Pre- and postconditioning of ischemic musculocutaneous tissue with erythropoietin

Mit dieser Studie wurden die Gewebe-protektiven Effekte verschiedener Prä- und Postkonditionierungsschemata mit Erythropoetin in Mäusen evaluiert. Randomisiert perfundierte Hautmuskellappen, die akuter persistierender Ischämie ausgesetzt sind, wurden gehoben und in dorsale Rückenhautkammern eingebracht. Wiederholte intravitale Epifluoreszenzmikroskopien zur Evaluation von Nekrose, Mikrozirkulation und Angiogenese wurden zusammen mit Hämatokritmessungen über den Zeitraum von 10 Tagen nach Lappenhebung vorgenommen.With the present study we evaluated the tissue-protective effects of different erythropoietin pre- and postconditioning regimes in mice. Random pattern musculocutaneous flaps undergoing acute persistent ischemia were elevated and mounted into dorsal skinfold chambers. Repetitive intravital epifluorescence microscopies were performed assessing flap necrosis, microcirculation, and angiogenesis, together with hematocrit measurements for 10 days after flap elevation

Implant-Based Breast Reconstruction after Mastectomy, from the Subpectoral to the Prepectoral Approach: An Evidence-Based Change of Mind?

Over the last years, prepectoral implant-based breast reconstruction has undergone a renaissance due to several technical advancements regarding mastectomy techniques and surgical approaches for the placement and soft tissue coverage of silicone implants. Initially abandoned due to the high incidence of complications, such as capsular contraction, implant extrusion, and poor aesthetic outcome, the effective prevention of these types of complications led to the prepectoral technique coming back in style for the ease of implant placement and the conservation of the pectoralis muscle function. Additional advantages such as a decrease of postoperative pain, animation deformity, and operative time contribute to the steady gain in popularity. This review aims to summarize the factors influencing the trend towards prepectoral implant-based breast reconstruction and to discuss the challenges and prospects related to this operative approach

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

Bromelain Protects Critically Perfused Musculocutaneous Flap Tissue from Necrosis

Bromelain has previously been shown to prevent ischemia-induced necrosis in different types of tissues. In the present study, we, therefore, evaluated for the first time, the tissue-protective effects of bromelain in musculocutaneous flaps in mice. Adult C57BL/6N mice were randomly assigned to a bromelain treatment group and a control group. The animals were treated daily with intraperitoneal injections of 20 mg/kg bromelain or saline (control), starting 1 h before the flap elevation throughout a 10-day observation period. The random-pattern musculocutaneous flaps were raised on the backs of the animals and mounted into a dorsal skinfold chamber. Angiogenesis, nutritive blood perfusion and flap necrosis were quantitatively analyzed by means of repeated intravital fluorescence microscopy over 10 days after surgery. After the last microscopy, the flaps were harvested for additional histological and immunohistochemical analyses. Bromelain reduced necrosis of the critically perfused flap tissue by ~25%. The bromelain-treated flaps also exhibited a significantly higher functional microvessel density and an elevated formation of newly devel oped microvessels in the transition zone between the vital and necrotic tissues when compared to the controls. Immunohistochemical analyses demonstrated a markedly lower invasion of the myeloperoxidase-positive neutrophilic granulocytes and a significantly reduced number of cleaved caspase 3-positive apoptotic cells in the transition zone of bromelain-treated musculocutaneous flaps. These findings indicate that bromelain prevents flap necrosis by maintaining nutritive tissue perfusion and by suppressing ischemia-induced inflammation and apoptosis. Hence, bromelain may represent a promising compound to prevent ischemia-induced flap necrosis in clinical practice

Microvascular Fragments Protect Ischemic Musculocutaneous Flap Tissue from Necrosis by Improving Nutritive Tissue Perfusion and Suppressing Apoptosis

Microvascular fragments (MVF) derived from enzymatically digested adipose tissue are functional vessel segments that have been shown to increase the survival rate of surgical flaps. However, the underlying mechanisms have not been clarified so far. To achieve this, we raised random-pattern musculocutaneous flaps on the back of wild-type mice and mounted them into dorsal skinfold chambers. The flaps were injected with MVF that were freshly isolated from green fluorescent protein-positive (GFP+ ) donor mice or saline solution (control). On days 1, 3, 5, 7, and 10 after surgery, intravital fluorescence microscopy was performed for the quantitative assessment of angiogenesis, nutritive blood perfusion, and flap necrosis. Subsequently, the flaps were analyzed by histology and immunohistochemistry. The injection of MVF reduced necrosis of the ischemic flap tissue by ~20%. When compared to controls, MVF-injected flaps also displayed a significantly higher functional capillary density and number of newly formed microvessels in the transition zone, where vital tissue bordered on necrotic tissue. Immunohistochemical analyses revealed a markedly lower number of cleaved caspase-3+ apoptotic cells in the transition zone of MVF-injected flaps and a significantly increased number of CD31+ microvessels in both the flaps’ base and transition zone. Up to ~10% of these microvessels were GFP+ , proving their origin from injected MVF. These findings demonstrate that MVF reduce flap necrosis by increasing angiogenesis, improving nutritive tissue perfusion, and suppressing apoptosis. Hence, the injection of MVF may represent a promising strategy to reduce ischemia-induced flap necrosis in future clinical practice

Improved Vascularization and Survival of White Compared to Brown Adipose Tissue Grafts in the Dorsal Skinfold Chamber

Fat grafting is a frequently applied procedure in plastic surgery for volume reconstruction. Moreover, the transplantation of white adipose tissue (WAT) and brown adipose tissue (BAT) in creasingly gains interest in preclinical research for the treatment of obesity-related metabolic defects. Therefore, we herein directly compared the vascularization capacity and survival of WAT and BAT grafts. For this purpose, size-matched grafts isolated from the inguinal WAT pad and the interscapu lar BAT depot of C57BL/6N donor mice were syngeneically transplanted into the dorsal skinfold chamber of recipient animals. The vascularization and survival of the grafts were analyzed by means of intravital fluorescence microscopy, histology, and immunohistochemistry over an observation period of 14 days. WAT grafts showed an identical microvascular architecture and functional mi crovessel density as native WAT. In contrast, BAT grafts developed an erratic microvasculature with a significantly lower functional microvessel density when compared to native BAT. Accordingly, they also contained a markedly lower number of CD31-positive microvessels, which was associated with a massive loss of perilipin-positive adipocytes. These findings indicate that in contrast to WAT grafts, BAT grafts exhibit an impaired vascularization capacity and survival, which may be due to their higher metabolic demand. Hence, future studies should focus on the establishment of strategies to improve the engraftment of transplanted BAT

Co-transplantation of pancreatic islets and microvascular fragments effectively restores normoglycemia in diabetic mice

Insufficient revascularization of pancreatic islets is one of the major obstacles impairing the success of islet transplantation. To overcome this problem, we introduce in the present study a straightforward strategy to accelerate the engraftment of isolated islets. For this purpose, we co-transplanted 250 islets and 20,000 adipose tissue-derived microvascular fragments (MVF) from donor mice under the kidney capsule as well as 500 or 1000 islets with 40,000 MVF into the subcutaneous space of diabetic mice. We found that the co-transplantation of islets and MVF markedly accelerates the restoration of normoglycemia in diabetic recipients compared with the transplantation of islets alone. In fact, the transplantation of 250 islets with 20,000 MVF under the kidney capsule reversed diabetes in 88% of mice and the subcutaneous transplantation of 500 or 1000 islets with 40,000 MVF restored normoglycemia in 100% of mice. Moreover, diabetic mice receiving islets and MVF exhibited plasma insulin levels similar to nondiabetic control animals. Additional immunohistochemical analyses of the grafts revealed a significantly higher number of islet cells and microvessels in the co-transplantation groups. These findings demonstrate that the co-transplantation of islets and MVF is a promising strategy to improve the success rates of islet transplantation, which could be easily implemented into future clinical practice

First-in-human Use of a Microsurgical Robotic System for Central Lymphatic Reconstruction

Advances in the development of robotic systems have recently enabled the use of robotic technology in reconstructive lymphatic surgery. Although the advantages of microsurgical robots must be weighed carefully against the costs, their use may allow for smaller surgical approaches and easier access to anatomically deeper structures or even smaller vessels. We report on a case of a patient with central lymphatic dilation causing abdominal pain and severely reduced physical capacity. Sonography-assisted intranodal injection of indocyanine green allowed for localization of the lymphatic cyst and anastomosis with the left ovarian vein, applying robotic-assisted microsurgery for the first time on the central lymphatic system. Following the successful reconstruction of lymphatic drainage and decompression of the cyst, the patient reported a complete regression of her preoperative symptoms. From a surgical point of view, the Symani Surgical System improved precision and allowed significantly smaller surgical access. Considering the high morbidity and rarity of pathologies of the central lymphatic system, central lymphatic surgery is to date rarely performed. With improved precision and significantly smaller surgical access, robotic-assisted microsurgery has great potential to expand the treatment options for central lymphatic lesions

The Parkinson's disease-linked Leucine-rich repeat kinase 2 (LRRK2) is required for insulin-stimulated translocation of GLUT4

Mutations within Leucine-rich repeat kinase 2 (LRRK2) are associated with late-onset Parkinson's disease. The physiological function of LRRK2 and molecular mechanism underlying the pathogenic role of LRRK2 mutations remain uncertain. Here, we investigated the role of LRRK2 in intracellular signal transduction. We find that deficiency of Lrrk2 in rodents affects insulin-dependent translocation of glucose transporter type 4 (GLUT4). This deficit is restored during aging by prolonged insulin-dependent activation of protein kinase B (PKB, Akt) and Akt substrate of 160 kDa (AS160), and is compensated by elevated basal expression of GLUT4 on the cell surface. Furthermore, we find a crucial role of Rab10 phosphorylation by LRRK2 for efficient insulin signal transduction. Translating our findings into human cell lines, we find comparable molecular alterations in fibroblasts from Parkinson's patients with the known pathogenic G2019S LRRK2 mutation. Our results highlight the role of LRRK2 in insulin-dependent signalling with potential therapeutic implications