The effects of vasonatrin peptide on random pattern skin flap survival

Pharmacological and cell-based treatments to increase local skin flap viability in animal models

Local skin flaps are frequently employed for wound closure to address surgical, traumatic, congenital, or oncologic defects. (1) Despite their clinical utility, skin flaps may fail due to inadequate perfusion, ischemia/reperfusion injury (IRI), excessive cell death, and associated inflammatory response. (2) All of these factors contribute to skin flap necrosis in 10-15% of cases and represent a significant surgical challenge. (3, 4) Once flap necrosis occurs, it may require additional surgeries to remove the entire flap or repair the damage and secondary treatments for infection and disfiguration, which can be costly and painful. (5) In addition to employing appropriate surgical techniques and identifying healthy, well-vascularized tissue to mitigate the occurrence of these complications, there is growing interest in exploring cell-based and pharmacologic augmentation options. (6) These agents typically focus on preventing thrombosis and increasing vasodilation and angiogenesis while reducing inflammation and oxidative stress. Agents that modulate cell death pathways such as apoptosis and autophagy have also been investigated. (7) Implementation of drugs and cell lines with potentially beneficial properties have been proposed through various delivery techniques including systemic treatment, direct wound bed or flap injection, and topical application. This review summarizes pharmacologic- and cell-based interventions to augment skin flap viability in animal models, and discusses both translatability challenges facing these therapies and future directions in the field of skin flap augmentation.

The Effects of Vasonatrin Peptide on Fat Graft Viability: An Experimental Study

Vasonatrin peptide (VNP) is a synthetic peptide that possesses vasodilatory, natriuretic, and anti-inflammatory properties. The authors aimed to analyze the effects of VNP on fat graft survival. Twenty Sprague-Dawley rats are randomly divided into two groups of 10. Fat grafts are harvested from the right inguinal region. After preparation, fat grafts are placed to the interscapular region. The first group of rats were administered VNP after their fat injection, while the second group received tail-vein injections of an equal volume of sterile saline following their fat injection. Experiment and control groups are evaluated according to their level of degeneration of adipocytes, fat necrosis, vacuolization, cyst formation in adipocytes, fibrosis of the fat tissue, capillary density, and CD31 immunohistochemical staining. Degeneration, vacuolization, and cyst formation in adipocytes were lower in the experiment group. Increased capillary density in the experiment group was demonstrated by CD31 antibody staining and by counting capillary density under a microscope. The average percentage of change in weight of the fat grafts in the experiment group was lower than that in the control group. The results indicate that VNP has some beneficial effects on fat graft survival by multiple independent mechanisms that influence both local and systemic homeostasis.

Hyperoxygenated solution improves tissue viability in an avulsion injury flap model

BACKGROUND

Management of avulsion injuries remains a challenge due to necrosis. The aim of the present study is to create an experimental model reproducing an avulsion injury and investigate the effects of hyperoxygenated solution (HOS), a method of oxygen delivery that has been widely used in the therapy of ischaemia-hypoxia diseases, on avulsion injury flap survival in rats.

METHODS

Forty male rats were divided into four groups (n = 10 each). Dorsal random pattern flaps measuring 3 × 9 cm, including the panniculus carnosus, were elevated and run over by the skin avulsion model machine, and the flaps were then sutured into their original places. The sham+HOS and avulsion+HOS groups received intravenous HOS (20 ml/kg) each day for 7 days after the operation. The sham+saline and avulsion+saline groups received intravenous saline solution (20 ml/kg) each day for 7 days after the operation. Percutaneous O₂ pressure (TcpO₂) measurement_, serial examinations of skin flap blood perfusion, skin flap survival evaluation and histopathology were performed to assess the efficacy of HOS on avulsion injury.

RESULTS

Compared to the avulsion+saline groups, TcpO₂ was significantly higher in the avulsion+HOS groups at 15, 30 and 60 min after infusion (P < 0.05). The blood perfusion of flaps in the avulsion+HOS group was higher than in the avulsion+saline group (P < 0.05). The survival rate was higher in the avulsion+HOS group than in the avulsion+saline group (P < 0.05), and the histopathology assays supported the data.

CONCLUSION

We succeeded in developing an avulsion injury model and demonstrated that HOS could improve the survival of the avulsion injury flaps in rats by effectively increasing the local oxygen content and blood perfusion and ameliorating inflammatory damage.

Bioactive nanoparticle-based formulations increase survival area of perforator flaps in a rat model

BACKGROUND

Distal flap necrosis is a frequent complication of perforator flaps. Advances in nanotechnology offer exciting new therapeutic approaches. Anti-inflammatory and neo-angiogenic properties of certain metal oxides within the nanoparticles, including bioglass and ceria, may promote flap survival. Here, we explore the ability of various nanoparticle formulations to increase flap survival in a rat model.

MATERIALS AND METHODS

A 9 x 3 cm dorsal flap based on the posterior thigh perforator was raised in 32 Lewis rats. They were divided in 4 groups and treated with different nanoparticle suspensions: I-saline (control), II-Bioglass, III-Bioglass/ceria and IV-Zinc-doped strontium-substituted bioglass/ceria. On post-operative day 7, planimetry and laser Doppler analysis were performed to assess flap survival and various samples were collected to investigate angiogenesis, inflammation and toxicity.

RESULTS

All nanoparticle-treated groups showed a larger flap survival area as compared to the control group (69.9%), with groups IV (77,3%) and II (76%) achieving statistical significance. Blood flow measurements by laser Doppler analysis showed higher perfusion in the nanoparticle-treated flaps. Tissue analysis revealed higher number of blood vessels and increased VEGF expression in groups II and III. The cytokines CD31 and MCP-1 were decreased in groups II and IV.

CONCLUSIONS

Bioglass-based nanoparticles exert local anti-inflammatory and neo-angiogenic effects on the distal part of a perforator flap, increasing therefore its survival. Substitutions in the bioglass matrix and trace metal doping allow for further tuning of regenerative activity. These results showcase the potential utility of these nanoparticles in the clinical setting.

Salvianolic Acid B Promotes the Survival of Random-Pattern Skin Flaps in Rats by Inducing Autophagy

Random-pattern skin flap transplantation is frequently applied in plastic and reconstructive surgery. However, the distal part of the flap often suffers necrosis due to ischemia. In this study, the effects of salvianolic acid B (Sal B) on flap survival were evaluated, and the underlying mechanisms were investigated. Sal B improved the survival area, reduced tissue edema, and increased the number of microvessels in skin flaps after 7 days, whereas an autophagy inhibitor (3-methyladenine) reversed the Sal B-induced increase in flap viability. In addition, Sal B stimulated angiogenesis, inhibited apoptosis, reduced oxidative stress, and upregulated autophagy in areas of ischemia. Moreover, the effects of Sal B on angiogenesis, apoptosis, and oxidative stress were reversed by autophagy inhibition. Overall, our findings suggest that Sal B has pro-angiogenesis, anti-apoptosis, and anti-oxidative stress effects by stimulating autophagy, which enhances the survival of random-pattern skin flaps.

Effects of ozone gas on skin flaps viability in rats: an experimental study

BACKGROUND

The main purpose of this study was to assess the effects of ozone gas on the viability of flaps for reconstruction and to determine the optimum application method. The antioxidant, immunomodulatory, and reperfusion effects of ozone gas have been previously assessed, and successful results have been reported. However, only one study has investigated the effect of ozone gas on flap viability. In the present study, it was hypothesised that the antioxidant and reperfusion effects of ozone gas would enhance flap viability.

METHODS

Forty female Wistar rats were randomly divided into four groups of 10 rats each. A cranial-based, 3 × 11 cm modified McFarlane flap including the panniculus carnosus was raised from the dorsum of a rat and re-sutured to its own bed using 3/0 sharp propylene. Group 1 (n = 10): no pharmacological agent was used after the operation. Group 2 (n = 10): vegetable (olive) oil group; vegetable-oil-impregnated gauze was used as a dressing for 7 days. Group 3 (n = 10): Vegetable (olive) oil with ozone peroxide group; vegetable oil with ozone peroxide-impregnated gauze was used as a dressing for 7 days. Group 4 (n = 10): Hemo-ozone therapy group; hemo-ozone therapy was applied rectally once every day for 7 days. All rats were sacrificed at the end of week 1 and assessed macroscopically and histopathologically.

RESULTS

The proportion of substantive necrosis was less in group 4 than in the other three groups. Survival area ratios were better in groups 2 and 3 than in group 1; however, there was no significant difference between groups 2 and 3. No significant differences in the histopathological scores were observed among the groups.

CONCLUSION

Ozone gas enhanced flap viability. No differences in flap viability were observed between the vegetable oil and vegetable oil with ozone peroxide groups. The greatest benefit ratios were found in the hemo-ozone therapy group.

Prevention of unfavourable effects of cigarette smoke on flap viability using botulinum toxin in random pattern flaps: An experimental study

BACKGROUND

There are numerous clinical and experimental studies reporting unfavourable effects of cigarette smoke on skin flaps.

OBJECTIVE

To investigate whether unfavourable effects of cigarette smoke on flap survival could be reduced by botulinum toxin type A.

METHODS

Twenty-eight male Wistar albino rats (15 months of age, mean weight 210 g [range 180 g to 230 g]) were included. They were divided into four groups of seven animals each. The control group underwent the surgical procedure alone. Surgical procedure was performed after administration of botulinum toxin type A in the botulinum toxin (BTX) group, after exposure to cigarette smoke in the cigarette smoke (CS) group, and after BTX type A administration and exposure to CS in the CS+BTX (CS+BTX) group. Random pattern cutaneous flaps (3 cm × 9 cm) were elevated from the dorsum of all rats. Necrosis area was calculated in percentages (%) using Image J computer software. Tissue samples were examined histopathologically.

RESULTS

The mean necrotic area in the control group (26%) and in the BTX group (21%) were similar (P=0.497), whereas administration of BTX type A significantly decreased flap necrosis area in the rats exposed to CS (the mean necrosis areas were 41.5% in the CS group, and 26% in the CS+BTX group; P<0.001). Histopathological examination findings corroborated the unfavourable effects of CS and preventive effects of BTX type A.

CONCLUSION

Preoperative administration of BTX significantly enhanced flap viability in the rats exposed to CS. Further human studies are warranted to verify whether BTX type A could be used as an agent to reduce the risk of flap necrosis in patients who smoke.

Prevention of unfavourable effects of cigarette smoke on flap viability using botulinum toxin in random pattern flaps: An experimental study

Background

There are numerous clinical and experimental studies reporting unfavourable effects of cigarette smoke on skin flaps.

Objective

To investigate whether unfavourable effects of cigarette smoke on flap survival could be reduced by botulinum toxin type A.

Methods

Twenty-eight male Wistar albino rats (15 months of age, mean weight 210 g [range 180 g to 230 g]) were included. They were divided into four groups of seven animals each. The control group underwent the surgical procedure alone. Surgical procedure was performed after administration of botulinum toxin type A in the botulinum toxin (BTX) group, after exposure to cigarette smoke in the cigarette smoke (CS) group, and after BTX type A administration and exposure to CS in the CS+BTX (CS+BTX) group. Random pattern cutaneous flaps (3 cm × 9 cm) were elevated from the dorsum of all rats. Necrosis area was calculated in percentages (%) using Image J computer software. Tissue samples were examined histopathologically.

Results

The mean necrotic area in the control group (26%) and in the BTX group (21%) were similar (P=0.497), whereas administration of BTX type A significantly decreased flap necrosis area in the rats exposed to CS (the mean necrosis areas were 41.5% in the CS group, and 26% in the CS+BTX group; P<0.001). Histopathological examination findings corroborated the unfavourable effects of CS and preventive effects of BTX type A.

Conclusion

Preoperative administration of BTX significantly enhanced flap viability in the rats exposed to CS. Further human studies are warranted to verify whether BTX type A could be used as an agent to reduce the risk of flap necrosis in patients who smoke.