K. Riedel

Perspectives of Gene Therapy in Stem Cell Tissue Engineering

Tissue engineering is an interdisciplinary field that applies the principles of engineering and life sciences toward the development of biological substitutes that restore, maintain or improve tissue function. It is hoped that forming tissue de novo will overcome many problems in plastic surgery associated with such areas as wound healing and the immunogenicity of transplanted tissue that lead to dysfunctional repair. Gene therapy is the science of the transfer of genetic material into individuals for therapeutic purposes by altering cellular function or structure at the molecular level. Recently, tissue engineering has been used in conjunction with gene therapy as a hybrid approach. This combination of stem-cell-based tissue engineering with gene therapy has the potential to provide regenerative tissue cells within an environment of optimal regulatory protein expression and would have many benefits in various areas such as the transplantation of skin, cartilage or bone. The aim of this review is to outline tissue engineering and possible applications of gene therapy in the field of biomedical engineering as well as basic principles of gene therapy, vectors and gene delivery.

High-dose vitamin C treatment reduces capillary leakage after burn plasma transfer in rats.

Oxidative stress after burn injuries leads to systemic capillary leakage and leukocyte activation. This study evaluates whether antioxidative treatment with high-dose vitamin C leads to burn edema reduction and prevention of leukocyte activation after burn plasma transfer. Donor rats underwent a burn (n = 7; 100°C water, 12 seconds, 30% body surface area) or sham burn (37°C water; n = 2) procedure and were killed after 4 hours for plasma harvest. This plasma was administered to study rats (continuous infusion). Rats were randomized to four groups (n = 8 each; burn plasma alone [BP]; burn plasma/vitamin C-bolus 66 mg/kg and maintenance dose 33 mg/kg/hr [VC66]; burn plasma/vitamin C-bolus 33 mg/kg and maintenance dose 17.5 mg/kg/hr [VC33]; and sham burn plasma [SB]). Intravital fluorescence microscopy in the mesentery was performed at 0, 60, and 120 minutes for microhemodynamic parameters, leukocyte adherence, and fluorescein isothiocyanate-albumin extravasation. No differences were observed in microhemodynamics at any time. Burn plasma induced capillary leakage, which was significantly higher compared with sham burn controls (P < .001). VC66 treatment reduced microvascular barrier dysfunction to sham burn levels, whereas VC33 had no significant effect. Leukocyte sticking increased after burn plasma infusion, which was not found for sham burn. Vitamin C treatment did not influence leukocyte activation (P > .05). Burn plasma transfer leads to systemic capillary leakage. High-dose vitamin C treatment (bolus 66 mg/kg and maintenance dose 33 mg/kg/hr) reduces endothelial damage to sham burn levels, whereas half the dose is inefficient. Leukocyte activation is not influenced by antioxidative treatment. Therefore, capillary leakage seems to be independent from leukocyte-endothelial interactions after burn plasma transfer. High-dose vitamin C should be considered for parenteral treatment in every burn patient.

Suprathel―Acetic Acid Matrix Versus Acticoat and Aquacel as an Antiseptic Dressing: An In Vitro Study

Background:The treatment of burn wounds is still a challenge regarding the management of antiseptic wound conditioning. Especially, in the United States, silver-containing dressings, such as Acticoat and Aquacel are frequently used. Because silver-containing dressings have well-known drawbacks such as an antimicrobial lack against Pseudomonas aeruginosa, we sought to develop an alternative dressing method. In previous studies, we could demonstrate the excellent antiseptic properties of acetic acid against common burn unit germs, and in another study, the feasibility and suitability of a Suprathel–acetic acid matrix as an antiseptic dressing. Materials and Methods:This study was designed to test the in vitro antimicrobial effect of a Suprathel–acetic acid matrix versus Acticoat and Aquacel. To cover the typical bacterial spectrum of a burn unit, the following Gram-negative and Gram-positive bacteria strains were tested: Escherichia coli, extended-spectrum beta-lactamase–positive Klebsiella pneumoniae, P. aeruginosa, Acinetobacter baumannii, Enterococcus faecalis, and methicillin-resistant Staphylococcus aureus. Results:The tests showed an excellent bactericidal effect of the Suprathel–acetic acid matrix particularly with problematic Gram-negative bacteria such as Proteus vulgaris, P. aeruginosa, and Acinetobacter baumannii. The efficiency was superior to that of Acicoat and Aquacel. Conclusions:Our results support the notion, that the Suprathel–acetic acid matrix has an excellent bactericidal effect and therefore seems to be suitable as a local antiseptic agent in the treatment of burn wounds.

Tissue engineering in head and neck reconstructive surgery: what type of tissue do we need?

Craniofacial tissue loss due to congenital defects, disease or injury is a major clinical problem. The head and neck region is composed of several tissues. The most prevalent method of reconstruction is autologous grafting. Often, there is insufficient host tissue for adequate repair of the defect side, and extensive donor site morbidity may result from the secondary surgical procedure. The field of tissue engineering has the potential to create functional replacements for damaged or pathologic tissues.

Pathophysiologie der chronischen Wunde

ZusammenfassungChronische Wunden und ihre Therapie sind nicht nur ein wichtiges medizinisches, sondern vor allem auch ein großes gesellschaftliches Problem, denn sie führen zu einer sozialen Isolierung der Patienten, zu lang andauernder Arbeitsunfähigkeit und sie beeinträchtigen die Lebensqualität der Betroffenen nachhaltig. Um suffiziente Therapiemöglichkeiten zu entwickeln, ist das Verständnis der Wundheilungsvorgänge sowie der Faktoren, die die physiologische Wundheilung stören, eine wichtige Grundvoraussetzung. Diese Arbeit soll einen Überblick über die wichtigsten intrinsischen und extrinsischen Faktoren geben, die eine physiologische Wundheilung stören können und so zur Entwicklung einer chronischen Wunde führen. Ansatzpunkte, die sich hieraus für eine molekulare Beeinflussung der Wundheilung ergeben, werden dargestellt.AbstractChronic, 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.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.

Topical application of cerium nitrate prevents burn edema after burn plasma transfer.

Thermal injuries of more than 20% body surface area (BSA) result in systemic capillary leakage with subsequent edema. This can similarly be induced by burn plasma transfer (BPT) from burned individuals to healthy rats. We evaluated if cerium nitrate (CN) bathing can prevent edema after BPT. Therefore, donor rats (DR) underwent thermal injury (100 degrees C water, 30%BSA, 12 s) for positive controls and were additionally bathed in CN (0.05M, at 10 and 120 min) for study groups. For negative controls DR underwent shamburn (37 degrees C water, 30%BSA, 12 s). DR-plasma (harvested 4 h post trauma) was transferred to healthy individuals. Intravital microscopy was performed in mesenteric venules (0/60/120 min). Edema was assessed by FITC-albumin extravasation. Additionally, leukocyte sticking (cells/mm(2)) and micro hemodynamic parameters were assessed. Significant systemic capillary leakage was observed after BPT at 120 min. Edema formation was significantly lower in negative controls. Topical CN application after 10 and 120 min reduced FITC-efflux to baseline levels. Adherent leukocytes increased slightly in all groups. Leukocyte-sticking tended to be reduced after CN bathing. In conclusion, BPT induces burn edema in healthy individuals. CN bathing after 10 and 120 min reduces mediator levels in burned individuals. Therefore, BPT after CN application does not induce burn shock anymore. Burn edema is partially independent from leukocyte activation because CN significantly influences macromolecular leakage whereas leukocyte activation is not significantly altered.

Regenerative Medicine in head and neck reconstructive surgery

ZusammenfassungDie Verwendung autologer Transplantate gilt als Goldstandard in der Therapie kongenitaler oder erworbener Defekte. Die Gewinnung autologer Transplantate ist jedoch oft limitiert. Die regenerative Medizin zielt auf die intrinsischen, autologen regenerativen Mechanismen des Individuums und vereint die Kentnisse des Tissue-Engineerings, der Zell- bzw. Systembiologie, der Gentherapie und der Stammzellbiologie. Die meisten Ansätze des Tissue-Engineerings basieren auf der Expansion kleiner autologer Zellverbände des Patienten. Tissue-Engineering mit Hilfe von isolierten und amplifizierten Stammzellen stellt eine weitere vielversprechende Möglichkeit zur Herstellung autologer Transplantate dar und so die limitierte Verfügbarkeit zu überwinden. Die Kombination stammzellbasierten Tissue-Engineerings mit der Gentherapie erlaubt es, regeneratives Gewebe im optimalen Umfeld von Regulatorproteinen zu schaffen. Hieraus ergeben sich große Chancen für die Transplantation von Haut, Knochen oder Knorpel. In diesem Beitrag sollen der aktuelle Stand, der mögliche Nutzen, aber auch die Grenzen der regenerativen Medizin für die rekonstruktive Kopf-Hals-Chirurgie herausgestellt werden.AbstractAutologous transplantation is regarded as the gold standard in the treatment of congenital or acquired deformities. However, the availability of autologous tissue for transplantation is often limited. Regenerative medicine aims to activate individuals’ own intrinsic regenerative mechanisms and embraces tissue engineering, cell/system biology, gene therapy and stem-cell biology. Most approaches in tissue engineering are based on the expansion of small autologous cell aggregates. Tissue engineering supplemented by isolated and amplified stem cells is another very promising option for producing autologous transplants and getting over the limited availability. The association of stem cell-based tissue engineering and gene therapy allows the creation of regenerative tissue in the optimal ambience of regulatory proteins. This leads to great opportunities in the transplantation of skin, bones or cartilage. This paper presents the current status and the possible benefits, but also the limitations, of regenerative medicine in reconstructive surgery of the head and neck.

Antiseptic therapy with a polylacticacid-acetic acid matrix in burns

Bacterial colonization and infection are still the major causes of delayed healing and graft rejection following burns and they are furthermore the basis for second and third hit sepsis. Topical treatment is necessary to reduce the incidence of burn wound infection. Silver sulphadiazine (SD‐Ag) is a frequently used microbicidal agent. However, this treatment causes adverse reactions and side‐effects. Additionally, in recent years multiresistant bacteria, which have not been treated sufficiently, are on the rise. On the basis of experimental data and clinical application of a polylacticacid–acetic acid matrix, we performed this study to establish the effectiveness of the antiseptic therapy with the topical application of a polylacticacid–acetic acid matrix to provide an alternative method for burn treatment, using SD‐Ag as a reference. Twenty patients with IIb° or III° burns from the Plastic Surgery and Burns Unit were treated within a matched pair comparative setting. One burned area was treated with SD‐Ag, the other corresponding area with the polylacticacid–acetic acid matrix. All patients underwent a necrectomy 4–5 days after the trauma. The excised burned skin was sent to our microbiological laboratory to determine the different bacteria per gram in this tissue. Despite the number of 20 patients, statistical significance was not achieved, there were tendencies to a better antiseptic effectiveness of the polylacticacid–acetic acid matrix. These results suggest that the polylacticacid–acetic acid matrix should be studied in greater depth and could be used as a valid alternative for the topical treatment of burns, as it is equivalent or even more effective than SD‐Ag.

Optimizing Suprathel®-therapy by the use of Octenidine-Gel®

OBJECTIVE A prospective, randomized, non-blinded, clinical study was conducted to evaluate the feasibility and practicability as well as pain reduction and ease of handling of Flammazine® versus Octenidine-Gel® s a primary local antiseptic before synthetic skin substitute application in partial-thickness burns. METHODS Thirty patients with a median age of 42 years suffering from second-degree burns were included in the study. Burns were randomly selected, one area was treated with Flammazine®/gauze, another area in the same patient was treated with Octenidine-Gel®/gauze as initial antiseptic treatment. Within 24 h the first gauze change was performed followed by wound inspection, disinfection and synthetic skin substitute application. The study focused on patient pain score, analysis of wound bed and ease of handling of the two local antiseptic agents. RESULTS There was a significant difference between Flammazine® versus Octenidine-Gel® regarding patient pain score and ease of handling. Octenidine-Gel® was less painful (p < 0.05) and easier to handle (p < 0.05). There was no significant difference for wound bed evaluation between the two antiseptic agents. A tendency for better wound bed preparation was seen with the use of Octenidine-Gel®. CONCLUSION Based on the findings of this study Octenidine-Gel® is recommended as a local antiseptic agent, because when compared to Flammazine®, Octenidine-Gel® proved to be better in terms of ease of care, simplicity application, with gentler and faster detachment of the gel from wound surfaces and consequently far less pain during dressing changes.

Pathogenesis of chronic wounds

ZusammenfassungChronische Wunden und ihre Therapie sind nicht nur ein wichtiges medizinisches, sondern vor allem auch ein großes gesellschaftliches Problem, denn sie führen zu einer sozialen Isolierung der Patienten, zu lang andauernder Arbeitsunfähigkeit und sie beeinträchtigen die Lebensqualität der Betroffenen nachhaltig. Um suffiziente Therapiemöglichkeiten zu entwickeln, ist das Verständnis der Wundheilungsvorgänge sowie der Faktoren, die die physiologische Wundheilung stören, eine wichtige Grundvoraussetzung. Diese Arbeit soll einen Überblick über die wichtigsten intrinsischen und extrinsischen Faktoren geben, die eine physiologische Wundheilung stören können und so zur Entwicklung einer chronischen Wunde führen. Ansatzpunkte, die sich hieraus für eine molekulare Beeinflussung der Wundheilung ergeben, werden dargestellt.AbstractChronic, 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.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.