Gene therapy using hepatocyte growth factor expressing adenovirus improves skin flap survival in a rat model

VEGF and Other Gene Therapies Improve Flap Survival-A Systematic Review and Meta-Analysis of Preclinical Studies

Surgical flaps are basic tools in reconstructive surgery. Their use may be limited by ischemia and necrosis. Few therapies address or prevent them. Genetic therapy could improve flap outcomes, but primary studies in this field present conflicting results. This systematic review and meta-analysis aimed to appraise the efficacy of external gene delivery to the flap for its survival in preclinical models. This review was registered with PROSPERO (CRD42022359982). PubMed, Embase, Web of Science, and Scopus were searched to identify studies using animal models reporting flap survival outcomes following any genetic modifications. Random-effects meta-analysis was used to calculate mean differences in flap survival with accompanying 95% CI. The risk of bias was assessed using the SYRCLE tool. Subgroup and sensitivity analyses were performed to ascertain the robustness of primary analyses, and the evidence was assessed using the GRADE approach. The initial search yielded 690 articles; 51 were eventually included, 36 of which with 1576 rats were meta-analyzed. VEGF gene delivery to different flap types significantly improved flap survival area by 15.66% (95% CI 11.80-19.52). Other interventions had smaller or less precise effects: PDGF-13.44% (95% CI 3.53-23.35); VEGF + FGF-8.64% (95% CI 6.94-10.34); HGF-5.61% (95% CI 0.43-10.78); FGF 3.84% (95% CI 1.13-6.55). Despite considerable heterogeneity, moderate risk of bias, and low quality of evidence, the efficacy of VEGF gene therapy remained significant in all sensitivity analyses. Preclinical data indicate that gene therapy is effective for increasing flap survival, but further animal studies are required for successful clinical translation.

Nanomaterials for the delivery of bioactive factors to enhance angiogenesis of dermal substitutes during wound healing

Dermal substitutes provide a template for dermal regeneration and reconstruction. They constitutes an ideal clinical treatment for deep skin defects. However, rapid vascularization remains as a major hurdle to the development and application of dermal substitutes. Several bioactive factors play an important regulatory role in the process of angiogenesis and an understanding of the mechanism of achieving their effective delivery and sustained function is vital. Nanomaterials have great potential for tissue engineering. Effective delivery of bioactive factors (including growth factors, peptides and nucleic acids) by nanomaterials is of increasing research interest. This paper discusses the process of dermal substitute angiogenesis and the roles of related bioactive factors in this process. The application of nanomaterials for the delivery of bioactive factors to enhance angiogenesis and accelerate wound healing is also reviewed. We focus on new systems and approaches for delivering bioactive factors for enhancing angiogenesis in dermal substitutes.

Efficacy of Combined in-vivo Electroporation-Mediated Gene Transfer of VEGF, HGF, and IL-10 on Skin Flap Survival, Monitored by Label-Free Optical Imaging: A Feasibility Study

Preventing surgical flaps necrosis remains challenging. Laser Doppler imaging and ultrasound can monitor blood flow in flap regions, but they do not directly measure the cellular response to ischemia. The study aimed to investigate the efficacy of synergistic in-vivo electroporation-mediated gene transfer of interleukin 10 (IL-10) with either hepatocyte growth factor (HGF) or vascular endothelial growth factor (VEGF) on the survival of a modified McFarlane flap, and to evaluate the effect of the treatment on cell metabolism, using label-free fluorescence lifetime imaging. Fifteen male Wistar rats (290–320 g) were randomly divided in three groups: group-A (control group) underwent surgery and received no gene transfer. Group-B received electroporation mediated hIL-10 gene delivery 24 h before and VEGF gene delivery 24 h after surgery. Group-C received electroporation mediated hIL-10 gene delivery 24 h before and hHGF gene delivery 24 h after surgery. The animals were assessed clinically and histologically. In addition, label-free fluorescence lifetime imaging was performed on the flap. Synergistic electroporation mediated gene delivery significantly decreased flap necrosis (P = 0.0079) and increased mean vessel density (P = 0.0079) in treatment groups B and C compared to control group-A. NADH fluorescence lifetime analysis indicated an increase in oxidative phosphorylation in the epidermis of the group-B (P = 0.039) relative to controls. These findings suggested synergistic in-vivo electroporation-mediated gene transfer as a promising therapeutic approach to enhance viability and vascularity of skin flap. Furthermore, the study showed that combinational gene therapy promoted an increase in tissue perfusion and a relative increase in oxidative metabolism within the epithelium.

Improvement of Flap Necrosis in a Rat Random Skin Flap Model by In Vivo Electroporation-Mediated HGF Gene Transfer

BACKGROUND

Despite great understanding of underlying mechanisms for flap necrosis and advances in surgical techniques, flap necrosis remains a critical issue. In the present study, the authors investigated the efficacy of electroporation-mediated hepatocyte growth factor (HGF) gene delivery to random dorsal skin flaps (McFarlane) to accelerate wound healing and reduce flap necrosis.

METHODS

Fifteen male Wistar rats (290 to 320 g) were divided randomly into three groups. Group a, the control group (n = 5), underwent surgery and received no gene transfer. Group b received electroporation-mediated HGF gene delivery 24 hours after surgery as a treatment. Group c received electroporation-mediated HGF gene delivery 24 hours before surgery as prophylaxis (n = 5). Planimetry, laser Doppler imaging, and immunohistochemistry were used to assess the efficacy of HGF gene therapy among the groups.

RESULTS

Electroporation-mediated HGF gene delivery significantly decreased flap necrosis percentage compared with the control group in prophylactic and treatment groups (p = 0.0317 and p = 0.0079, respectively) and significantly increased cutaneous perfusion compared with the control group (p = 0.0317 and p = 0.0159, respectively). Moreover, Spearman rank correlation showed a significant negative correlation between flap necrosis percentage and laser index (p = 0.0213 and r = -0.5964, respectively). Furthermore, significantly higher mean CD31 vessel density was detected in treatment and prophylactic groups (p = 0.0079 and p = 0.0159, respectively). In addition, quantitative image analysis revealed significantly higher HGF protein expression in groups b and c (p = 0.0079 and p = 0.0079, respectively).

CONCLUSION

These findings suggested in vivo electroporation-mediated HGF gene delivery enhanced viability and vascularity of the ischemic skin flap.

The Effect of Red Ginseng Extract Intake on Ischemic Flaps

Red ginseng is well known for its angiogenic effects and its effect of increasing expression of vascular endothelial growth factors (VEGFs), but little experimental evidence has been published. In this study, we examined the effect of red ginseng using an ischemic flap model. Twenty male Sprague-Dawley rats were divided into two groups of 10. One group drank red ginseng solution from 7 days prior to surgery to 7 days after, whereas the other group drank distilled water. We created a local flap on the back of each rat. We analyzed the surviving area of the flap for 10 days after surgery and measured the blood flow of the flap. Ten days after the operation, CD31-positive vessels and VEGF expression were examined by immunohistochemistry. The percentages of surviving areas of the flap were 76 ± 3% for the experimental group and 39 ± 5% for the control group (P = 0.0002). Blood flow in the experimental group increased for 10 days after the surgery. The number of newly generated capillaries in the experimental group was 14.0 ± 3.5, which was significantly higher than 5.7 ± 1.9 in the control group. The expression of VEGF in the experimental group was significantly higher than in the control group (p = 0.0003). Administration of red ginseng extract increases the survival of ischemic flaps via angiogenesis and elevated blood flow. Further clinical studies are warranted to apply the effect shown in this current investigation to various ischemic conditions.

Improved viability of random pattern skin flaps with the use of bone marrow mesenchymal-derived stem cells and chicken embryo extract

OBJECTIVES

Covering tissue defects using skin flaps is a basic surgical strategy for plastic and reconstructive surgery. The aim of this study was to evaluate the effects of chicken embryo extract (CEE) and bone marrow derived mesenchymal stem cells (BM-MSCs) on random skin flap survival (RSF) in rats. Using chicken embryo extract can be an ideal environment for the growth and proliferation of transplanted cells.

MATERIALS AND METHODS

Forty albino male Wistar rats were divided into 4 groups; each group consisted of 10 rats. BM-MSCs and CEE were transplanted into subcutaneous tissue in the area, where the flap would be examined. On the 7(th) postoperative day, the survival areas of the flaps were measured by using digital imaging with software assistance, and tissue was collected for evaluation.

RESULTS

Survival area was 19.54±2 in the CEE group and 17.90±2 in the CEE/BM-MSC group when compared to the rates of the total skin flaps, which were significantly higher than the control group (13.47±2) (P<0.05). The biomechanical assessment showed a slight difference, although there was no statistically significant difference between the experimental groups and the control group (P>0.05).

CONCLUSION

The findings from this study demonstrated that in operative treatment with BM-MSCs and CEE transplantation could promote flap survival, but the biomechanical parameters were not contrasted with a saline injection.