The adverse effect of selective cyclooxygenase-2 inhibitor on random skin flap survival in rats

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.

Do NSAIDs Really Interfere with Healing after Surgery?

Perioperative analgesia should be multimodal to improve pain relief, reduce opioid use and thereby adverse effects impairing recovery. Non-steroidal anti-inflammatory drugs (NSAIDs) are an important non-opioid component of this approach. However, besides potential other adverse effects, there has been a longstanding discussion on the potentially harmful effects of NSAIDs on healing after surgery and trauma. This review describes current knowledge of the effects of NSAIDs on healing of bones, cartilage, soft tissue, wounds, flaps and enteral anastomoses. Overall, animal data suggest some potentially harmful effects, but are contradictory in most areas studied. Human data are limited and of poor quality; in particular, there are only very few good randomized controlled trials (RCTs), but many cohort studies with potential for significant confounding factors influencing the results. The limited human data available are not precluding the use of NSAIDs postoperatively, in particular, short-term for less than 2 weeks. However, well-designed and large RCTs are required to permit definitive answers.

Effects of Asiaticoside Treatment on the Survival of Random Skin Flaps in Rats

Background: Asiaticoside (AS) is extracted from the traditional herbal medicine Centella asiatica, and has angiogenic, antioxidant, anti-inflammatory, and wound-healing effects. We investigated the effects of AS on skin flap survival. Methods: Dorsal McFarlane flaps were harvested from 36 rats and divided into two groups: an experimental group treated with 40 mg/kg AS administered orally once daily, and a control group administered normal saline in an identical manner. On day 2, superoxide dismutase (SOD) and malondialdehyde (MDA) levels, and production of the cytokines tumor necrosis factor-α and interleukin (IL)-6 were evaluated. On day 7, tissue slices were stained with hematoxylin and eosin. The expression of vascular endothelial growth factor (VEGF), IL-6, and IL-1β were immunohistochemically evaluated. Microcirculatory flow was measured using laser Doppler flowmetry. Flap angiography, using the lead oxide-gelatin injection technique, was performed with the aid of a soft X-ray machine. Results: The AS group exhibited greater mean flap survival area, improved microcirculatory flow, and higher expression levels of SOD and VEGF compared with the control group. However, MDA levels and the inflammatory response were significantly reduced. Conclusions: AS exhibits promise as a therapeutic option due to its effects on the viability and function of random skin flaps in rats.

Inhibition of autophagy after perforator flap surgery increases flap survival and angiogenesis

BACKGROUND

The survival ratio of multiterritory perforator flap is variable. Therefore, surviving mechanisms are increasingly explored to identify novel therapeutics. The condition of the choke zone is essential for perforator flap survival. In this study, we investigated autophagy in the choke zone after flap surgery.

MATERIALS AND METHODS

The flap model involved a perforator flap with three territories that was located on the right dorsal side of a rat. A total of 36 rats were divided into six groups, including the control, 0 d postoperative (PO), 1, 3, 5, and 7 d PO groups. In addition, 72 rats were divided into three groups, including a control group, a 3-methyladenine (3-MA) group, and a rapamycin group. Skin tissue of rats was used for measuring autophagy proteins, vascular endothelial growth factor (VEGF) expression, and histological examination. On day 7 after surgery, the survival ratio of each flap was determined.

RESULTS

The expression of autophagy and VEGF in the second choke zone (choke II) was increased after flap surgery. Among the three groups, the survival ratio of flaps in the 3-MA group was the highest. Furthermore, the angiogenesis level in the 3-MA group in choke II was the highest among the three groups.

CONCLUSIONS

Autophagy was initiated by surgery in choke II, and VEGF expression in choke II was increased after flap surgery. Inhibiting autophagy after perforator flap surgery is beneficial for flap survival and for promoting angiogenesis in choke II.

Effect of Electroacupuncture at The Zusanli Point (Stomach-36) on Dorsal Random Pattern Skin Flap Survival in a Rat Model

BACKGROUND

Random skin flaps are commonly used for wound repair and reconstruction. Electroacupuncture at The Zusanli point could enhance microcirculation and blood perfusion in random skin flaps.

OBJECTIVE

To determine whether electroacupuncture at The Zusanli point can improve the survival of random skin flaps in a rat model.

MATERIALS AND METHODS

Thirty-six male Sprague Dawley rats were randomly divided into 3 groups: control group (no electroacupuncture), Group A (electroacupuncture at a nonacupoint near The Zusanli point), and Group B (electroacupuncture at The Zusanli point). McFarlane flaps were established. On postoperative Day 2, malondialdehyde (MDA) and superoxide dismutase were detected. The flap survival rate was evaluated, inflammation was examined in hematoxylin and eosin-stained slices, and the expression of vascular endothelial growth factor (VEGF) was measured immunohistochemically on Day 7.

RESULTS

The mean survival area of the flaps in Group B was significantly larger than that in the control group and Group A. Superoxide dismutase activity and VEGF expression level were significantly higher in Group B than those in the control group and Group A, whereas MDA and inflammation levels in Group B were significantly lower than those in the other 2 groups.

CONCLUSION

Electroacupuncture at The Zusanli point can effectively improve the random flap survival.

Effects of diammonium glycyrrhizinate on random skin flap survival in rats: An experimental study

Partial necrosis of skin flaps continues to restrict the survival of local skin flaps following plastic and reconstructive surgeries. The aim of the present study was to investigate the effects of diammonium glycyrrhizinate (DG), a salt of glycyrrhetinic acid that has been widely used in the therapy of chronic hepatitis and human immunodeficiency virus infection, on random skin flap survival in rats. McFarlane flaps were established in 60 male Sprague-Dawley rats randomly divided into three groups. Group I served as the control group and was injected with saline (10 mg/kg) once per day. Group II and group III were the experimental groups, and were injected with 10 mg/kg DG once and twice per day, respectively. On day 7, the survival area of the flap was measured. Tissue samples were stained with hematoxylin and eosin and immunohistochemically evaluated. Tissue edema, neutrophil density, superoxide dismutase (SOD) activity and malondialdehyde (MDA) levels were evaluated. The mean survival areas of the flaps of group II were significantly larger when compared with those of group I (P<0.05), and the rats of group III exhibited significantly higher survival areas than group II (P<0.05). Histologic and immunohistochemical evaluation showed that microvessel development and the expression level of vascular endothelial growth factor were higher in the two experimental groups than in the control group. Furthermore, SOD activity was significantly increased (P<0.05), while the neutrophil density and MDA level were significantly reduced (P<0.05) in group II when compared with group I. Significant differences between group II and group III with regard to SOD activity and MDA level were also observed (P<0.05). Thus, DG may have a dose-dependent effect on promoting the survival of random skin flaps.

Nano-microcapsule basic fibroblast growth factor combined with hypoxia-inducible factor-1 improves random skin flap survival in rats

The present study aimed to investigate the effect of nano-microcapsule-basic fibroblast growth factor (bFGF) combined with hypoxia-inducible factor-1 (HIF-1) on the random skin flap survival of rats. Male Sprague-Dawley rats were used to establish the McFarlane flap model and subsequently, all model rats were randomly divided into four groups: Control, bFGF, HIF-1 and bFGF combined with HIF-1. The model rats were treated with 2.5 µg/day bFGF and 1.0 µg/day HIF-1 for 5 days by intraperitoneal injection. On day 5 following treatment, the boundaries between necrotic and surviving regions were significantly inhibited by bFGF combined with HIF-1. bFGF combined with HIF-1 inhibited oxidative stresses and inflammatory factors in random skin flap survival of rats. bFGF combined with HIF-1 also activated the protein expression levels of cyclooxygenase (COX)-2 and vascular endothelial growth factor (VEGF) in the random skin flap survival of rats. In conclusion, nano-microcapsule bFGF combined with HIF-1 prevented random skin flap survival in rats through antioxidative, anti-inflammatory and activation of the protein expression levels of COX-2 and VEGF.

Inhibition of cyclooxygenase-1 and -2 activity in keratinocytes inhibits PGE2 formation and impairs vascular endothelial growth factor release and neovascularisation in skin wounds

Inhibition of cyclooxygenase (Cox) enzymatic activity by non-steroidal anti-inflammatory drugs (NSAIDs) provides the molecular basis of analgesia following wounding or surgery. This study investigated the role of Cox activity in the regulation of vascular endothelial growth factor (VEGF) expression in keratinocytes and the formation of new blood vessels in acute wounds in mice. To this end, human HaCaT keratinocytes were stimulated with epidermal growth factor (EGF). EGF increased Cox-1 mRNA in the presence of the constitutively expressed Cox-1 protein in keratinocytes. EGF coinduced Cox-2 and VEGF₁₆₅ mRNA and protein expression and an accumulation of prostaglandin E₂ (PGE₂ ) in cell culture supernatants. Inhibition of Cox isozyme activity by Cox-1 and -2 siRNA or ibuprofen reduced PGE₂ and VEGF₁₆₅ release from keratinocytes. In a mouse model of excisional wound healing, Cox-2 and VEGF₁₆₅ expression were colocalized in the granulation tissue of acute wounds. Oral treatment of mice with the Cox-1 and -2 inhibitor diclofenac was associated with reduced levels of VEGF₁₆₅ protein and an impaired blood vessel formation in acute wound tissue. In summary, our data suggest that a reduction of PGE₂ -triggered VEGF₁₆₅ protein expression in wound keratinocytes is likely to contribute to the observed impairment of wound neovascularisation upon Cox inhibition.

Experimental study of survival of pedicled perforator flap with flow-through and flow-end blood supply

BACKGROUND

Flap viability after transfer depends on blood flow from the arterial blood supply below the fascia. This study evaluated survival of a pedicle flap with a perforator lateral branch and flow-through blood supply, compared with that of a flap with a flow-end blood supply and perforator terminal branch.

METHODS

Forty Sprague-Dawley rats, 20 in each group, were assigned to transfer of a superficial epigastric artery pedicle island flap with a flow-through or flow-end configuration of blood supply. Laser Doppler imaging was used to evaluate flap perfusion 2 h, 3 days and 5 days after surgery. The rats were killed on day 5, and lead oxide-gelatine-enhanced flap angiography and histology with haematoxylin and eosin staining was performed. Dorsal midline tissue was excised for quantification of vascular endothelial growth factor by western blot assay.

RESULTS

On day 5 after surgery, the flow-through group exhibited a significantly greater mean(s.d.) flap survival area (97·8(3·5) versus 80·8(10·2) per cent; P = 0·003), microvascular density (303(19) versus 207(41) per mm(2) ; P < 0·001) and perfusion (8·64(0·14) versus 5·95(0·14) perfusion units; P < 0·001) than the flow-end group. The flow-through group exhibited more angiosomes connected by dilated vascular anastomoses between the skin and subcutaneous fasciae.

CONCLUSION

The flow-through blood supply improved pedicle perforator flap survival. Surgical relevance Perforator flap failure is mainly the result of impaired blood supply, as a flow-end blood configuration is nourished only by the perforator terminal branch of the artery. This work showed that the flow-through blood supply nourished by the perforator lateral branch improved flap survival, with dilatation of collateral vascular anastomoses and increased neoangiogenesis. The use of a flow-through configuration improves perforator flap survival and could therefore minimize morbidity resulting from flap necrosis.