Survival Rate Of Skin Flap Research Articles

Caffeic acid-vanadium nanozymes treat skin flap ischemia-reperfusion injury through macrophage reprogramming and the upregulation of X-linked inhibitors of apoptotic proteins

Ischemia-reperfusion (I/R) injury following skin flap transplantation is a critical factor leading to flap necrosis and transplant failure. Antagonizing inflammatory responses and oxidative stress are regarded as crucial targets for mitigating reperfusion injury and enhancing flap survival. In this study, caffeic acid-vanadium metal polyphenol nanoparticles (CA-V NPs) were prepared for the treatment of skin flap ischemia and reperfusion. This study was conducted using a one-step method to prepare new types of CA-V NPs with uniform sizes and stable structures. In vitro, the CA-V NPs exhibited CAT-like and SOD-like activities and could effectively scavenge ROS, generate oxygen, and alleviate oxidative stress. In the H2O2-induced cellular oxidative stress model, CA-V NPs effectively reduced ROS levels and inhibited apoptosis through the XIAP/Caspase-3 pathway. In the cellular inflammation model induced by LPS combined with IFN-γ, CA-V NPs reprogrammed macrophage polarization toward the M2 phenotype and reduced inflammatory responses by reducing the expression of the chemokines CCL4 and CXCL2. In addition, animal experiments have shown that CA-V NPs can alleviate oxidative stress in skin flap tissues, inhibit apoptosis, promote angiogenesis, and ultimately improve the survival rate of skin flaps. CA-V NPs provide a new target and strategy for the treatment of flap I/R injury.

Tetrahydropalmatine promotes random skin flap survival in rats via the PI3K/AKT signaling pathway

Ethnopharmacological relevanceFlap necrosis is the most common complication after flap transplantation, but its prevention remains challenging. Tetrahydropalmatine (THP) is the main bioactive component of the traditional Chinese medicine Corydalis yanhusuo, with effects that include the activation of blood circulation, the promotion of qi, and pain relief. Although THP is widely used to treat various pain conditions, its impact on flap survival is unknown. Aim of the studyTo explore the effect and mechanism of THP on skin flap survival. Materials and methodsIn this study, we established a modified McFarlane flap model, and the flap survival rate was calculated after 7 days of THP treatment. Angiogenesis and blood perfusion were evaluated using lead oxide/gelatin angiography and laser Doppler, respectively. Flap tissue obtained from zone II was evaluated histopathologically, by hematoxylin and eosin staining, and in assays for malondialdehyde content and superoxide dismutase activity. Immunofluorescence was performed to detect interleukin (IL)-6, tumor necrosis factor (TNF)-α, hypoxia-inducible factor (HIF)-1α, Bcl-2, Bax, caspase-3, caspase-9, SQSTM1/P62, Beclin-1, and LC3 expression, and Western blot to assess PI3K/AKT signaling pathway activation and Vascular endothelial growth factor (VEGF) expression. The role played by the autophagy pathway in flap necrosis was examined using rapamycin, a specific inhibitor of mTOR. ResultsExperimentally, THP improved the survival rate of skin flaps, promoted angiogenesis, and improved blood perfusion. THP administration reduced the inflammatory response, oxidative stress, and apoptosis in addition to inhibiting autophagy via the PI3K/AKT/mTOR pathway. Rapamycin partially reversed these effects. ConclusionTHP promotes skin flap survival via the PI3K/AKT signaling pathway.

Chronic Cinacalcet improves skin flap survival in rats: the suggested role of the nitric oxide pathway.

Cinacalcet is a calcimimetic medicine that has been used to treat secondary hyperparathyroidism and parathyroid cancer. Various studies have proposed the positive role of calcium and its receptor in skin wound healing. Furthermore, Cinacalcet interacts with other skin repair-related mechanisms, including inflammation and nitric oxide pathways. The present study evaluated the effect of Cinacalcet on the random-pattern skin flap survival. Eighty-four Wistar male rats were used. Multiple doses of Cinacalcet (30, 3, 1, 0.3, and 0.05 mg/kg) were used in 3 different routes of administration before the surgery. Histopathological evaluations, quantitative assessment of IL-6, TNF-α, and nitric oxide (NO), and the expression of calcium-sensing receptor (CaSR) and E-cadherin were evaluated in the skin tissue. To assess the role of NO, a NO synthase inhibitor, N-nitro-L-arginine methyl ester hydrochloride (L-NAME), was used, and histopathological effects were investigated. Cinacalcet pretreatment at the IP chronic 1 mg/kg dose significantly increased the skin flap survival rate and enhanced the NO tissue level compared to the control. However, the administration of L-NAME abolished its protective effects. IP Chronic 1 mg/kg of Cinacalcet could also decline the levels of IL-6 and TNF-α and also increase the expression of CaSR and E-cadherin in the flap tissue compared with the control group. Chronic Cinacalcet at 1 mg/kg could improve skin flap survival, probably mediated by the CaSR, NO, and inflammation-related pathways.

Effect of adipose derived stem cells on the survival rate of long random pattern skin flap in rats, and the underlying mechanism of action

Purpose: To investigate the effect of adipose-derived stem cells (ADSCs) on the survival rate of long random pattern skin flaps in rats and the likely underlying mechanism.
 Methods: Twenty (20) SPF-grade SD rats were randomly divided into control group and study group, with 10 rats in each group. Rats in the control group were given phosphate buffered saline (PBS), while rats in the study group received ADSCs. The survival rate of the skin flaps was compared between the 2 groups on day 7 after operation, while the levels of indices related to oxidative stress and inflammatory response were compared on the 7th and 14th days after operation.
 Results: Necrosis in the study group was milder (p < 0.05). On the 7th post-operation day, the survival rate of rat skin flap in the study group was significantly higher than that in the control group (p < 0.05), but the MDA level in the study group was lower than that of the control group (p < 0.05). On the 14th day after the operation, the MDA level was decreased in the two groups (p < 0.05), with a lower MDA level in the study group than in the control group (p < 0.05).
 Conclusion: ADSCs inhibit inflammatory response and reduces the level of oxidative stress after long random pattern skin flap transplantation in rats, thereby enhancing blood supply to the flap transplantation area and improving its survival rate. Thus, ADSCs have a potential clinical application in enhancing blood supply in skin transplantation.

Therapeutic potential of naringin in improving the survival rate of skin flap: A review.

Naringin is the main component of Drynaria. Modern pharmacological studies have shown that naringin has a wide range of pharmacological activities, including antioxidant, anti-inflammatory, anti-apoptotic, anti-ulcer, and anti-osteoporosis effects. Its therapeutic effects have been observed in various clinical models, such as atherosclerosis, cardiovascular diseases, diabetes, neurodegenerative diseases, and rheumatic diseases. This review investigates the pharmacological effects of naringin and the associated mechanisms in improving flap survival. This review will also provide a reference for future rational application of naringin, especially in research to improve flap survival.

Application of VSD technique in adults with chronic osteomyelitis of the extremities combined with soft tissue defects.

To investigate the clinical application of vacuum sealing drainage (VSD) in chronic osteomyelitis of the extremities combined with soft tissue defects in adults. This study retrospectively included 32 adult patients with clearly diagnosed chronic osteomyelitis of the extremities combined with local soft tissue defects, and the trauma was covered by VSD after debridement, osteotomy, and vancomycin-laden bone cement filling of the occupancy, and the trauma was covered by selecting a suitable flap transfer repair according to the site and extent of the soft tissue defect after the trauma condition was suitable, and the secondary trauma was taken from the abdominal full-thickness skin free skin slice graft, according to whether the skin graft area was performed. The skin flap hematoma and infection rate, as well as the skin flap survival rate and implant fixation time were compared and analysed between the two groups. The primary outcome is the implant fixation time, and the secondary outcome is the skin fragment survival rate. In 32 patients, VSD was performed on the bone cement surface to cover the trauma, and 33.2 to 39.8kPa continuous vacuum sealing drainage was set. The average VSD time duration before soft tissue coverage was 47.87 ± 23.14 days, and the average number of VSD use was 7.18 ± 3.23. The use of VSD before soft tissue coverage did not cause complications such as negative pressure could not be maintained, vacuum sealing drainage was not smooth, skin blistering, trauma. Among the 32 patients, 12 cases of soft tissue coverage were followed by trauma free skin grafting with packing + VSD, and 20 cases were fixed with packing alone, and the duration of continuous packing and fixation of free skin pieces in the VSD group was significantly less than that in the control group (P=.006). The survival rate was significantly higher than that of the control group (P=.019). VSD in adult patients with chronic osteomyelitis of the extremities combined with soft tissue defects can effectively improve the trauma condition, provide the possibility of second-stage soft tissue coverage, and significantly shorten the preparation time for soft tissue coverage. In addition, when soft tissue coverage trauma is performed, VSD combined with skin graft packing technique can significantly improve the survival rate of skin pieces, shorten the time of skin graft fixation.

SDF-1 Functionalized Hydrogel Microcarriers for Skin Flap Repair.

Critically sized skin flaps used to treat skin defects often suffer from necrosis due to insufficient blood supply. Hence there is an urgent need to improve the survival rate of skin flaps by promoting local angiogenesis. The delivery of growth factor loaded microcarriers have shown promise in enhancing defect repair, however, their rapid clearance from the defect site limits their regenerative potential. Thus, it is critical to develop microcarriers which can promote the sustained release of bioactive factors to effectively stimulate tissue repair. This study aimed to develop a stromal cell-derived factor 1 (SDF-1) loaded microcarrier coated with Matrigel (MC@SDF-1@Mat) to promote skin flap repair. SEM imaging showed that the surface of the microcarrier was coated by a porous Matrigel film. The drug release experiment showed that the Matrigel-coated microcarriers enhanced the sustained release of the model drug methylene blue when compared to uncoated group. MC@SDF-1@Mat significantly promoted the proliferation, migration, and angiogenesis of HUVECs via CCK-8, wound healing assay, and tube formation assay, respectively. Moreover, the murine random skin flap model was further established and treated. It was found that the flap necrosis area in the MC@SDF-1@Mat treated group was significantly reduced. H&E and Masson staining showed the histological structure and collagen organization exhibited a normal phenotype in the MC@SDF-1@Mat treated group. Additionally, CD31 immunohistochemical analysis showed that the MC@SDF-1@Mat treated group exhibited the greatest degree of neovascularization. In conclusion, our SDF-1 functionalized gelatin-based hydrogel microcarrier has potential clinical applications in promoting skin flap repair and drug delivery.

Prussian Blue Nanozyme Promotes the Survival Rate of Skin Flaps by Maintaining a Normal Microenvironment.

Ischemia-reperfusion (I/R) injury leads to a low success rate of skin flap transplantation in reconstruction surgery, thus requiring development of new treatments. Necroptosis and apoptosis pathways, along with overexpression of reactive oxygen species and pro-inflammatory factors in skin flap transplantation, are deemed as potential therapeutic targets. This study provides a paradigm for nanozyme-mediated microenvironment maintenance to improve the survival rate of the transplanted skin flap. Prussian blue nanozyme (PBzyme) with multiple intrinsic biological activities was constructed and selected for this proof-of-concept study. The prepared PBzyme shows anti-inflammatory, antiapoptotic, antinecroptotic, and antioxidant activities in both in vitro and in vivo models of I/R injured skin flaps. The multiple inhibitory effects of PBzyme maintained a normal microenvironment and thus significantly promoted the survival rate of the I/R injured skin flap (from 37.21 ± 8.205% to 79.61 ± 7.5%). Of note, PBzyme regulated the expression of the characteristic signal molecules of necroptosis, including Rip 1, Rip 3, and pMLKL, indicating that PBzyme may be a therapeutic agent for necroptosis-related diseases. This study shows great prospects for clinical application of PBzyme in the treatment of skin flaps via local administration.

Diallyl Trisulfide Enhances the Survival of Multiterritory Perforator Skin Flaps.

The multiterritory perforator flap is one of the widest flap patterns used to repair tissue defects. However, flap necrosis of the distal part is still a challenging issue for plastic surgeons. Diallyl trisulfide (DATS) is an efficient ingredient extracted from garlic, exerting many important effects on different diseases. Our experiment aims to reveal whether DATS has a beneficial effect on the survival of perforator flaps and to explore its mechanism of action. The results showed that DATS enhanced angiogenesis and autophagy and reduced cell apoptosis and oxidative stress, thereby improving the survival rate of skin flaps. After co-administration with autophagy inhibitor 3-methyladenine (3MA), perforator flap survival was further improved. Mechanistically, we showed that PI3K/Akt and AMPK-HIF-1α signaling pathways in flap were activated under DATS treatment. All in all, DATS promoted the survival of multiterritory perforator flaps via the synergistic regulation of PI3K/Akt and AMPK-HIF-1α signaling pathways, and inhibition of DATS-induced autophagy further improves flap survival.

Features of Preoperative Preparation of Patients with Burns and Chronic Ulcers of Various Etiology for Autodermoplasty

The influence of various schemes of preoperative preparation for autodermoplasty on the rates of skin graft survival and the duration of hospitalization in patients with burns and wounds of various etiologies was analyzed. Patients were divided into groups and subgroups depending on the preparation scheme. Group I (22 patients) received negative pressure wound therapy (NPWT) during the preoperative period for 5 days in combination with reamberin — intravenous drip at a rate of 40-60 drops/min, 500 ml, once a day for 5 days. Those patients were divided into subgroups: subgroup 1A (17 people) received complex treatment without antibiotic therapy, subgroup 1B (5 people) received antibiotic therapy. Group II consisted of 30 patients, who received vacuum therapy during the preparatory period. Group II patients were also divided into subgroups: 2A (16 people) received NPWT without antibiotics, 2B (14 people) — vacuum therapy together with antibiotic therapy. Group III (comparison, n=52) included patients who were treated using traditional methods, including antibiotic therapy and topical use of various dressings and ointments. Follow-up morphohistological study of wound biopsies was carried out in order to determine the area of fibroblasts, the area of fibroblast nucleus, and the number of vessels. After skin autografting, skin flap survival rate was determined, taking the time of hospitalization into account. Upon comparison of preoperative preparation schemes used for patients with burns and chronic ulcers of various etiologies with a surface area of 1–5% appropriate for skin autografting, the scheme that included NPWT and reamberin for 5 days proved to be the most effective: an improvement in fibroblastogenesis and blood flow to the wound was noted in this group of patients, which was accompanied by an improvement in the skin flap survival rate up to 90.0±9.9%, which, in turn, reduced the duration of patient’s hospital stay — the average duration of the preoperative period was 2.5 times shorter, postoperative — 1.9 times shorter than in the comparison group (p<0.05). The results obtained make it possible to recommend the use of this scheme in the preoperative preparation for skin autografting for patients with burns and chronic ulcers of various etiologies with the surface area of 1–5%.

Application and effect evaluation of nursing quality target management in free flap transplantation for hand injury.

To explore application and effect of nursing quality target management in free flap transplantation for hand injury. 140 patients with free skin flap transplantation for hand injury admitted to the hand and foot surgery ward of the hospital from January 2017 to December 2019 were selected as the research objects. They were randomly divided into observation group and control group. There were 70 patients in each group, and both groups of patients received microscopic free flap transplantation. The observation group adopted traditional nursing mode and nursing quality target management mode to carry out nursing, while the control group adopted traditional nursing mode to carry out nursing. The treatment compliance, skin flap survival, occurrence of vascular crisis, occurrence of complications, VAS and Barthel comparison score of the two groups were compared. The treatment compliance of patients in the observation group was significantly higher than that in the control group (P < 0.05). The survival rate of skin flap in the observation group was higher than that in the control group (P < 0.05). The incidence of vascular crisis in the observation group was lower than that in the control group (P < 0.05). The postoperative pain in the observation group was better than that in the control group (P < 0.05). There was no significant difference in Barthel score between the observation group and the control group at admission (P > 0.05), but the improvement range of Barthel score in the observation group was higher than that in the control group at discharge (P < 0.05), The satisfaction of patients in the observation group to nurses was higher than that in the control group (p < 0.05). The application of nursing quality target management can improve the treatment compliance of patients, improve the survival rate of free skin flap transplantation for hand injury, reduce the incidence of vascular crisis within 48 hours after operation, reduce the occurrence of postoperative complications, relieve the pain of patients, improve self-care ability and ensure the quality of life.

Effects of Atorvastatin Calcium on the Survival of Ultra-long Dorsal Random Skin Flaps in Rats

To investigate the effects of atorvastatin calcium (ATR) on the survival of ultra-long dorsal random skin flaps in rats. Thirty SD rats were divided into five groups ( n=6) according to the random number table: normal saline control group (CON group), ATR 10 mg/kg group (P10 group), ATR 20 mg/kg group (P20 group), ATR 30 mg/kg group (P30 group), and ATR 40 mg/kg group (P40 group). After pretreatment with ATR or 0.9% saline for 3 days, an ultra-long dorsal random skin flaps with size of 8 cm×2 cm was made on the back of each rat and replanted in situ. After the operation, the ATR or saline treatment lasted for 3 d. Seven days after operation, the appearance of skin flaps was observed with naked eyes, the survival rate of skin flaps was calculated. The pathological changes in the surviving areas of skin flaps were observed by HE staining, the number of microvessels in skin flaps was observed by immunohistochemistry staining, the mRNA expressions of vascular endothelial growth factor ( VEGF) and basic fibroblast growth factor ( bFGF) were tested by quantitative real-time PCR, and the contents of superoxide dismutase, nitrogen monoxide and malonaldehyde were tested by enzyme linked immunosorbent assays (ELISA). On the 7 thday after operation, the skin flap of the CON group showed a large area of necrosis, and the necrotic part formed crusts. Crusts were hard and inelastic, and a large amount of tissue fluid exudated. The fascial layer showed dark purple. No exudation of tissue fluid was observed in the flaps of P10, P20, P30 and P40 groups. The scab shell fell off naturally and the fur grew normally. HE staining of CON group showed that a large number of inflammatory cell infiltration, epidermal loss and necrosis in skin flaps, but the pathological changes in skin flaps were significantly improved after treatment with ATR. Compared with the CON group, the survival rate of skin flaps, the number of microvessels in skin flaps and the levels of VEGF mRNA, bFGF mRNA, SOD, NO in skin flaps also increased with the dose of ATR, which reached a peak at 30 mg/kg ATR ( P<0.05). However, the level of MDA in skin flaps decreased with the dose of ATR, which reached the lowest at 30 mg/kg ATR ( P<0.05). ATR can enhance the survival of ultra-long dorsal random skin flaps in rats, which may be related to promoting microangiogenesis and inhibiting inflammatory and oxidative stress.

"Point line anterograde dissection" for the safe preparation of supraclavicular flap

Objective: To investigate the application in the preparation of supraclavicular island flap by "point line anterograde dissection (PLAD) ". Methods: A retrospective analysis was performed on 45 flaps of 43 patients treated with supraclavicular artery island flap from the Department of Otorhinolaryngology Head and Neck Surgery, Beijing Tongren Hospital Affiliated to Capital Medical University from January 2013 to June 2019. The patients were all male, aged 35-72 years old. There were 26 cases of hypopharyngeal cancer, 4 cases of recurrent laryngeal cancer, 2 cases of cervical esophageal cancer, 1 case of tonsillar cancer, 1 case of parotid gland cancer, 3 cases of postoperative pharyngeal fistula after hypopharyngeal cancer, 2 cases of esophageal fistula after trauma, 2 cases of esophageal stricture after hypopharyngeal carcinoma operation, 1 case of autoimmune laryngeal stenosis, and 1 case of cheek defect after maxillary sinus cancer operation."Point" was the origin of the supraclavicular artery in the transverse carotid artery. "Line" was an extension line made along the starting point of the supraclavicular vessel for anterograde anatomy of 1-2 cm and the direction of the blood vessel. The extension line was used as the central axis of the designed island flap. Characteristics of flap blood supply, the time of flap preparation, flap survival, donor area recovery and clinical follow-up were recorded. Results: The arterial blood supply of the flap was constant, and the venous reflux was variable. The area of the prepared flap was (4-8) cm×(10-18) cm, and the preparation time was 30-60 min, with a median of 42 min. Skin flap survival rate was 100%. Partial necrosis of skin flap occurred in 1 patient and postoperative pharyngeal fistula occurred in 5 patients, all of whom were cured by dressing change. The donor site defects were closed and sutured directly. 3 patients had partial incision dehiscence and healed after dressing change. During the follow-up, 1 patient was lost, and the remaining 42 patients were followed up for 8 to 55 months.40 patients involved swallowing function, all of them returned to regular diet or soft fluid after operation.40 patients involved malignant tumors and local tumor recurrence in 3 patients among whom, there were 2 cases of lymph node recurrence, and 2 cases of distant metastasis, including 1 case of lung metastasis and 1 case of bone metastasis. Conclusion: PLAD is a simple, safe and efficient method for the preparation of supraclavicular island flap.

Effect of natural hirudin on revascularization of ischemic skin flaps in rats by Micro-CT

To investigate the effect of natural hirudin on revascularization of ischemic skin flap in rats using Micro-CT and three-dimensional (3D) reconstruction. Thirty-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. Both 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). Natural 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.

D-allose alleviates ischemia/reperfusion (I/R) injury in skin flap via MKP-1

BackgroundD-allose was promising in the protection of ischemia/reperfusion (I/R) injury. We intended to investigate the function of D-allose in skin flap of rat followed by the injury of I/R and whether ERK signal pathway was involved in.MethodsThe back flap of Wistar rats was picked up with a vascular bundle of the lateral chest wall. I/R model was made by the venous clamp for 6 h. Rats received D-allose and PD-98059, the inhibitor of ERK1/2, 30 min before modeling. Morphology of tissue was observed by HE staining. Nitric oxide (NO), myeloperoxidase (MPO), malondialdehyde (MDA) and superoxide dismutase (SOD) levels in skin flap were determined by ELISA kits. mRNA and protein levels were determined by qPCR and Western blot respectively.ResultsD-allose alleviated the condition of pathological changes and raised the survival rate of skin flap injured by I/R. Moreover, D-allose suppressed NO, MPO and MDA while elevated SOD levels during I/R status. Furthermore, D-allose decreased MCP-1, TNF-α, IL-1β and IL-6 levels in skin flap injured by I/R. In addition, D-allose inhibited MKP-1 expression and activated ERK1/2 pathway in skin flap injured by I/R. PD-98059 partially counteracted D-allose effects on I/R injury.ConclusionsD-allose exerted its protective function via inhibiting MKP-1expression and further activated ERK1/2 pathway to suppress the progress of oxidative stress, inflammation and necrosis, contributing to the survival of skin flap injured by I/R. Thus, D-allose was promising in the transplantation of skin flap.

Effect of adipose-derived stem cell derived exosomes on angiogenesis after skin flap transplantation in rats

To investigate the effect of adipose-derived stem cell derived exosomes (ADSC-Exos) on angiogenesis after skin flap transplantation in rats. ADSCs were isolated and cultured by enzymatic digestion from voluntary donated adipose tissue of patients undergoing liposuction. The 3rd generation cells were observed under microscopy and identified by flow cytometry and oil red O staining at 14 days after induction of adipogenesis. After cells were identified as ADSCs, ADSC-Exos was extracted by density gradient centrifugation. And the morphology was observed by transmission electron microscopy, the surface marker proteins (CD63, TSG101) were detected by Western blot, and particle size distribution was measured by nanoparticle size tracking analyzer. Twenty male Sprague Dawley rats, weighing 250-300 g, were randomly divided into ADSC-Exos group and PBS group with 10 rats in each group. ADSC-Exos (ADSC-Exos group) and PBS (PBS group) were injected into the proximal, middle, and distal regions of the dorsal free flaps with an area of 9 cm×3 cm along the long axis in the two groups. The survival rate of the flap was measured on the 7th day, and then the flap tissue was harvested. The tissue morphology was observed by HE staining, and mean blood vessel density (MVD) was measured by CD31 immunohistochemical staining. ADSCs were identified by microscopy, flow cytometry, and adipogenic induction culture. ADSC-Exos was a round or elliptical membrane vesicle with clear edge and uniform size. It has high expression of CD63 and TSG101, and its size distribution was 30-200 nm, which was in accordance with the size range of Exos. The distal necrosis of the flaps in the ADSC-Exos group was milder than that in the PBS group. On the 7th day, the survival rate of the flaps in the ADSC-Exos group was 64.2%±11.5%, which was significantly higher than that in the PBS group (31.0%±6.6%; t=7.945, P=0.000); the skin appendages in the middle region of the flap in the ADSC-Exos group were more complete, the edema in the proximal region was lighter and the vasodilation was more extensive. MVD of the ADSC-Exos group was (103.3±27.0) /field, which was significantly higher than that of the PBS group [(45.3±16.2)/field; t=3.190, P=0.011]. ADSC-Exos can improve the blood supply of skin flaps by promoting the formation of neovascularization after skin flap transplantation, thereby improve the survival rate of skin flaps in rats.

Rip 1-dependent endothelial necroptosis participates in ischemia-reperfusion injury of mouse flap

BackgroundIschemia reperfusion injury plays an important role in free flap necrosis. However, the detailed mechanism is not clear, and effective methods for improving the survival rate of skin flap are still lacking. ObjectiveTo investigate the regulation and functional link between necroptosis and ischemia-reperfusion injury of mouse flap. MethodsWe established a mouse ischemia-reperfusion injury flap model and a cell Oxygen Glucose Deprivation (OGD) model intervened with Necrostatin-1. The mouse flap tissues were harvested in vivo for histological immunofluorescence analysis and western blotting analyses. The HUVECs cells with various treatments in vitro were assessed by using Transwell assay, tube formation assay, cell counting kit-8 analysis and flow cytometry. A Rip3-knockout cell line and a TNFR1-knockout cell line were generated from HUVEC cells using the CRISPR-Cas9 technology and were subsequently used to explore the related mechanisms. ResultsThe expression of p-Rip3 is positive in both mouse and cell culture models. When necroptosis is completely or partially inhibited in vivo, damaged tissues are repaired with better efficiency. The cells treated with Necrostatin-1 in vitro exhibit faster migration, proliferation and better tube formation. Deficiency of TNFR1 can block the necroptosis pathway by blocking the phosphorylation of Rip3 in HUVEC OGD/ROG model. Meanwhile, the levels of APJ, HIF-1α, and VEGF are reduced when necroptosis is inhibited by Necrostatin-1. ConclusionTNFR1 mediates Rip1/Rip3 in ischemia-reperfusion injury. Inhibition of necroptosis attenuates the ischemia-reperfusion injury of flap and may enhance hypoxic tolerance of HUVECs and vascular homeostasis through regulation of the HIF-1α signaling pathways.

Effect of Autologous Platelet-Rich Plasma Gel on Skin Flap Survival.

BackgroundSkin flap grafting is one of the most common tissue transplantations for wound repair and organ reconstruction. Thus, improving the survival rate of the transplanted skin flap is important. Platelet-rich plasma (PRP) is an autologous platelet concentrate obtained from whole blood. It has been widely used in repairing tissue defects. Considering that the PRP gel has similar biological characteristics, this study used PRP gel for skin flap transplantation.Material/MethodsPRP gel from Sprague-Dawley (SD) rats was prepared and the growth factor concentration was determined. A rat skin flap model was established to evaluate the survival rate of skin flap. Morphologic evaluation was also done.ResultsWe found that the PRP gel increased the survival rate of the skin flap. In addition, it reduces the inflammation response in skin flap transplantation and has better effects in terms of generating new soft tissue.ConclusionsThe effectiveness PRP gel in skin flap transplantation is satisfactory. The possible mechanisms by which PRP gel promotes the survival of the skin flap includes platelets, growth factors, immune activity factor, and fibrin. PRP could be a new clinical method for promoting skin flap survival.

Effects from transplantation of human amniotic mesenchymal stem cells on survival of random skin flap in rats

Objective To investigate the feasibility of human amniotic mesenchymal stem cells (hAMSCs) transplantation to improve the survival of ischemic ultra-long random skin flap vascularization, so as to promote the survival of skin flap. Methods The hAMSCs were isolated from human amnion, cultured in vitro, and identified by immunocytochemistry. The phenotype of hAMSCs was analyzed by flow cytometry. CellTracker™-CM-Dil was used to label before hAMSCs transplantation into skin flap. Twenty SD adult rats were selected and the 2 cm×8 cm ischemic ultra-long random skin flap models were constructed in the left and right sides of the rat back. The pedicles of flaps were on the lliac crest level. The flaps were divided into left group (injection with 0.5 ml LG-DMEM) and right group (0.5 ml 1×106/ml hAMSCs) after the flap was lifted. The survival rate of flap was observed 7 d after surgery. The blood perfusion values, namely blood perfusion unit at pedicle and in the middle, were monitored by laser Doppler flow monitor at the immediate time, 24 h, 48 h, 4 d and 7 d of the skin flap after surgery. The capillary density of the skin flap was observed through histological observation of the tissue (0.5 cm from adult and necrotic junction). The distribution and survival rate of CM-Dil labeled hAMSCs were observed by fluorescent microscope. Results In term of survival rate of the flap, left group was (50.6±2.2)%, and right group was (70.9±2.1)%. The survival rate of the flap in right group was greater than that of left group (P<0.05). Blood perfusion unit detected in the pedicle of left group at days 4 and 7 after surgery was higher than that of the right group (P<0.05). Blood perfusion unit in middle of flap of left group at 24 h, 48 h, 4 d and 7 d were lower than that of right group (P<0.05). The flap capillary density at 7 d after surgery were (8.8±1.2)/ mm2 in left group and (23.5±1.6)/mm2 in right group (P<0.05). The tissue of flap was made frozen section, and the fluorescence microscope showed there were CM-Dil labeled hAMSCs in skip flap in right group, which could manifest the survival and distribution of hAMSCs in skip flap. Conclusion The application of hAMSCs in the middle and distal parts of ultra-long random skin flap can significantly improve the survival rate of skin flap, and increase the density of microvascular reconstruction in the flap. Key words: Mesenchymal stem cell transplantation; Amnion; Surgical flaps

EFFECTS OF Tempol ON SURVIVAL OF RANDOM PATTERN SKIN FLAPS IN RATS

To study the effects of the new small molecular oxygen free radical scavenger Tempol on the survival and vasculogenesis of the long random pattern skin flap (LRPSF) and its mechanism. Eighty-four male Sprague Dawley rats were randomly divided into control and Tempol groups (42 rats in each group). LRPSF of 9 cm×3 cm in size were prepared on the backs of rats in two groups based on the Mcfarlane flap. Rats were administered with Tempol (100 mg/kg) in the Tempol group and with normal saline in the control group by intraperitoneal injection at 15 minutes before operation and at 1-7 day after operation. The rat and the skin flap survival conditions were observed after operation; the survival rate of skin flap was measured, and the vascular structure, vascular volume, and total length of blood vessels were analyzed with Micro-CT three-dimensional imaging after 7 days; HE staining was used to observe the structure of the skin flaps and inflammation, immumohistochemical staining to observe vascular endothelial growth factor (VEGF) expression; water-soluble tetrazolium-1 method was used to measure the content of superoxide dismutase (SOD) and malondialdehyde (MDA), and ELISA to detect the expressions of tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6) after 1, 3, and 7 days. All of rats survived after operation, without hemorrhage, edema, and infection. With the extension of time, necrosis occurred in the distal part of the skin flaps in 2 groups, but the necrosis degree of the Tempol group was lower than that of control group; meanwhile, the blood vessel distribution and continuity were better than those of control group. The skin flaps survival rate, vascular volume, and total length of blood vessels of Tempol group were significantly higher than those of control group after 7 days (P<0.05). The clearer skin flaps structure, lighter inflammation reaction and inflammation cell infiltration, and higher VEGF staining intensity were observed in the Tempol group than the control group after 7 days. There was no significant difference in SOD, MDA, and TNF-α, and IL-6 contents between the 2 groups at immediate after operation. SOD significantly increased, but MDA, TNF-α, and IL-6 contents significantly decreased in the Tempol group when compared with control group after 1, 3, and 7 days (P<0.05). Tempol can significantly promote the LRPSF survival rates, its mechanism is closely related to the promotion of vasculogenesis and reduction of oxidative stress and inflammation.