The H-shaped double-flap model was used in male Sprague-Dawley rats. After surgical procedures, the animals were randomized to receive intraperitoneal PDRN (8 mg/kg) or vehicle (NaCl 0.9 % ). Rats were euthanized 3, 5, and 10 days after skin injury, after the evaluation of skin perfusion by laser Doppler. The wounds underwent histologic analysis and were measured for VEGF messenger RNA and protein expression, hypoxia inducible factor-1-¦Á (HIF-1¦Á), and inducible nitric oxide synthase (iNOS) protein expression, and nitrite content.
Blood flow markedly increased in blood flow in ischemic flaps treated with PDRN, with a complete recovery starting from day 5 (ischemic flap + vehicle, 1.80 ¡À 0.25; ischemic flap + PDRN, 2.46 ¡À 0.25; P < .001). Administration of PDRN enhanced the expression of VEGF (ischemic flap + vehicle, 5.3 ¡À 0.6; ischemic flap + PDRN, 6.2 ¡À 0.5; P < .01) at day 5, and iNOS (ischemic flap + vehicle, 3.9 ¡À 0.6; ischemic flap + PDRN, 5.3 ¡À 1; P < .01), but reduced HIF-1¦Á expression (ischemic flap + vehicle, 7 ¡À 1.1; ischemic flap + PDRN, 4.8 ¡À 0.5; P < .05) at day 3. Histologically, the PDRN-treated group showed complete re-epithelialization and well-formed granulation tissue rich in fibroblasts.
These results suggest that PDRN restores blood flow and tissue architecture, probably by modulating HIF-1¦Á and VEGF expression, and may be an effective therapeutic approach in improving healing of ischemic skin flaps.