogenic genes in thigh muscles. They were divided into four equal groups. The first group received the plANGPT1 plasmid and the second group- the pIRES/ANGPT1/VEGF165 bicistronic plasmid. The pIRES/VEGF165/HGF bicistronic plasmid was administered to the third group and an empty plasmid (control group) to the fourth group. The animals were euthanized after 12 weeks. In each group, the number of vessels stained with the anti-ANGPT1 antibody was assessed under an optical microscope. The anti-ANGPT1 antibodies stained the vessels in all the groups. There were on average 14.1 ±2.3 vessels in the the plANGPT1 group, 32.5 ±10.5 in the pl/RESANGPT1/VEGF group and 30.8 ±13.3 in the plRES/HGV/VEGF group. There were on average 7.3 ±2.3 stained vessels (p < 0.0001) in the control group . The VEGF plays a role in the induction of the production of ANGPT1. The administration of plasmids only encoding ANGPT1 does not induce its production.

The Formation of Blood Vessel After the Administration of the Plasmid Encoding Ang-1 Gene in Fischer Rats.

BACKGROUND: Chronic limb ischemia is a serious clinical problem. Patients who do not qualify for standard treatment may benefit from novel gene therapies. OBJECTIVES: This study evaluated angiogenesis following intramuscular injections of angiogenic plasmid Ang-1 in Fisher rats. MATERIAL AND METHODS: Twenty rats had plasmids injected intramuscularly in their hind limbs. The study group consisted of 10 animals which received the Ang-1 plasmid, while the control group consisted of 10 rats that received an empty plasmid. All the animals were euthanized after 12 weeks and tissue samples from the hind limb thigh muscles and internal organs were harvested for histological and immunohistochemical examinations. To assess the angiogenesis the number of vessels in the hind limb muscles visualized by the SMA and FVIII markers was counted for each animal in five separate microscopic fields. RESULTS: There were no pathological lesions or any signs of neoplastic angiogenesis in any of the 20 rats. The number of vessels visualized by the FVIII marker in the study group was two times higher than in the control group (median: 12, range: 7-25 vs. median: 6, range: 2-15; p < 0.0001). The median estimated that the number of vessels visualized by the SMA marker is 63% higher in the study group compared to the control group (median: 6.5, range: 1-12 vs. median: 4, range: 0-10; p = 0.0008). CONCLUSIONS: Intramuscular injections of Ang-1 plasmids induced angiogenesis in the rat hind limb muscles.