Emodin activates autophagy to suppress oxidative stress and pyroptosis via mTOR-ULK1 signaling pathway and promotes multi-territory perforator flap survival.

BACKGROUND: Multi-territory perforator flap reconstruction has been proven effective in treating large skin and soft tissue defects in clinical settings. However, in view of that the multi-territory perforator flap is prone to partial postoperative necrosis, increasing its survival is the key to the success of reconstruction. In this study, we aimed to clarify the effect of emodin on multi-territory perforator flap survival. METHODS: Flap survival was assessed by viability area analysis, infrared laser imaging detector, HE staining, immunohistochemistry, and angiography. Western blotting, immunofluorescence assays, and real-time fluorescent quantitative PCR were performed to detect the indicators of oxidative stress, pyroptosis and autophagy. RESULTS: After emodin treatment, the multi-territory perforator flap showed a significantly increased survival rate, which was shown to be closely related to the inhibition of oxidative stress and pyroptosis and enhanced autophagy. Meanwhile, the use of autophagy inhibitor 3 MA was found to reverse the inhibitory effects of emodin on oxidative stress and pyroptosis and weaken the improving effect of emodin on flap survival, suggesting that autophagy plays a critical role in emodin-treated flaps. Interestingly, our mechanistic investigations revealed that the positive effect of emodin on multi-territory perforator flap was attributed to the mTOR-ULK1 signaling pathway activation. CONCLUSIONS: Emodin can inhibit oxidative stress and pyroptosis by activating autophagy via the mTOR-ULK1 pathway, thereby improving the multi-territory perforator flap survival.

M2 macrophage-derived exosomes induce angiogenesis and increase skin flap survival through HIF1AN/HIF-1α/VEGFA control.

BACKGROUND: Skin flap transplantation is a routine strategy in plastic and reconstructive surgery for skin-soft tissue defects. Recent research has shown that M2 macrophages have the potential for pro-angiogenesis during tissue healing. METHODS: In our research, we extracted the exosomes from M2 macrophages(M2-exo) and applied the exosomes in the model of skin flap transplantation. The flap survival area was measured, and the choke vessels were assessed by morphological observation. Hematoxylin and eosin (H&E) staining and Immunohistochemistry were applied to assess the neovascularization. The effect of M2-exo on the function of Human umbilical vein endothelial cells (HUVECs) was also investigated. We also administrated 2-methoxyestradiol (2-ME2, an inhibitor of HIF-1α) to explore the underlying mechanism. We tested the effects of M2-Exo on the proliferation of HUVECs through CCK8 assay and EdU staining assay. RESULTS: The survival area and number of micro-vessels in the skin flaps were increased in the M2-exo group. Besides, the dilation rate of choke vessels was also enhanced in the M2-exo group. Additionally, compared with the control group, M2-exo could accelerate the proliferation, migration and tube formation of HUVECs in vitro. Furthermore, the expression of the pro-angiogenesis factors, HIF-1α and VEGFA, were overexpressed with the treatment of the M2-exo. The expression of HIF1AN protein level was decreased in the M2-exo group. Finally, treatment with HIF-1α inhibitor reverses the pro-survival effect of M2-exo on skin flaps by interfering with the HIF1AN/HIF-1α/VEGFA signaling pathway. CONCLUSION: This study showed that M2-exosomes promote skin flap survival by enhancing angiogenesis, with HIF1AN/HIF-1α/VEGFA playing a crucial role in this process.

Comparison of retrograde anatomy iliac bone flap grafting versus anterograde anatomy iliac bone flap grafting for treatment of osteonecrosis of the femoral head.

BACKGROUND: Iliac bone flap with deep circumflex iliac artery is a common option in the treatment of Osteonecrosis of the femoral head (ONFH), and dissection of iliac bone flap is the key step for successful operation. This paper aims to introduce a new operative technique for dissecting iliac bone flap with deep circumflex iliac artery based on analysis of its advantages. METHODS: A total of 49 patients treated by retrograde anatomy and 52 patients treated by anterograde anatomy from January 2010 to December 2020 were recruited. The two groups were then compared in terms of the preoperative baseline conditions, intraoperative data, and postoperative Harris hip score (HHS). RESULTS: Compared with the retrograde anatomy group, the anterograde anatomy group had a significantly longer operating time, a significantly heavier intraoperative blood loss, a significantly higher rate of donor complication morbidity, a significantly higher rate of donor-recipient delayed healing, a significantly higher failure rate of iliac bone flap resection, a significantly higher rate of lateral femoral cutaneous nerve (LFCN) injury, and a significantly higher rate of ectopic ossification. No difference was found in postoperative HHS score between the two groups. CONCLUSION: As a new operative technique that can accurately locate the nutrient vessels of the iliac bone flap and quickly dissect the iliac bone flap with deep circumflex iliac artery while maintaining a comparable clinical effect, retrograde anatomy exhibited distinct advantages over anterograde anatomy in terms of simpler intraoperative operation, safer dissection, shorter operation time, lower blood loss, and fewer donor complications. LEVEL OF EVIDENCE: III, Retrospective.

Insight into Steroid-Induced ONFH: The Molecular Mechanism and Function of Epigenetic Modification in Mesenchymal Stem Cells.

Osteonecrosis of the femoral head (ONFH) is a common refractory orthopedic disease, which is one of the common causes of hip pain and dysfunction. ONFH has a very high disability rate, which is associated with a heavy burden to patients, families, and society. The pathogenesis of ONFH is not completely clear. At present, it is believed that it mainly includes coagulation dysfunction, abnormal lipid metabolism, an imbalance of osteogenic/adipogenic differentiation, and poor vascularization repair. The prevention and treatment of ONFH has always been a great challenge for clinical orthopedic surgeons. However, recent studies have emphasized that the use of mesenchymal stem cells (MSCs) to treat steroid-induced ONFH (SONFH) is a promising therapy. This review focuses on the role and molecular mechanism of epigenetic regulation in the progress of MSCs in the treatment of SONFH, and discusses the significance of the latest research in the treatment of SONFH from the perspective of epigenetics.

Itaconic acid induces angiogenesis and suppresses apoptosis via Nrf2/autophagy to prolong the survival of multi-territory perforator flaps.

Background: Perforator flaps are widely used in hand microsurgery to reconstruct and repair soft tissue injuries. However, ischemia and subsequent ischemia-reperfusion injury may cause distal necrosis of the flap. Itaconic acid (IA) is a modulator of macrophage function, which exerts anti-inflammatory effects in macrophage activation. Methods: The necrotic area of the flap was detected by measuring the flap temperature with an infrared thermometer. Flap cell apoptosis was detected by TUNEL staining and Western blot analysis of the apoptosis-associated proteins Bcl-2 and Bax. HE staining was used to detect angiogenesis of the skin flaps. CD31 was detected to identify positive vascular expression, and the survival of choke vessels in different areas of the skin flap was assessed by arteriography. In addition, Western blot was performed to quantify the expressions of VEGF, Nrf2, LC3II, SQSTM1, and CTSD. Results: Itaconic acid raises VEGF protein levels in skin flaps and the number of CD31-positive vessels. The skin flaps in the IA treatment group exhibited higher neovascularization and less necrosis than those in the control group. The results of TUNEL staining and Western blot revealed that Itaconic acid attenuated apoptosis in the ischemic area of flap. The combination of itaconic acid and Nrf2 inhibitor ML385 reversed this beneficial effect. The results revealed that itaconic acid attenuated apoptosis, enhanced angiogenesis, and enhanced autophagy. Conclusion: In summary, our findings indicate that itaconic acid might be an effective treatment to reduce flap necrosis. Additionally, this study identified a novel mechanism for the effects of itaconic acid on flap survival.

Waveform-arranged multiple skin paddles: A novel design to reconstruct complex soft tissue defects of the extremities with a modified multi-lobed perforator flap.

BACKGROUND: Multi-lobed perforator flap was one of popular approaches for one-stage reconstruction of complex soft tissue defects because of its minimal donor-site morbidity. However, the area of skin island that can be harvested on the donor site is limited on the angiosome distribution, Moreover, large defects require more than the conventional skin island provided by a traditional multi-lobed perforator flap. For further extended skin paddles, this study presented a novel design of waveform-arranged skin paddles to elevated a modified multi-lobed perforator flap for the reconstruction of complex soft tissue defects in the extremities. METHODS: From March of 2015 to March of 2020, fifteen patients underwent complex soft tissue defects reconstruction with waveform-arranged multi-lobed perforator flaps. According the size, shape and localization of the defects, two strategies were performed to design this modified multi-lobed flap. RESULTS: A total of fifteen waveform-arranged multi-lobed perforator flaps were successfully harvested to reconstruct complex soft tissue defects of the extremities. Among of them, Waveform-arranged dual skin paddles perforator flap were performed in eleven cases, and the waveform-arranged tripaddle perforator flaps were used in four cases. All the flaps survived and no flap related complication was observed postoperatively. The donor sites were closed directly in all cases. The mean follow-up time was 15.6 months. Most of the cases showed satisfactory contour. CONCLUSION: The waveform design of multi-lobed perforator flap was an alternative approach for reconstruction of complex soft tissue defects; it can maximize the harvested skin area of the donor site to provide extended skin island.

Melatonin Improved the Survival of Multi-Territory Perforator Flaps by Promoting Angiogenesis and Inhibiting Apoptosis via the NRF2/FUNDC1 Axis.

Background: Multi-territory perforator flaps are a reconstructive measure for repairing large soft tissue defects caused by tumors or trauma. However, the use of these flaps in clinical practice has been restricted due to the uncertain blood supply. Therefore, promoting the survival of the multi-territory perforator flap is critical for clinical repair and reconstruction. In our study, we explored the effects of melatonin (MLT) on multi-territory perforator flaps and the possible molecular mechanisms. Materials and Methods: Seventy-two Sprague-Dawley rats (250-300 g) were randomly divided into 3 groups (n = 24): Control, MLT and MLT + ML385 groups. First, we assessed the survival area of the flap, followed by the micro-vessel density and CD31-positive vessel expression. Apoptosis of the skin flap under immunofluorescence and expression of the apoptosis-related proteins Bcl-2, Bax and Caspase3 were measured. Additionally, angiogenesis of the skin flaps was shown by angiography, and NRF2 and FUNDC1 mRNA and protein expression was detected by real-time PCR and western blotting. Results: The results showed that MLT increased the survival area of the multi-territory perforator flap, which was related to increased angiogenesis and decreased apoptosis. We also found that mRNA and protein of NRF2 and FUNDC1 levels were significantly increased after MLT treatment, and an NRF2 inhibitor reversed the ability of MLT to enhance multi-territory perforator flap survival, promote angiogenesis and inhibit apoptosis and reduced FUNDC1 protein expression. Conclusion: MLT promoted angiogenesis and inhibited apoptosis to promote the survival of multi-territory perforator flaps, which may be regulated via the NRF2/FUNDC1 axis.