Résumé
Objective: To investigate the effect of natural hirudin on revascularization of ischemic skin flap in rats using Micro-CT and three-dimensional (3D) reconstruction. Methods: Thirty-two Sprague Dawley rats were prepared a ischemic skin flap (8.0 cm×1.8 cm) model on the back and randomly divided into hirudin group and control group (16 rats in each group). At immediate and within 3 days after operation, the rats were treated with hypodermic injection of natural hirudin 0.3 mL (including natural hirudin 6 ATU) every day in hirudin group and the equal amount of normal saline in control group. At 6 days after operation, the survival rate of skin flap was evaluated, histological changes were observed by HE staining, and the volemia, length of blood vessels, and number of blood vessels were analyzed with Micro-CT 3D reconstruction. Results: Both groups of rats survived to the end of the experiment without infection. Different degrees of necrosis occurred in the distal part of the skin flaps in both groups at 6 days after operation, but the flap survival rate of the hirudin group (72.11%±8.97%) was significantly higher than that of control group (58.94%±4.02%) ( t=3.280, P=0.008). Histological observation showed that the histological hierarchy of the hirudin group was clearer than that of the control group, with more microangiogenesis and less inflammatory response and inflammatory cell infiltration. Micro-CT 3D reconstruction showed that the flap vessels in the hirudin group were more and denser, and the volemia, length of blood vessels, and number of blood vessels were significantly higher than those in the control group ( P<0.05). Conclusion: Natural hirudin can reduce the inflammation of tissue, promote the regeneration and recanalization of blood vessels in ischemic skin flap, so as to improve the survival rate of the flap.
Résumé
Apoptosis is a physiologic or programmed cell death process which is controlled by genes and it is essential for the function and the appropriate development of multicellular organism. Apoptosis is also thought to be one of the main mechanisms of cell death in ischemic tissues. The effect of prostaglandin E1(PGE1) is proven to be useful in the recovery of ischemic changes by inducing vasodilation of peripheral vessels and platelet disaggregation. Prostaglandin is also known to suppress apoptosis in a serum deprived cell. The purpose of this study is to evaluate the effects of PGE1 on the apoptosis in the ischemic skin island flap. Thirty Sprague-Dawley rats were used. In control group(n=15), 3x5cm sized skin island flap based on the superficial epigastric vessel was elevated and its pedicle was occluded for 14 hours. After removing the vessel clamp, skin flap was reperfused for 5 hours and harvested. In experimental group(n=15), a ischemic skin island flap was also made as in the control group except the interarterial administration of the PGE1 right after elevation of the flap and after removing the clamp. H&E, TUNEL and immunohistochemical stains for p53 and bax proteins were performed. There were ischemic changes in gross and microscopic findings in both groups. Immunohistochemical staining for p53 protein shows many positive cells with nuclear staining in squamous epithelium of the control group, but sparse positive cells in the experimental group. Immunohistochemical stainings for bax protein shows many positive cells with cytoplasmic staining in squamous epithelium of the control group, but sparse positive cells in the experimental group. The apoptotic index was significantly lower in the experimental group(2.39+/-1.76(p=0.0001)) than in the control group(7.53+/-2.05). These data indicate that PGE1 suppresses the apoptosis in the ischemic skin island flap.