Objective To explore the effects of natural hirudin on the survival of dorsal random flap after early pedicle division in rats. Methods Thirty-eight adult Wistar rats, male or female, weighing 220-280 g, were selected and randomly divided into natural hirudin group (experimental group, n=19) and normal saline group (control group, n=19). The dorsal random flap of 9 cm × 3 cm in size was prepared on the back of the rats. Six symmetrical injection points were selected at 2, 4, and 8 cm from the pedicle, 0.5 mL (3 ATU) natural hirudin and equivalent normal saline were injected in experimental group and control group respectively every day to the end of the experiment. After 4 days, the pedicles were cut. The flap was observed, and the ratio of flap survival area was measured at 7 days after pedicle division. At immediately after flap preparation, at 1 day before pedicle division, and at 3 and 7 days after pedicle division, the specimens were harvested for histological staining, immunohistochemical staining, microvessel density (MVD) measurement, and detection of vascular endothelial growth factor (VEGF) mRNA expression by fluorescent quantitative RT-PCR. Results All rats of 2 groups survived to the completion of the experiment. After pedicle division, the flap necrosis area of experimental group was smaller than that of control group; at 7 days, the ratio of flap survival area in experimental group was 85.366% ± 2.872%, and was significantly higher than that in control group (75.252% ± 3.455%) (t=7.117, P=0.000). Histological staining showed that no significant difference was found in the number of capillaries between 2 groups at immediately after flap preparation; at 1 day before pedicle division and at 3 and 7 days after pedicle division, the capillary number of experimental group was significantly more than that of control group. Immunohistochemical staining showed that CD34 positive cells were observed in 2 groups; MVD of experimental group was significantly higher than that of control group at 1 day before pedicle division, and at 3 and 7 days after pedicle division (P lt; 0.05). At 7 days after pedicle division, the VEGF mRNA expression was 7.122 ± 0.503 in experimental group, and was 5.655 ± 1.174 in control group, showing significant difference (t=3.633, P=0.003). Conclusion Natural hirudin can promote the formation of new blood vessels, improve the blood supply of the flap, and increase the survival of random flap after early pedicle division by increasing VEGF expression.
Objective To explore the effect of natural hirudin on proliferation of human microvascular endothelial cells (HMVECs) and its preliminary mechanism of promoting angiogenesis. Methods Three-dimensional culture models of HMVECs were established in vitro and observed by inverted phase contrast microscopy after 24 hours of culturing. Then, the three-dimensional culture models of HMVECs were treated with different concentrations (1, 4, and 7 ATU/mL) of the natural hirudin, respectively, and Dulbecco’s modified Eagle’s medium containing 10% fetal bovine serum as control. The cell proliferations of 4 groups were detected by cell counting kit 8 (CCK-8) method at 24, 48, and 72 hours; the angiogenesis of 4 groups were observed by tube formation assay at 24 hours; the expressions of vascular endothelial growth factor (VEGF) and Notch1 of HMVECs in 4 groups were observed by immunofluorescence staining at 24 hours. Results The observation of cells in three-dimensional culture models showed that HMVECs attached to Matrigel well, and the cells formed tube structure completely after 24 hours. The results of CCK-8 test showed that the absorbance (A) value of 1 and 4 ATU/mL groups were higher than that of control group at each time point (P<0.05), andA value of 4 ATU/mL group was the highest. The A value of 7 ATU/mL group was significantly lower than those of 1 and 4 ATU/mL groups and control group (P<0.05). The tube formation assay showed that the tube structure was more in 1 and 4 ATU/mL groups than in 7 ATU/mL group and control group, and in 4 ATU/mL group than in 1 ATU/mL group, showing significant differences (P<0.05). There was no significant difference between 7 ATU/mL group and control group (P>0.05). The results of immunofluorescence staining showed that compared with control group, the Notch1 expression was higher in 1 and 4 ATU/mL groups and lower in 7 ATU/mL group; and there was significant difference between 4 and 7 ATU/mL groups and control group (P<0.05). The VEGF expression was higher in 1, 4, and 7 ATU/mL groups than in control group, in 4 ATU/mL group than in 1 and 7 ATU/mL groups, showing significant differences (P<0.05). Conclusion Natural hirudin can promote angiogenesis at low and medium concentrations, but suppress angiogenesis at high concentrations. Its mechanism may be related to the VEGF-Notch signal pathway.
ObjectiveTo investigate the effect of natural hirudin on revascularization of ischemic skin flap in rats using Micro-CT and three-dimensional (3D) reconstruction.MethodsThirty-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.ResultsBoth 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).ConclusionNatural 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.
ObjectiveTo investigate the effect of natural hirudin combined with hyperbaric oxygen therapy on the survival of transplanted random-pattern skin flap in rats.MethodsA random-pattern skin flap in size of 10.0 cm×2.5 cm was elevated on the dorsum of 72 Sprague Dawley rats. Then the 72 rats were randomly divided into 4 groups (n=18) according to the therapy method. At immediate and within 4 days after operation, the rats were treated with normal saline injection in control group, normal saline injection combined with hyperbaric oxygen treatment in hyperbaric oxygen group, the natural hirudin injection in natural hirudin group, and the natural hirudin injection combined with hyperbaric oxygen treatment in combined group. The flap survival was observed after operation, and survival rate was evaluated at 6 days after operation. The skin samples were collected for histological analysis, microvessel density (MVD) measurement, and evaluation of tumor necrosis factor α (TNF-α) expression level by the immunohistochemical staining at 2 and 4 days after operation.ResultsPartial necrosis occurred in each group after operation, and the flap in combined group had the best survival. The survival rate of flap was significantly higher in hyperbaric oxygen group, natural hirudin group, and combined group than that in control group, and in combined group than in hyperbaric oxygen group and natural hirudin group (P<0.05). There was no significant difference between hyperbaric oxygen group and natural hirudin group (P>0.05). At 2 days, more microvascular structure was observed in hyperbaric oxygen group, natural hirudin group, and combined group in comparison with control group; while plenty of inflammatory cells infiltration in all groups. At 4 days, the hyperbaric oxygen group, natural hirudin group, and the combined group still showed more angiogenesis. Meanwhile, there was still infiltration of inflammatory cells in control group, inflammatory cells in the other groups were significantly reduced when compared with at 2 days. At 2 days, the MVD was significantly higher in hyperbaric oxygen group, natural hirudin group, and combined group than that in control group (P<0.05); the expression of TNF-α was significantly lower in hyperbaric oxygen group, natural hirudin group, and combined group than that in control group (P<0.05). There was no significant difference in above indexes between hyperbaric oxygen group, natural hirudin group, and combined group (P>0.05). At 4 days, the MVD was significantly higher in hyperbaric oxygen group, natural hirudin group, and combined group than that in control group, in natural hirudin group and combined group than in hyperbaric oxygen group (P<0.05). The expression of TNF-α was significantly lower in hyperbaric oxygen group, natural hirudin group, and combined group than that in control group, in combined group than in natural hirudin group and hyperbaric oxygen group (P<0.05).ConclusionHyperbaric oxygen and natural hirudin therapy after random-pattern skin flap transplantation can improve the survival of flaps. Moreover, combined therapy is seen to exhibit significant synergistic effect. This effect maybe related to promotion of angiogenesis and the reduction of inflammation response.