Bewährte und aktuelle Verfahren in der Wundheilung

In Vitro Evaluation and Mechanism Analysis of the Fiber Shedding Property of Textile Pile Debridement Materials

Fiber shedding is a critical problem in biomedical textile debridement materials, which leads to infection and impairs wound healing. In this work, single fiber pull-out test was proposed as an in vitro evaluation for the fiber shedding property of a textile pile debridement material. Samples with different structural design (pile densities, numbers of ground yarns and coating times) were prepared and estimated under this testing method. Results show that single fiber pull-out test offers an appropriate in vitro evaluation for the fiber shedding property of textile pile debridement materials. Pull-out force for samples without back-coating exhibited a slight escalating trend with the supplement in pile density and number of ground yarn plies, while back-coating process significantly raised the single fiber pull-out force. For fiber shedding mechanism analysis, typical pull-out behavior and failure modes of the single fiber pull-out test were analyzed in detail. Three failure modes were found in this study, i.e., fiber slippage, coating point rupture and fiber breakage. In summary, to obtain samples with desirable fiber shedding property, fabric structural design, preparation process and raw materials selection should be taken into full consideration.

Response of endothelial cells and pericytes to hypoxia and erythropoietin in a co-culture assay dedicated to soft tissue repair

The increasing mean life expectancy of the citizens of the western world countries leads to an increase of the age-related diseases, among them soft tissue defects exhibiting inadequate healing. In order to develop new therapeutic strategies to support disturbed soft tissue repair, there is a strong need of sophisticated in vitro assays. A new assay combining scratch wounding with co-cultures of primary human microvascular endothelial cells (HDMEC) and pericytes (HPC) focuses on basic characteristics of cell interaction against the background of soft tissue repair. The cell parameters proliferation, migration and differentiation, and the release of monocyte chemoattractant protein-1 (MCP-1) were analysed in response to hypoxia (pO2 < 5 mmHg) and to erythropoietin (EPO; 50 IU/ml), a glycoprotein hormone having shown promising effects in soft tissue repair. As basic characteristics of the assay, direct cell contact in co-culture led to a weakened proliferation of both cell types, an increase of the percentage of myofibroblast-like pericytes and to a higher release of MCP-1. Hypoxia caused a proliferation decrease of HPC in co-culture, which was slightly attenuated by EPO. Hypoxia also reduced the MCP-1 release of co-cultured cells, when EPO had been added. In addition, EPO had a rather positive effect on HPC migration under hypoxia. These in vitro results allow new insights into the interaction of pericytes with endothelial cells in the context of soft tissue repair.

Evidence-based topical management of chronic wounds according to the T.I.M.E. principle

The number of patients suffering from chronic wound healing disorders in Germany alone is estimated to be 2.5-4 million. Therapy related expenses reach 5-8 billion Euros annually. This number is partially caused by costly dressing changes due to non-standardized approaches and the application of non-evidence-based topical wound therapies. The purpose of this paper is to elucidate a straightforward principle for the management of chronic wounds, and to review the available evidence for the particular therapy options. The T.I.M.E.-principle (Tissue management, Inflammation and infection control, Moisture balance, Epithelial [edge] advancement) was chosen as a systematic strategy for wound bed preparation. Literature was retrieved from the PubMed and Cochrane Library databases and subjected to selective analysis. Topical wound management should be carried out according to a standardized principle and should further be synchronized to the phases of wound healing. Despite the broad implementation of these products in clinical practice, often no benefit exists in the rate of healing, when evaluated in meta-analyses or systematic reviews. This insufficient evidence is additionally limited by varying study designs. In case of non-superiority, the results suggest to prefer relatively inexpensive wound dressings over expensive alternatives. Arbitrary endpoints to prove the effectiveness of wound dressings, contribute to the random use of such therapies. Defining rational endpoints for future studies as well as the deployment of structured therapy strategies will be essential for the economical and evidence-based management of chronic wounds.

Bromelain down-regulates myofibroblast differentiation in an in vitro wound healing assay

Bromelain, a pineapple-derived enzyme mixture, is a widely used drug to improve tissue regeneration. Clinical and experimental data indicate a better outcome of soft tissue healing under the influence of bromelain. Proteolytic, anti-bacterial, anti-inflammatory, and anti-oedematogenic effects account for this improvement on the systemic level. It remains unknown, whether involved tissue cells are directly influenced by bromelain. In order to gain more insight into those mechanisms by which bromelain modulates tissue regeneration at the cellular level, we applied a well-established in vitro wound healing assay. Two main players of soft tissue healing--fibroblasts and microvascular endothelial cells--were used as mono- and co-cultures. Cell migration, proliferation, apoptosis, and the differentiation of fibroblasts to myofibroblasts as well as interleukin-6 were quantified in response to bromelain (36 × 10(-3) IU/ml) under normoxia and hypoxia. Bromelain attenuated endothelial cell and fibroblast proliferation in a moderate way. This proliferation decrease was not caused by apoptosis, rather, by driving cells into the resting state G0 of the cell cycle. Endothelial cell migration was not influenced by bromelain, whereas fibroblast migration was clearly slowed down, especially under hypoxia. Bromelain led to a significant decrease of myofibroblasts under both normoxic (from 19 to 12 %) and hypoxic conditions (from 22 to 15 %), coincident with higher levels of interleukin-6. Myofibroblast differentiation, a clear sign of fibrotic development, can be attenuated by the application of bromelain in vitro. Usage of bromelain as a therapeutic drug for chronic human wounds thus remains a very promising concept for the future.

Wundauflagen in der Therapie chronischer Wunden

Einleitung: Die nicht heilende Wunde stellt einen zunehmenden Kostenfaktor im Gesundheitssystem dar. Ziel der fachgerechten Wundtherapie ist es, die gestörte Wundhei-lung zu durchbrechen, um das Durchlaufen der physiologischen Abheilung zu ermögli-chen.

Methoden: Es erfolgte eine selektive Literaturrecherche in den Datenbanken AWMF, PubMed und Cochrane Library mit den Schlüsselwörtern „chronic wound” oder „ulcer” in Kombination mit den Begriffen alginates, hydrofibre, hydrogel, collagen, foam.

Ergebnisse: Die heute verfügbaren Wundtherapeutika erlauben es nicht, bei chronischen Wunden anstelle einer narbigen Reparatur eine physiologische Regeneration der Haut zu erreichen. Vor jeder Wundtherapie müssen mögliche Ursachen für die gestörte Wundhei-lung identifiziert werden und sofern möglich kausal therapiert werden. Zur topischen Therapie chronischer Wunden steht eine große Auswahl verschiedener Wundauflagen zur Verfügung. Die dezidierte Kenntnis dieser Wundtherapeutika ermöglicht deren differenzierten Einsatz, und ist damit die Voraussetzung für eine heilungsphasenadaptierte Anwendung.

Schlussfolgerung: Die derzeitige Studienlage erlaubt kaum Rückschlüsse auf die Überlegenheit einzelner Wundauflagen bezüglich des Endpunktes Wundverschluss. Obwohl die mangelhafte Evidenz die Entscheidung bei den Behandelnden für oder gegen die einzelnen Produkte erschwert, zeigt es auch, dass teure Wundauflagen preiswerteren Alternativen nicht eindeutig überlegen sind.

Contact dermatitis due to use of Octenisept in wound care

BACKGROUND

Octenisept, containing 0.1 % octenidine/2 % phenoxyethanol, is a widely used antiseptic in modern wound management. It is considered to have a very low allergenic potential. Thus far, neither allergic nor irritant contact dermatitis to the product has been described.

PATIENTS AND METHODS

Chronic wounds in 251 patients were treated with Octenisept; 11 developed signs of contact dermatitis. The symptoms improved after discontinuation of the antiseptic. Eight of these patients were patch tested to the antiseptic and its components.

RESULTS

The eight patients all showed a positive reaction to the product. In at least three cases a reaction to the components cocamidopropyl betaine and phenoxyethanol was found, but not to octenidine dihydrochloride.

CONCLUSIONS

In this cohort, more than three percent of the treated patients developed a contact dermatitis to the antiseptic. However, the differentiation between allergic and irritant contact dermatitis towards the ingredients of the antiseptic remains problematic.

[Pathogenesis of chronic wounds]

Chronic, nonhealing wounds and their therapy are not only a medical problem but a severe economic one as well. Such wounds have a great effect on quality of life. Basic research has enhanced our understanding of the stimulation and inhibition of wound healing and provides the basis for introducing new and innovative treatment methods. This paper reviews the most relevant in- and extrinsic factors that disturb physiologic wound healing to result in chronic nonhealing wounds. In addition, molecular intervention modalities targeting various aspects of wound repair are demonstrated.

Hyperplastische Narben und Keloide

Aberrant wound healing results in unsightly scarring, hypertrophic scarring, and keloid formation, causing functional and cosmetic deformities, discomfort, psychological stress, and patient dissatisfaction. Scar prevention and management continue to be important issues for the facial plastic surgeon. This article presents an overview on the pathogenesis of a scar and of the different types of scars. Differences between keloids, hypertrophic scars and normal scars include distinct scar appearance, histologic morphology and cellular function in response to growth factors. Recent advances in our understanding of the wound healing process reveal possible causes for hypertrophic scars and keloids. This information might assist in the development of efficacious prevention and treatment for hypertrophic scar and keloid formation. This article also describes the strategies available for scar prevention. Recommendations focus on the management of hypertrophic scars and keloids.

Does the use of low-level laser influence wound healing in chronic venous leg ulcers?

OBJECTIVE

Venous leg ulcer treatment often requires months or years of regular wound care by trained staff. It has been suggested that low-level laser irradiation has a biostimulative and wound healing effect, but this has not been clinically verified by controlled studies. This study aimed to compare the effectiveness of low-level laser irradiation with that of a placebo 'light source'.

METHOD

Forty-four patients were assigned to two treatment groups (laser and placebo) or a third group (standardised treatment only) to quantify the effect of the laser therapy. Patients in all three groups received standardised wound care (disinfection, a hydrofibre dressing and compression bandaging). Ulcer size was measured at baseline (day 1), at the end of therapy (day 28) and then two months later (day 90). The relative difference in wound size was evaluated.

RESULTS

The difference in the reduction in wound size was not statistically significant in all three groups. A positive effect of using the non-laser device (placebo effect) was demonstrated in some patients.

CONCLUSION

These study results suggest that low-level laser does not stimulate wound healing in venous leg ulcers. Further controlled studies are needed to clarify the efficacy of low-level laser treatment as a wound-healing stimulant.