Ischemia and reperfusion injury in superficial inferior epigastric artery-based vascularized lymph node flaps

Study on changes in serum irisin level in free-flap transplantation and the correlation of serum irisin level with flap blood flow

Background and aims

The beneficial effect of myokine irisin on ischemia-reperfusion of skin flaps has been rarely reported in clinical studies. This study was designed to determine whether irisin plays a protective role in flap transplantation and identify the factors affecting serum irisin levels.

Materials and methods

We analyzed the changes in serum irisin levels and flap blood flow before and after surgery in 40 patients who underwent skin-flap transplantation. Factors affecting serum irisin levels were analyzed by metabolic parameter measurements.

Results

Preoperative serum irisin levels were positively correlated with blood flow in the skin flap 7 days post-surgery. The increase in serum irisin levels in the first 3 days after surgery positively correlated with flap blood flow. A longer duration of high-intensity exercise, higher skeletal muscle content, lower body mass index, and waist-to-hip ratio were associated with higher irisin levels. Fasting blood glucose and glycosylated hemoglobin levels showed significant negative correlations with serum irisin levels. Several other indicators, including sex, were not associated with serum irisin levels.

Conclusions

Serum irisin levels benefit blood flow recovery during flap transplantation. Better outcomes may be achieved by adjusting the timing and intensity of the exercise and controlling the patient's body size.

Evaluation of effects of Tempol on testicular ischemia/reperfusion injury

AIM

Tempol, a synthetic antioxidant compound, has received significant attention for its potential therapeutic applications in recent years, especially against ischemia/reperfusion (I/R) injury. The aim of the present research was to assess the protective effects of Tempol on testicular I/R injury caused by testicular torsion and detorsion (T/D) in rats.

METHODS

The subjects were divided into five groups: sham, testicular T/D, testicular T/D with Tempol treatment at 50 and 100 mg/kg, and healthy rats treated with Tempol at 100 mg/kg. Testicular torsion was induced by rotating the left testicles for 2 h, followed by detorsion for 24 h. Testicular tissues were evaluated for gene expression, oxidative stress markers, and histopathology, epididymal sperms were stained and analyzed, and blood serum samples were collected to measure the testosterone hormone.

RESULTS

The results showed that testicular I/R caused a significant decrease in sperm velocity parameters, viability, and count, as well as an increase in abnormal sperms (p < 0.05). However, treatment with Tempol significantly improved these parameters (p < 0.05). Histopathological analysis revealed severe damage to the testicular tissues, but treatment with Tempol improved the structural integrity of the seminiferous tubules. Testicular I/R also resulted in increased oxidative stress index and decreased testosterone levels significantly (p < 0.05), but Tempol administration mitigated these effects significantly (p < 0.05). Furthermore, the expression of Bax and Bcl2, genes associated with apoptosis, were significantly altered by testicular I/R (p < 0.05), but Tempol prevented these changes significantly (p < 0.05).

CONCLUSION

These findings provide strong evidence that Tempol can effectively prevent testicular I/R injury.

Animal models in lymph node transfer surgery: A systematic review

BACKGROUND AND AIM

Lymph node transfer surgery (LNTS) is indicated in secondary lymphedema (LE) patients who do not respond to conservative therapy. Animal models are the spearhead of LE research and were used to pioneer most of the surgical interventions currently in practice. We conducted a systematic review of the literature to explore animal models dedicated to LNTS to compare different species, techniques, and outcomes.

METHODS

Four databases were searched: PubMed, Cumulative Index of Nursing and Allied Health Literature, Scopus, and Web of Science. We used the Preferred Reporting Items for Systematic Reviews and Meta-Analysis as our basis of organization.

RESULTS

Avascular lymph node graft (ALNG) and vascularized lymph node transfer (VLNT) effectively treated LE and lead to better outcomes than controls. Whole ALNGs are superior to fragmented ALNGs. Larger fragments are more likely to be reintegrated into the lymphatic system than small fragments. VLNT was superior to whole and fragmented ALNG. Increasing the number of VLNT resulted in better outcomes. Adipose-derived stem cells improved outcomes of VLNT; vascular endothelial growth factor C and D and platelet-rich plasma improved outcomes for ALNG. Cryopreservation of lymph nodes (LNs) did not affect outcomes for ALNG. The critical ischemia and venous occlusion time for LN flaps were 4-5 and 4 h, respectively. The critical time for reperfusion injury was 2 h. Some of the novel models included venous LNT, and cervical adipocutaneous flap to groin.

CONCLUSION

Current evidence from animals favors VLNT over other surgical interventions. Several pharmacological therapies significantly improved outcomes of ALNG and VLNT.

RELEVANCE TO PATIENTS

LE is a chronic condition affecting millions of patients worldwide. LNTS is becoming more popular as a LE treatment. Animal models have led the LE research for decades and developing new models for LE are essential for LE research. This systematic review aims to summarize the existing animal models dedicated to LNTS. We believe that this review is critical to guide researchers in the selection of the model that is best fit for their hypothesis-driven experiments.

Effects of citral on serum antioxidant status and liver genes expressions of paraoxonase 1 and nitric oxide synthase in a rat model of streptozotocin-induced diabetes mellitus

Background:

Citral (C₁₀H₁₆O) is the main ingredient of Cymbopogon citratus (lemongrass oil) and can reduce the side effects of oxidative stress. Diabetes caused by insulin deficiency induces oxidative stress in the liver.

Aims:

This study aimed to investigate the ameliorative effects of citral on selected oxidative parameters and the gene expression of paraoxonase 1 (PON1) and endothelial nitric oxide synthase (eNOS) in a rat model of streptozotocin (STZ)-induced diabetes mellitus.

Methods:

Forty rats were divided into four groups at random: control (C), control citral (CC), and two STZ-induced diabetic groups (diabetic (D) and citral diabetic (CD)). After diabetes confirmation (day 7), gavage treatment with citral (300 mg/kg body weight (BW)) was started in the CD and CC groups and continued for two weeks.

Results:

On day 21 of the study, following treatment with citral for 14 days, the serum levels of total antioxidant capacity (TAC), and PON1 in the CD group were significantly increased compared to those in the D group (P<0.05). While treatment with citral caused a significant decrease in the Malondialdehyde (MDA), and eNOS in the CD group compared to those of the D group (P<0.001). The expression rate of liver PON1 gene was considerably upregulated in the CD group compared to that in the D group (P<0.001); while the opposite was observed for eNOS gene expression. However, there was no significant difference between the CC and C groups in terms of all examined parameters (P>0.05).

Conclusion:

This study showed positive effects of citral on serum antioxidant status and liver gene expression of PON1 and eNOS in diabetic rats.

Lower Limb Lymphedema Patients Can Still Benefit from Supermicrosurgical Lymphaticovenous Anastomosis (LVA) after Vascularized Lymph Node Flap Transfer (VLNT) as Delayed Lymphatic Reconstruction-A Retrospective Cohort Study

Background: For lymphedema patients who received a vascularized lymph node flap transfer (VLNT) as their primary treatment, what are the treatment options when they seek further improvement? With recent publications supporting the use of lymphaticovenous anastomosis (LVA) for treating severe lymphedema, we examined whether LVA could benefit post-VLNT patients seeking further improvement. Methods: This retrospective cohort study enrolled eight lymphedema patients with nine lymphedematous limbs (one patient suffered from bilateral lower limb lymphedema) who had received VLNT as their primary surgery. Patients with previous LVA, liposuction, excisional therapy, or incomplete data were excluded. LVA was performed on nine lower lymphedematous limbs. Demographic data and intraoperative findings were recorded. Preoperative and postoperative limb volumes were measured with magnetic resonance volumetry. The primary outcome was the limb volume measured 6 months post-LVA. Results: The median duration of lymphedema before LVA was 10.5 (4.9–15.3) years. The median waiting time between VLNT and LVA was 41.4 (22.3–97.9) months. The median volume gained in the lymphedematous limb was 3836 (2505–4584) milliliters (mL). The median post-LVA follow-up period was 18 (6–30) months. Significant 6-month and 1-year post-LVA percentage volume reductions were found compared to pre-LVA volume (both p < 0.001). Conclusion: Based on the results from this study, the authors recommend the use of LVA as a secondary procedure for post-VLNT patients seeking further improvement.

A Review of CXCL1 in Cardiac Fibrosis

Chemokine C-X-C motif ligand-1 (CXCL1), principally expressed in neutrophils, macrophages and epithelial cells, is a valid pro-inflammatory factor which performs an important role in mediating the infiltration of neutrophils and monocytes/macrophages. Elevated serum level of CXCL1 is considered a pro-inflammatory reaction by the organism. CXCL1 is also related to diverse organs fibrosis according to relevant studies. A growing body of evidence suggests that CXCL1 promotes the process of cardiac remodeling and fibrosis. Here, we review structure and physiological functions of CXCL1 and recent progress on the effects and mechanisms of CXCL1 in cardiac fibrosis. In addition, we explore the role of CXCL1 in the fibrosis of other organs. Besides, we probe the possibility that CXCL1 can be a therapeutic target for the treatment of cardiac fibrosis in cardiovascular diseases.

From Bench to Bedside: The Role of a Multidisciplinary Approach to Treating Patients with Lymphedema

Background: Lymphedema is a condition characterized by dysfunction of the lymphatic system resulting in chronic, progressive soft tissue edema that can negatively impact individuals' function, self-image, and quality of life. Understanding of the disease process has evolved significantly in the past two decades with advances in diagnostic modalities and surgical techniques revolutionizing prior treatment algorithms. Methods and Results: We reviewed our current approach at the University of Southern California to improving outcomes in lymphedema treatment. Given the complexity of this medical condition, patients are best served by a multidisciplinary approach. At our institution, this involves a collaborative effort between bench researchers, lymphatic therapists, medical physicians, and lymphedema surgeons. Basic science and translational research provide further understanding into the underlying mechanisms of lymphangiogenesis and the possibility for potential therapeutic interventions. Our surgical algorithms require patients to undergo a thorough diagnostic evaluation and consultation with certified lymphatic therapists prior to undergoing either physiologic or debulking operations. Patients are followed clinically following any interventions. Further community outreach and education is carried out in order to improve upon early diagnosis and symptom recognition. Conclusions: Optimizing lymphedema care requires a collaborative interplay between researchers, physicians, and therapists. Additionally, patient and provider education on early disease recognition and treatment options is an equally critical aspect of improving patient outcomes.

GRK2 deletion improves the function of skin flap following ischemia-reperfusion injury by regulating Drp1

Skin flap ischemia-reperfusion (IR) injury is the key factor to the success rate of skin transplantation, the molecular mechanism of flap IR injury needs to be continuously explored to provide new ideas for its clinical treatment. G protein-coupled receptor kinase 2 (GRK2) was reported to be involved in regulating mitochondrial function, and mitochondria were essential in the process of flap IR. Thus, we aimed to investigate the function of GRK2 in flap ischemia-reperfusion injury and further explore the underlying mechanism. Sixty male C57BL/6 mice were randomly divided into four groups: sham, IR+sh-NC, IR+sh-GRK2 and IR+sh-GRK2+ dynamin-related GTPase 1 (Drp1). Flap function and mitochondrial function were determined after ischemia for 3 hours and reperfusion for 72 hours. Comparing with sham group, GRK2 was increased in flap after IR injury. Loss of GRK2 inhibited cell apoptosis and promoted cell proliferation of flap after IR injury. And deficiency of GRK2 promoted mitochondrial function in flap after IR injury. IR injury up-regulated Drp1 expression in flap, while sh-GRK2 down-regulated Drp1 expression. Furthermore, overexpression of Drp1 removed the protective effect of sh-GRK2. In conclusion, our study revealed that GRK2 deletion improved flap function and mitochondrial function by inhibiting Drp1 expression, which may provide a new insight for the clinical treatment of flap ischemia-reperfusion injury.

Short-term molecular and cellular effects of ischemia/reperfusion on vascularized lymph node flaps in rats

Vascularized lymph node (VLN) transfer is an emerging strategy to re-establish lymphatic drainage in chronic lymphedema. However, the biological processes underlying lymph node integration remain elusive. This study introduces an experimental approach facilitating the analysis of short-term molecular and cellular effects of ischemia/reperfusion on VLN flaps. Lymph node flaps were dissected pedicled on the lateral thoracic vessels in 44 Lewis rats. VLN flaps were exposed to 45 or 120 minutes ischemia by in situ clamping of the vascular pedicle with subsequent reperfusion for 24 hours. Flaps not exposed to ischemia/reperfusion served as controls. Lymph nodes and the perinodal adipose tissue were separately analyzed by Western blot for the expression of lymphangiogenic and angiogenic growth factors. Moreover, morphology, microvessel density, proliferation, apoptosis and immune cell infiltration of VLN flaps were further assessed by histology and immunohistochemistry. Ischemia for 120 minutes was associated with a markedly reduced cellularity of lymph nodes but not of the perinodal adipose tissue. In line with this, ischemic lymph nodes exhibited a significantly lower microvessel density and an increased expression of VEGF-D and VEGF-A. However, VEGF-C expression was not upregulated. In contrast, analyses of the perinodal adipose tissue revealed a more subtle decrease of microvessel density, while only the expression of VEGF-D was increased. Moreover, after 120 minutes ischemia, lymph nodes but not the perinodal adipose tissue exhibited significantly higher numbers of proliferating and apoptotic cells as well as infiltrated macrophages and neutrophilic granulocytes compared with non-ischemic flaps. Taken together, lymph nodes of VLN flaps are highly susceptible to ischemia/reperfusion injury. In contrast, the perinodal adipose tissue is less prone to ischemia/reperfusion injury.