Protective effects of icariin on dorsal random skin flap survival: An experimental study

Skin Tolerability of Oleic Acid Based Nanovesicles Designed for the Improvement of Icariin and Naproxen Percutaneous Permeation

Deformable nanovesicles have a crucial role in topical drug delivery through the skin, due to their capability to pass intact the stratum corneum and epidermis (SCE) and significantly increase the efficacy and accumulation of payloads in the deeper layers of the skin. Namely, lipid-based ultradeformable nanovesicles are versatile and load bioactive molecules with different physicochemical properties. For this reason, this study aims to make oleic acid based nanovesicles (oleosomes) for the codelivery of icariin and sodium naproxen and increase their permeation through the skin. Oleosomes have suitable physicochemical properties and long-term stability for a potential dermal or transdermal application. The inclusion of oleic acid in the lipid bilayer increases 3-fold the deformable properties of oleosomes compared to conventional liposomes and significantly improves the percutaneous permeation of icariin and sodium naproxen through the human SCE membranes compared to hydroalcoholic solutions of both drugs. The tolerability studies on human volunteers demonstrate that oleosomes are safer and speed up the recovery of transepidermal water loss (TEWL) baselines compared to saline solution. These results highlight promising properties of icariin/sodium naproxen coloaded oleosomes for the treatment of skin disorders and suggest the potential future applications of these nanovesicles for further in vivo experiments.

Extracellular Vesicles Isolated From Hypoxia-Preconditioned Adipose-Derived Stem Cells Promote Hypoxia-Inducible Factor 1α-Mediated Neovascularization of Random Skin Flap in Rats

BACKGROUND

Random flaps are widely used for wound repair. However, flap necrosis is a serious complication leading to the failure of operation. Our previous study demonstrated a great proangiogenic potential of hypoxia-treated adipose-derived stem cells-extracellular vesicles (HT-ASC-EVs). Thus, we aim to evaluate the effect of HT-ASC-EVs in the survival and angiogenesis of random skin flap in rats.

METHODS

Adipose-derived stem cells-extracellular vesicles were respectively isolated from adipose-derived stem cell culture medium of 3 donors via ultracentrifugation. The expression of hypoxia-inducible factor 1α (HIF-1α) and proangiogenic potential of HT-ASC-EVs and ASC-EVs were compared by co-culturing with human umbilical vein endothelial cells. Forty male Sprague-Dawley rats were randomly divided into 3 group (n = 10/group). A 9 × 3-cm random skin flap was separated from the underlying fascia with both sacral arteries sectioned on each rat. The survival and angiogenesis of flaps treated by ASC-EVs or HT-ASC-EVs were also compared. Laser Doppler flowmetry and immunohistochemistry were used to evaluate skin perfusion and angiogenesis of skin flaps on postoperative day 7.

RESULTS

Hypoxia-treated adipose-derived stem cells-extracellular vesicles further improve the proliferation, migration, tube formation with upregulated HIF-1α, and VEGF expression of human umbilical vein endothelial cells in vitro, compared with ASC-EVs. In vivo, postoperatively injecting HT-ASC-EVs suppressed necrosis rate (29.1 ± 2.8% vs 59.2 ± 2.1%) and promoted the angiogenesis of skin flap including improved skin perfusion (803.2 ± 24.3 vs 556.3 ± 26.7 perfusion unit), increased number of CD31-positive cells, and upregulated expression of HIF-1α in vascular endothelium on postoperative day 7, compared with ASC-EVs.

CONCLUSIONS

Intradermal injecting HT-ASC-EVs improve the survival of random skin flap by promoting HIF-1α-mediated angiogenesis in rat model.

The Promising Effect of Topiramate on Random-Pattern Skin Flap Survival in Rats

BACKGROUND

Partial necrosis of skin flaps following plastic and reconstructive surgeries is one of the major problems in these medical interventions. This study was conducted to evaluate the beneficial effects of topiramate an anti-epileptic agent on ischemic random skin flaps.

MATERIALS AND METHODS

Twenty-four Wistar rats were provided and randomly divided into four experimental groups (control group and low-, intermediate- and high-dose treatment groups). A rat random-pattern skin flap model was performed in all groups, and animals in the low-, intermediate- and high-dose experimental groups were administered topiramate intraperitoneally at doses of 25, 50 and 100 mg/kg, respectively, 1 h before raising the flap and once daily for 7 consecutive days after the initial surgical procedure. Control rats received vehicle according to the same schedule. On postoperative day 7 the flap necrotic area was measured, and tissue samples were stained with hematoxylin and eosin for histological analysis. Furthermore, the oxidative stress in flap tissue was assessed by measuring the activity of superoxide dismutase (SOD), glutathione (GSH) level and the content of malondialdehyde (MDA).

RESULTS

Treating animals with 50 and 100 mg/kg topiramate significantly decreased the necrotic flap areas as compared to the control group. Histological studies demonstrated that in intermediate and high dose topiramate groups the inflammatory cell numbers were attenuated and microvessel development were markedly increased. Furthermore, the MDA contents were significantly reduced and GSH levels were significantly increased in these groups as compared to the control group. However, the SOD activity was increased significantly only in high-dose group as compared to the control group.

CONCLUSIONS

These findings indicated that topiramate in doses of 50 and 100 mg/kg increases random skin flap survival.

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Tissue-Protective Mechanisms of Bioactive Phytochemicals in Flap Surgery

Despite careful preoperative planning, surgical flaps are prone to ischemic tissue damage and ischemia–reperfusion injury. The resulting wound breakdown and flap necrosis increase both treatment costs and patient morbidity. Hence, there is a need for strategies to promote flap survival and prevent ischemia-induced tissue damage. Phytochemicals, defined as non-essential, bioactive, and plant-derived molecules, are attractive candidates for perioperative treatment as they have little to no side effects and are well tolerated by most patients. Furthermore, they have been shown to exert beneficial combinations of pro-angiogenic, anti-inflammatory, anti-oxidant, and anti-apoptotic effects. This review provides an overview of bioactive phytochemicals that have been used to increase flap survival in preclinical animal models and discusses the underlying molecular and cellular mechanisms.

Febuxostat treatment attenuates oxidative stress and inflammation due to ischemia-reperfusion injury through the necrotic pathway in skin flap of animal model

BACKGROUND

Ischemia-reperfusion (I/R) injury is a major contributor to skin flap necrosis, which is a serious complication of reconstructive surgery. The purpose of this study was to evaluate the protective effect of treatment with febuxostat, a selective xanthine oxidase inhibitor, on I/R injury in the skin flap of an animal (rat) model.

METHODS

Superficial epigastric flaps were raised in Sprague-Dawley rats and subjected to ischemia for 3 h. Febuxostat at a dose of 10 mg/kg/day was administered to rats in drinking water from 1 week before the surgery (Feb group). Control animals received no drugs (Con group). The mean ratio of flap survival and contraction was evaluated and compared between animals with and without administration of febuxostat on day 5 after the surgery. In addition, infiltration by polymorphonuclear leukocytes and muscles of the panniculus carnosus in the flap were histologically evaluated using hematoxylin-eosin staining. Furthermore, xanthine oxidase activity, ATP levels, superoxide dismutase activity, and expression of 8-hydroxy-2'-deoxyguanosine (8-OHdG), tumor necrosis factor-α, and interleukin-1β were quantitatively assessed in the skin flap 24 h after the surgery.

RESULTS

In the Feb group, the survival and contraction rates at the 5 d timepoint post-surgery were significantly higher and lower than those in the Con group, respectively. Histological analysis showed significant reduction in polymorphonuclear leukocyte infiltration and muscle injury scores due to I/R injury in the Feb group. The expression of 8-OHdG was also significantly inhibited in animals administered febuxostat. Biochemical analysis showed a significant reduction in xanthine oxidase activity and significant increases in ATP levels and superoxide dismutase activity in the Feb group. Furthermore, the expression of interleukin-1β was significantly lower in the Feb group than in the Con group.

CONCLUSION

Febuxostat, which is clinically used for the treatment of hyperuricemia, was effective against necrosis of the skin flap via inhibition of oxidative stress and inflammation caused by I/R injury.

Superiority of Adipose-derived CD34 + Cells over Adipose-derived Stem Cells in Promoting Ischemic Tissue Survival

BACKGROUND

Tissue ischemia usually leads to necrosis and is a threatening condition associated with reconstructive surgery. Promoting the survival of ischemic tissue is critical for improving clinical outcomes. Although various solutions based on stem cells have been reported, there are still limitations to clinical translation. The aim of this study was to develop an effective method to promote the survival of ischemic tissue.

METHODS

Adipose-derived CD34 + and CD34- cells were obtained by magnetic bead sorting from the stromal vascular faction (SVF). Adipose-derived stem cells (ADSCs) were collected by subculture. The angiogenic capacities of CD34 + cells, CD34- cells and ADSCs were evaluated in vitro by comparing mRNA and protein expression. Random axial flaps in nude mice were used to evaluate the efficacy of these cells in protecting tissue from necrosis. The effect of these cells in preventing inflammation was also evaluated.

RESULTS

Our data suggest that CD34 + cells expressed higher levels of angiogenetic factors and lower levels of inflammatory factors than the other cell types. More vessel branches were formed when human umbilical vein endothelial cells (HUVECs) were treated with conditioned medium from CD34 + cells than conditioned medium from the other cell types. Compared to ADSCs, CD34 + cells showed significantly higher efficacy in promoting tissue survival. More CD31 + cells and higher levels of angiogenic factors were observed in tissues from the CD34 + group than in those from the other groups. Lower levels of the proinflammatory factors TNF-α and IL-1b and higher levels of anti-inflammatory factors were found in the CD34 + group than in the other groups.

CONCLUSION

Adipose-derived CD34 + cells showed better efficacy in improving ischemic tissue survival than ADSCs by reducing tissue inflammation and promoting angiogenesis. CD34 + cells can be obtained easily and may be suitable for clinical applications.

Postconditioning With Red-Blue Light Therapy Improves Survival of Random Skin Flaps in a Rat Model

BACKGROUND

Random skin flap ischemic necrosis is a serious challenge in reconstructive surgery. Photobiomodulation is a noninvasive effective technique to improve microcirculation and neovascularization. Photobiomodulation with red or blue light has been separately proven to partially prevent skin flap necrosis, but the synergistic effect of red and blue light not been elucidated. Our experiment evaluated the impact of postconditioning with red-blue light therapy on the viability of random flaps.

METHODS

Thirty Sprague-Dawley male rats (male, 12 weeks) with a cranially based random pattern skin flap (3 × 8 cm) were divided into 3 groups: control group, red light group, and red-blue light group. On postoperative day 7, flap survival was observed and recorded using transparent graph paper, flaps were obtained and stained with hematoxylin and eosin, and microvessel density was measured. Micro-computed tomography was used to measure vascular volume and vascular length. On days 0, 3, and 7 after surgery, blood flow was measured by laser Doppler. To investigate the underlying mechanisms, the amount of nitric oxide (NO) metabolites in the flap tissue was assessed on days 3, 5, and 7 after surgery.

RESULTS

The mean percentage of skin flap survival was 59 ± 10% for the control group, 69 ± 7% for the red light group, and 79 ± 9% for the red-blue light group (P < 0.01). The microvessel density was 12.3 ± 1.2/mm2 for the control group, 31.3 ± 1.3/mm2 for the red light group, and 36.5 ± 1.4/mm2 for the red-blue light group (P < 0.01). Both vascular volume and total length in the red-blue light group showed significantly increased compared with the red light and control group (P < 0.01). Blood flow in the red-blue light treated flap showed significantly increased at postsurgery days 3 and 7 compared with the red light and control group (P < 0.01). The level of the NO metabolites was significantly increased in flap tissues belonging to the red-blue light group compared with the other 2 groups (P < 0.01).

CONCLUSIONS

This study showed that postconditioning with red-blue light therapy can enhance the survival of random skin flap by improving angiogenesis and NO releasing.