[Gene transfers of kallikrein, bradykinin receptor B2 and a mutated B2 receptor stimulate neoangiogenesis in peripheral ischemia]. / La surexpression de la kallicréine tissulaire, du récepteur B2 de la bradykinine et d'une forme mutée du récepteur B2, stimule la néoangiogenèse dans un modèle d'ischémie périphérique.

In this work, we evaluated the angiogenic effect of the gene transfer of human tissue kallikrein (TK), bradykinin B2 receptor (B2R) and a mutated form (RB2m) in a rabbit peripheral model of ischaemia. We studied the effects of the transfection of each of these factors and the effects of their co-transfection. In New Zealand anesthetised rabbits we first induced an ischaemia of the left posterior leg by ligation-excision of the superficial femoral artery and its collaterals. Seven days later, we performed i.m. injections in the ischemic tight with transfection solutions containing either the control (pcDNA3 empty backbone) or the pcDNA3-TK, the pcDNA3-TK and the pcDNA3-B2R, the pcDNA3-TK and the pcDNA3-B2Rm. Twenty eight days later, the therapeutic effect was evaluated using ultrasonographic debitmetry of the common iliac artery, perfusion index (PI) = ischemic leg blood flow /non ischemic leg blood flow (%) and capillaries measurements i.e. capillary density: number of vessels/mm2 and the ratio of vessels/muscular fiber, in the adductors and gastrocnemian muscles. The PI was increased in each treated group vs control (32.61 +/- 5.2%), pcDNA3-TK: 59.72 +/- 2.33%; p = 0.001; pcDNA3-RB2: 55.25 +/- 2.29%; p = 0.008; pcDNA3-TK + pcDNA3-RB2: 84.77 +/- 3.15%; p < 0.001; pcDNA3-TK + pcDNA3-RB2m: 103.25 +/- 4.9%; p < 0.001. The capillary density and the vessel/muscular fiber ratio increased in a parallel with the hemodynamic in the ischemic adductors (pcDNA3-TK + pcDNA3-B2Rm > pcDNA3-TK + pcDNA3-RB2 > pcDNA3-TK = pcDNA3-B2R; p < 0.001). There was no angiogenic effect measurable neither in the non ischemic adductors (right) nor in the gastrocnemian muscles. In rabbit peripheral ischaemia, the cotransfection of TK and B2R increases the arterial flow in the treated leg and potentiates the neoangiogenesis. Cotransfection of the B2Rm cDNA enhanced the synergic effect of this therapeutic strategy.

[Angiogenesis and arteriogenesis are increased in the SHR at the pre-hypertensive stage]. / L'angiogenèse et l'artériogenèse sont accrues chez le SHR au stade pré-hypertensif.

OBJECTIVE: A microvascular rarefaction by angiogenic deficiency could promote the onset of hypertension in SHR, in young hypertensive patients and in normotensive descendants of hypertensive parents. We studied the angiogenic potency in prehypertensive SHR, in fibrin chambers implanted in rats, an in vivo model of angiogenesis. METHODS: Four-week pre-hypertensive SHR (n=9) and controls WKY (n=9) were implanted with fibrin gel chambers. The chamber is a cylinder (dia.: 13 mm; H: 5 mm) whose base is perforated with 10 holes of 0.8 mm. The chambers are filled with rat fibrin and implanted (n=4) into the rat dorsal subcutaneous space. After 14 days, vasculo-conjunctive buds have invaded the fibrin gel through the holes and the chambers are removed, fixed and coloured. The intact vascular buds were studied using optical microscopy. The number of vessels counted in central field corresponds to the vascular pedicle, the average number of vessels counted in 3 peripheral fields, represents the vascular branching. The number of arterialised vessels including at least 2 layers of SMC was counted in the central field of each bud. RESULTS: Both rat strains remained normotensive all along the experiment. In SHR fibrin chambers, the number of peripheral vessels (20 +/- 2.6 vs 9.5 +/- 3; p<0.0001) and the number of central arterialized vessels (7.5 +/- 2 vs 2.1 +/- 1.3; p<0.0001) was significantly higher compared to WKY. CONCLUSION: Angiogenesis and arteriogenesis are increased in pre-hypertensive SHR compared to WKY. These results plead against a microvascular rarefaction hypothesis in these genetically hypertensive rats.