Romed Meirer

Comparison of the effectiveness of gene therapy with transforming growth factor-β or extracorporal shock wave therapy to reduce ischemic necrosis in an epigastric skin flap model in rats

The induction of neoangiogenesis by exogenous growth factors in failing skin flaps has recently yielded promising results. Gene transfer with virus vectors has been introduced as a highly capable route of administration for growth factors, such as vascular endothelial growth factor or fibroblast growth factor. Extracorporal shock waves (ESW) deliver energy by means of high amplitudes of sound to the target tissue and have been shown to induce angiogenesis. We compared the effectiveness of gene therapy with adenovirus‐mediated transforming growth factor‐β (TGF‐β) and ESW therapy to treat ischemically challenged epigastric skin flaps in a rat model. Thirty male Sprague‐Dawley rats were divided into three groups of 10 each with an 8 × 8 cm epigastric skin flap. Rats received either subdermal injections of adenovirus (Ad) encoding TGF‐β (108 pfu) or ESW treatment with 750 impulses at 0.15 mJ/mm2. The third group received no treatment and served as a control group. Flap viability was evaluated after 7 days and digital images of the epigastric flaps were taken and areas of necrotic zones relative to total flap surface area calculated. Histologic evaluation and increased angiogenesis were confirmed by CD31 immunohistochemistry. Overall, there was a significant increase in mean percent surviving area in the Ad‐TGF‐β group and the ESW group compared to the control group (ESW group: 97.7 ± 1.8% vs. Ad‐TGF‐β: 90.3 ± 4.0% and control group: 82.6 ± 4.3%; p < 0.05). Furthermore, in the ESW group mean percent surviving areas were significantly larger than in the Ad‐TGF‐β group (ESW group: 97.7 ± 1.8% vs. Ad‐TGF‐β: 90.3 ± 4.0%; p < 0.05). Flap vascularization was increased by Ad‐TGF‐β and ESW with numerous vessels, however, there was no significant difference between the two treatment groups. We conclude that treatment with ESW enhances epigastric skin flap survival significantly more than Ad‐TGF‐β treatment and thus represents a modality that is feasible, cost‐effective, and less invasive compared to gene therapy with growth factors to improve blood supply to ischemic tissue.

Medial Thigh Lift Free Flap for Autologous Breast Augmentation after Bariatric Surgery

Background: Massive weight loss following bariatric surgery frequently results in body contour deformities like ptotic and hypoplastic breasts, redundant abdominal tissue and loose skin especially in the medial thigh area.This redundant tissue can be used for breast augmentation in the case of hypertrophic ptotic breasts. Method: In 3 patients who underwent a vertical banded gastroplasty and consecutively lost more than 60% of their body weight, a breast augmentation with a transverse gracilis myocutaneous free flap was performed. Results: Bilateral myocutaneous gracilis free flap breast augmentation resulted in an esthetic, pleasing result, with additional correction of the redundant skin from the medial thigh region. Conclusion: Autologous breast augmentation with a simultaneous medial thigh lift can be performed safely, after successful weight loss following bariatric surgery.

Extracorporeal shock wave treatment in ischemic tissues: what is the appropriate number of shock wave impulses?

The dose-dependent effect of extracorporeal shock wave technology (ESWT) was evaluated using a murine skin flap model. Thirty-six Sprague-Dawley rats were divided into six groups (ESWT groups 1 through 5 and a control group). After surgery, shock wave impulses doses were administered: 200 (group 1), 500 (group 2), 1500 (group 3), 2500 (group 4), 5000 (group 5), and 0 (control group 6). Flap viability was evaluated on day 7. Overall, significantly smaller percentages of necrotic zones were observed in groups 2, 3, and 4 compared with groups 1, 5, and the control group ( P < 0.05). ESWT treatment with 200 impulses was found to be ineffective. ESWT treatment of 5000 impulses resulted in a significant increase in the percentage of necrosis compared with other ESWT groups ( P < 0.05). However, ESWT treatments between 500 and 2500 impulses at 0.11 mJ/mm (2) enhanced epigastric skin flap survival significantly.

A novel technique for peripheral nerve repair

Objective To evaluate a novel technique for the repair of neural deficits using a single fascicle to bridge an injury in the rat sciatic nerve.

Effect of chronic cyclosporine administration on peripheral nerve regeneration: a dose-response study.

An experimental study was conducted to investigate the effect of chronic cyclosporine A (CsA) administration with different doses on peripheral nerve regeneration. Forty adult male Lewis rats weighing 150 to 200 g were used. The right sciatic nerve was transected 1 cm distal to the sciatic notch, and a conventional end-to-end nerve coaptation was performed. According to the daily dose of subcutaneous CsA injections, animals were randomized into one control group and four experimental groups of 8 animals each (group I, control with no treatment; group II, 2 mg per kilogram CsA; group III, 4 mg per kilogram CsA; group IV, 8 mg per kilogram CsA; and group V, 16 mg per kilogram CsA). Daily injections of CsA were administered for 12 weeks by an investigator blinded to the different treatment groups. At 3, 6, and 12 weeks after nerve repair, motor recovery was evaluated by the toe spread test, and sensory recovery was measured using the pin-prick test and somatosensory evoked potentials (SEPs). Evaluations were performed by an investigator who was blinded to the treatment groups. At 12 weeks, sciatic nerve samples were harvested for histomorphometric analysis. Motor recovery was retarded regardless of CsA dose at each time point of evaluation. Sensory recovery was only delayed in the 16-mg-per-kilogram CsA treatment group at the 3 week follow-up. SEP results revealed significantly prolonged N2 and P1 latencies in all CsA treatments regardless of dose and time frame of evaluation compared with the control group (p < 0.05). Histomorphometric analysis demonstrated significantly reduced numbers of myelinated axons, reduced myelin sheath thickness, and reduced diameters in all CsA treatment groups compared with the control group (p < 0.05). Based on these findings in this experimental model of sciatic nerve, the authors conclude that CsA overall had direct deleterious effects on peripheral nerve regeneration as demonstrated by SEP, pin-prick test, toe spread test, and histomorphometric nerve analysis. These adverse effects seemed to be dose related for sensory recovery only at 3 and 6 weeks of CsA exposure after nerve repair. Motor recovery was affected negatively by short- and long-term CsA administration regardless of dose.

Preoperative shock wave therapy reduces ischemic necrosis in an epigastric skin flap model.

Extracorporeal shock wave therapy (ESWT) has recently been demonstrated to improve skin flap survival. In all these studies EWST was applied immediately after the surgical intervention. Thus, the purpose of this study was to determine the preoperative effect of ESWT as a noninvasive technique to precondition flap tissue in a rat epigastric skin flap model.EWST and control groups each contained 10 animals. ESWT was applied 7 days before the surgical intervention, whereas the control group received no treatment. Follow-up evaluation was performed on postoperative day 5. The mean area of flap necrosis, expressed as a percentage of the total flap area, was calculated. A significant reduction of the average flap necrosis area was observed in the ESWT group (27.2% ± 9.6%) compared with the control group (46.1% ± 7.9% (P < 0.05).In summary, this study indicates that preoperative ESWT may enhance skin flap survival in a rodent model.

Optimal Timing of Extracorporeal Shock Wave Treatment to Protect Ischemic Tissue

Enhancement of flap survival through extracorporeal shock wave treatment (ESWT) is a promising new technique; however, no attempt has been made to define the optimal time point and frequency of ESWT to optimize treatment with ESWT for ischemic indications. Twenty-eight male Wistar rats were randomized into 4 groups and an oversized, random-pattern flap was raised and reattached in place in each animal. ESWT was applied 7 days before (group E7) or immediately after the surgical intervention (group E0). The third group was treated with ESWT 7 days before and additionally immediately after the operation (group E7/0). The fourth group served as a control group and did not receive any ESWT (group C). Seven days after flap harvest the results of flap survival, perfusion, microvessel density, and vascular endothelial growth factor concentrations were assessed. Flap survival was significantly increased in all ESWT groups as compared with the control group. The groups (E7 and E0) that received ESWT pre- or postoperatively showed a significant increase in flap perfusion and microvessel density. Combined pre- and postoperative ESWT application (group E0/E7) did not demonstrate a cumulative effect in any evaluation. In this study, we were be able to prove the effectiveness of ESWT in the protection of ischemic tissue flaps. This study suggests that single postoperative application is the most efficacious protocol for clinical applications of ESWT in the treatment of ischemic tissue.

Muscle Prelamination with Urothelial Cell Cultures via Fibrin Glue in Rats

The purpose of the study was to transplant autologous cultured urothelial cells onto a muscle via fibrin glue as a delivery vehicle to create a vascularized, living matrix lined with urothelium that could subsequently be used for urinary reconstruction. Bladder tissue specimens from male Wistar rats (n = 32; 350--500 g) were harvested for urothelial tissue culture. After 8--10 days when the primary cultures became confluent, the cultured urothelial cells were injected underneath the rectus sheath onto the rectus muscle. As delivery vehicle we compared standard culture media and fibrin glue. At 1- and 4-week intervals following urothelial cell grafting, sections of the muscle were analyzed for urothelial graft take using Hematoxylin & Eosin and immunohistochemical staining. The histology demonstrated viable, multilayered clusters of urothelium cells on the muscle surface only in the group using the fibrin glue delivery vehicle. We conclude that a muscle can be successfully prelaminated with autologously cultured urothelial cells via fibrin glue and has therefore potential for urinary reconstructions.