Novel Injury Site Targeted Fusion Protein Comprising Annexin V and Kunitz Inhibitor Domains Ameliorates Ischemia-Reperfusion Injury and Promotes Survival of Ischemic Rat Abdominal Skin Flaps

Annexin A5 suppression promotes the progression of cervical cancer

BACKGROUND

Cervical cancer is a common malignant gynecological disease that threatens the health of women all over the world. The abnormal expression of Annexin A5 (ANXA5) is closely related to the biological behavior of various malignant tumors, however, the relationship between ANXA5 and cervical cancer is still unclear. Therefore, the effects of low expression of ANXA5 on the proliferation, apoptosis, migration and invasion of cervical cancer cells (HeLa) and its related mechanism were explored.

METHODS

The cells were divided into three groups: ANXA5-si group, negative control group and blank group. RNA interference was used to suppress ANXA5 expression. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, colony formation assay, flow cytometry and propidium iodide (PI) staining, wound healing assay and transwell assay were employed to detect cell proliferation, apoptosis, migration and invasion respectively. Meanwhile, gene expression was detected by qPCR and Western blotting.

RESULTS

ANXA5 suppression lead to the increase of proliferation, migration, invasion and the decrease of apoptosis of cervical cancer HeLa cells. Furthermore, the expression of both pPI3K and pAkt increased.

CONCLUSION

ANXA5 might inhibit Hela cells proliferation and metastasis by regulating PI3K/Akt signal pathway.

Extracorporeal Perfusion in Vascularized Composite Allotransplantation: Current Concepts and Future Prospects

Severe injuries of the face and limbs remain a major challenge in today's reconstructive surgery. Vascularized composite allotransplantation (VCA) has emerged as a promising approach to restore these defects. Yet, there are major obstacles preventing VCA from broad clinical application. Two key restrictions are (1) the graft's limited possible ischemia time, keeping the potential donor radius extremely small, and (2) the graft's immunogenicity, making extensive lifelong monitoring and immunosuppressive treatment mandatory. Machine perfusion systems have demonstrated clinical success addressing these issues in solid organ transplantation by extending possible ischemia times and decreasing immunogenicity. Despite many recent promising preclinical trials, machine perfusion has not yet been utilized in clinical VCA. This review presents latest perfusion strategies in clinical solid organ transplantation and experimental VCA in light of the specific requirements by the vascularized composite allograft's unique tissue composition. It discusses optimal settings for temperature, oxygenation, and flow types, as well as perfusion solutions and the most promising additives. Moreover, it highlights the implications for the utility of VCA as therapeutic measure in plastic surgery, if machine perfusion can be successfully introduced in a clinical setting.

Extrapolating novel techniques utilised in solid organ transplantation to the microsurgical and vascularised composite allograft arena

Ischemia reperfusion injury (IRI) is characterised initially by restriction of oxygenated blood flow to an organ bed, resulting in tissue hypoxia and ischaemic injury, followed by further 'reperfusion' injury upon restoration of perfusion, with an influx of oxygen, inflammatory cells and generation of free radicals. The culmination is a complex interplay between cellular and biochemical processes involved in inflammation and coagulation, exhibited as the 'no re-flow' phenomenon. Under ideal circumstances, autologous free tissue transfer is performed with short ischemic times. However, there are certain clinical scenarios where the ischaemic period can be prolonged due to technical and non-technical factors. IRI is inevitable and can be possibly more pronounced in such cases. In these cases, there may be a role for plastic surgeons to adopt some of the anti-ischaemia reperfusion injury (IRI) practices used in solid organ transplantation (SOT). Knowledge of the current trends in SOT IRI reduction should be discussed by plastic surgeons to assess whether certain facets can be extrapolated into the plastic and reconstructive armamentarium. These can be applicable to more challenging microsurgical cases, including composite free tissue transfer. Three important aspects are discussed further in this editorial: (1) cold flushing, (2) machine perfusion and pharmacological manipulation. Ongoing research will need to study the impact these potential interventions will have on the acute complications but also in which subset of patients they would be most beneficial. This area is novel and exciting but cautious implementation is advised with careful scrutiny of future data.

Comparison of various methods to analyse toxic effects in human skin explants: Rediscovery of TTC assay

Skin explants are a suitable model which can replace dermatological experiments on animals or human volunteers. In this study, we searched for a fast, cheap and reproducible method for screening skin explant viability after treatment with UVA radiation or/and chemical agents. We compared frequently used methods: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), neutral red (NR) and lactate dehydrogenase (LDH) activity assay with a rarely used 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) assay for the evaluation of UVA radiation and/or chlorpromazine and 8-methoxypsoralen effect as model agents. Histological analysis of skin explants was also performed by a simple haematoxylin-eosin method. Only the TTC assay was able to show the toxicity of model agents in a dose- and concentration-dependent manner. LDH assay was partially able to demonstrate results comparable to the TTC method, however, the agents' effect was less pronounced. The MTT and NR assays completely failed in the evaluation. Haematoxylin-eosin staining showed discrete structural changes in samples treated with UVA alone and CPZ+UVA, but only after 48h. Therefore, the method is not useful for screening of toxic or phototoxic effects either. In conclusion, the TTC assay was the most suitable for the evaluation of toxicity or phototoxicity in ex vivo skin.

The rat groin flap model redesigned for evaluating treatment effects on ischemia-reperfusion injury

BACKGROUND

Although there is a wide application of the rat extended groin flap (epigastric skin flap) in studying different clinical issues, inconsistency arises between studies because many parameters of the extended groin flap have not been well defined.

MATERIALS AND METHODS

The flap is based on the superficial inferior epigastric vessels, which give into a lateral and a medial branch distally. Herein, three steps were taken to redesign this model: First, the ventral vascular anatomy was visualized through an imaging study to determine the flap borders. Second, different ischemic durations were induced on five groups of Lewis rats (n = 5 in each group) by clamping the femoral artery; group 1 (sham group) received no ischemic insult after elevation and was immediately repositioned, and groups 2, 3, 4, and 5 received 12-, 14-, 16-, and 18-hour ischemia, respectively. Percentage of necrosis area was measured after 5 days. Third, the redesigned groin flap model was tested with the ischemic postconditioning for validation.

RESULTS

The flap borders were determined such that both branches of the superficial inferior epigastric vessels were always included to ensure blood supply consistency. As the 14-hour ischemia induced the least variation in necrotic area on rats, it was chosen for further studies. In addition, ischemic postconditioning after 14-hr ischemia resulted in significant reduction of necrosis in this model.

CONCLUSIONS

We have redesigned the extended groin flap model with better-defined borders and consistent vascular anatomy. The ischemia duration was calibrated with predictable necrosis pattern and the practicality was demonstrated. With this model, precise assessment of treatment efficacies on ischemia-reperfusion injury could be achieved in future studies.