Evaluation of angiogenesis, epithelialisation and microcirculation after application of polyhexanide, chitosan and sodium chloride in rodents.

The purpose of this study was to investigate the effect of polyhexanide and a new developed chitin-based wound dressing on skin microcirculation, epithelialisation and angiogenesis. A full-thickness dermal layer extending to the underlying cartilage was excised on the dorsal side of hairless mice (n = 27; 2·3 ± 0·3 mm2 ). A polyhexanide ointment, a chitosan solution and a sodium chloride group as control were analysed using intravital fluorescence microscopy. Angiogenesis, epithelialisation and microcirculatory standard parameters were measured over a time period of 20 days. The non-perfused area is regarded as a parameter for angiogenesis and showed the following results: on days 12, 16 and 20, the sodium chloride group was significantly superior to chitosan solution (P < 0·05) and, on days 8, 12, 16 and 20, the polyhexanide group was superior to chitosan solution (P < 0·05). The epithelialisation was measured significantly faster in the polyhexanide and control group on day 8 versus chitosan solution. Whereas polyhexanide and sodium chloride were nearly completely epithelialised, treatment with chitosan solution showed still an open wound of 11% of the initial wound size. Altogether, we could demonstrate the advantageous effects of a polyhexanide ointment on microcirculation, angiogenesis and epithelialisation. Chitosan solution appears to inhibit angiogenesis and delays epithelialisation. Further studies in different models would be worthwhile to confirm these results.

Microsurgical Reconstruction of Extensive Oncological Scalp Defects.

Although most small to medium defects of the scalp can be covered by local flaps, large defects or complicating factors, such as a history of radiotherapy, often require a microsurgical reconstruction. Several factors need to be considered in such procedures. A sufficient preoperative planning is based on adequate imaging of the malignancy and a multi-disciplinary concept. Several flaps are available for such reconstructions, of which the latissimus dorsi and anterior-lateral thigh flaps are the most commonly used ones. In very large defects, combined flaps, such as a parascapular/latissimus dorsi flaps, can be highly useful or necessary. The most commonly used recipient vessels for microsurgical scalp reconstructions are the superficial temporal vessels, but various other feasible choices exist. If the concomitant veins are not sufficient, the jugular veins represent a safe back-up alternative but require a vessel interposition or long pedicle. Post-operative care and patient positioning can be difficult in these patients but can be facilitated by various devices. Overall, microsurgical reconstruction of large scalp defects is a feasible undertaking if the mentioned key factors are taken into account.

New model for long-term investigations of cutaneous microcirculatory and inflammatory changes following irradiation.

Radiotherapy is used for curative and palliative treatment. However, its negative effect on normal tissue is a limiting factor for the deliverable dose. Microcirculatory breakdown and prolonged inflammation in particular are major features of late side effects. The purpose of this study was to develop a reliable animal model that will allow a long-term in vivo analysis of microcirculation and inflammation following irradiation. A single dose of 90 Gy was delivered to the ears of hairless mice (n = 15). Intravital fluorescent microscopy was used to assess microcirculatory parameters and leukocyte behaviour. Values for the identical (control) areas were obtained before as well as during the following days, weeks and months following irradiation. The arteriolar and venular diameter increased up to Day 14, decreased during the following months, and increased again after one year. The red blood cell velocity increased up to 145% on Day 3, decreased on Day 7 to 115%, and stayed above baseline value the whole year. The integrity loss of the endothelium increased up to Day 7 and continued up to Day 75 after radiation. After one year, the oedema was at the baseline level. Leukocytes showed their maximal activity at one year after trauma. An increase was measured up to Day 25; the lowest values were measured at Day 40 post-irradiation, followed by a repeated increase. The present model allows a certain visualization of microcirculatory disturbances and inflammation over a period of months. This permits the possibility of long-term investigations of the underlying pathophysiology following irradiation, including possible drug interactions.

Short-term effects of extracorporeal shock waves on microcirculation.

BACKGROUND: Extracorporeal shock wave application (ESWA) has the potential to qualify as an adjuvant therapy option for soft tissue disorders such as chronic wounds. As of today, little is known about its exact mechanism of action. For a better understanding of the pathophysiology, we investigated the effect of ESWA on microcirculation and leukocyte-endothelial interaction. MATERIALS AND METHODS: Intravital fluorescent microscopy was used to quantify microcirculatory parameters in the ears of hairless mice (n = 30). Values were obtained just before and 10 min after the ESWA (500 shots, 1 Hz, duration 500 s). Mice were randomly divided into three groups undergoing different shock wave intensities (energy flux density: control: 0.00 mJ/mm(2); low level: 0.015 mJ/mm(2); and higher level (hl): 0.04 mJ/mm(2); n = 10 mice per group). Histologic evaluations were taken after completion of the experiments. RESULTS: A significant increase in the venular diameter was observed in both the groups that underwent ESWA compared with the control group (hl: 118%, low level: 117%, and control: 96%; P < 0.004). Edema formation increased significantly in group I (P = 0.002). ESWA provoked an arteriolar constriction (hl: 93% versus control: 104%; P = 0.019) 10 min after treatment. The highest value of venular blood flow was found in group hl. Moreover, shock waves increased significantly the number of sticking leukocytes immediately after application (hl: 274%, P = 0.003). CONCLUSIONS: ESWA has a significant and immediate impact on microcirculation with endothelial integrity loss and increase of adherent leukocytes as part of a proinflammatory process. Although a dilation of venules was caused, arterioles primarily show a constriction. The study shows alterations in microcirculation that could help understand the mechanism of action in the future.

Peptide XIB13 reduces capillary leak in a rodent burn model.

OBJECTIVE: Edema due to capillary leak is a generalized and life threatening event in sepsis and major burns for which there is no causal treatment. Local burn wounds are an ideal model to investigate the impact of a new therapeutic agent on edema formation. We aimed to identify peptide sequences of cingulin that can attenuate stress-induced endothelial cytoskeleton disarrangement in vitro and which reduce burn-induced edema in vivo. METHODS: Cingulin-derived peptides were screened in high content cell culture assays monitoring actin displacement and endothelial cell/cell contacts. The ears of male hairless mice (n=44) were inflicted with full thickness burns using a hot air jet. Mice with and without burn injuries were treated with Xib13 or solvent by continuous intraperitoneal application for 3 days. Edema, microcirculation, leukocyte-endothelial interactions and angiogenesis - measured as non-perfused area - were investigated over a 12-day period using intravital fluorescence microscopy. RESULTS: Xib13 reduced endothelial stress formation and stabilized endothelial tight junctions in cell-cultures. In the burn model, Xib13 improved angiogenesis compared to controls (non-perfused area on day 12: 5.7±1.5% vs. 12.0±2.1%; p<0.05). Edema was significantly reduced at all observation points in Xib13-treated animals as compared to controls (day 12: 67.6±2.6% vs. 83.2±6.4%). CONCLUSION: Xib13 improved angiogenesis, reduced edema formation and showed no side effects on other physiological parameters. Since edema formation is a serious parameter for burn conversion and is associated with survival it could provide a new treatment option for patients with burn injuries.