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Wolfgang Pfützner

Publications and source records attributed to Wolfgang Pfützner.

7 recordsLinked to original sources
PubMed2006

A large preclinical animal model to assess ex vivo skin gene therapy applications.

Because of its easy accessibility, the skin is a very attractive target for gene therapy purposes. To study potential clinical applications in a preclinical setting, appropriate animal models are needed. Pig skin is very similar to human skin, and a variety of human diseases that are potentially amenable to gene therapy applications also occur in pigs. Only a few studies have analyzed the engraftment of transduced keratinocytes (KC) in pigs, however, with limited success. We describe a porcine model in which pig KC were transduced ex vivo with a retroviral vector encoding a marker gene and subsequently grafted onto the autologous host, utilizing a relatively simple grafting technique. Enhanced transduction efficiency was achieved by an optimized transduction protocol including centrifugation of the retroviral vector at a temperature of 32 degrees C. Transduced KC were then seeded onto acellular dermis, forming a stratified epidermis. Grafting was performed by creating full thickness wounds and placing the skin graft onto the muscle fascia, covered by a protective skin flap for several days. Successful engraftment of transduced KC was demonstrated by immunohistochemistry of biopsies taken at different time points, showing transgene expression in 40-50% of grafted KC. After 4 weeks, KC expressing a foreign marker gene was lost, suggesting a transgene-specific immune response in the immunocompetent pigs and highlighting the potential problems for clinical gene therapy studies when transferring new genetic material into a patient. The model presented here may be used to examine applications of skin gene therapy, where retroviral vectors encoding endogenous pig genes will be expressed in the skin.

Animals↗
PubMed2006

[Intraoperative labeling of sentinel lymph nodes with a combination of vital dye and radionuclide tracer--results in sentinel lymph node-positive patients].

BACKGROUND: Sentinel lymph node biopsy enhances the accuracy of tumor staging in patients with malignant melanoma and can help select candidates for regional lymphadenectomy. There are two techniques for identifying the sentinel lymph node: intradermal injection of a radionuclide tracer or of a blue dye. We evaluated both methods to determine how they can be best utilized to locate a sentinel lymph node. PATIENTS AND METHODS: In a retrospective study, 323 patients with melanoma (tumor thickness > or = 0.75 mm) who underwent sentinel lymph node biopsy after both radionuclide and blue dye injection were evaluated. The labeling of lymph nodes showing micrometastasis by histopathological examination was determined. RESULTS: 63 patients showed sentinel lymph nodes with micrometastasis. All of these nodes (100 %) were labeled with radionuclide tracer, but only 90 % with blue dye. In 5 patients, only radionuclide labeling identified the histopathologically-positive lymph node. In 36 patients, several sentinel lymph nodes were identified, with the histopathologically-positive nodes usually showing a higher radioactive signal intensity than the negative ones. CONCLUSION: Since in some patients histopathologically-positive lymph nodes are only labeled by radionuclide tracer, radionuclide labeling is indispensable for locating sentinel lymph nodes. In contrast, labeling with blue dye represents a supplementary method, which can simplify the recognition of the sentinel lymph node during surgery.

Female↗
PubMed2004

Topical colchicine selection of keratinocytes transduced with the multidrug resistance gene (MDR1) can sustain and enhance transgene expression in vivo.

In gene therapy, a clinically relevant therapeutic effect requires long-term expression of the desired gene at a level sufficient to correct or at least alleviate the underlying gene defect. One approach to achieve persistent as well as high-level transgene expression in a significant percentage of target cells would be to select cells expressing both the desired transgene and a linked selectable gene--such as the human multi-drug resistance (MDR1) gene--in a bicistronic vector. Because of its accessibility, the skin is a very attractive target tissue to select genetically modified cells, allowing topical application of a selecting agent, thus minimizing potential toxic side effects. Among the potential selecting drugs, agents that block cell division, such as colchicine, are of particular interest because the use of anti-mitotic drugs takes advantage of the rapid keratinocyte (KC) turnover in the epidermis and the need for continued proliferation to substitute the KC lost due to selection. Before assessing the therapeutic benefit of such an approach, several key questions need to be answered in preclinical models: (1) Does topical colchicine application achieve the desired in vivo effect by blocking KC mitosis without eliciting unwanted toxic side effects? (2) Are MDR-transduced (MDR+) human KC still able to proliferate and differentiate when treated with colchicine? (3) Can MDR+ KC be enriched by topical selection? (4) Does topical selection result in persistent transgene expression by selecting KC stem cells expressing MDR? To answer these questions and to test the feasibility of such an approach both an in vitro skin equivalent and an in vivo human skin graft model were developed in which MDR+ KC were treated with different dosages of colchicine. Quantitative and qualitative analyses of MDR expression in human KC showed that topical colchicine treatment selects high-level transgene expression in a high percentage of KC. Moreover, determination of transgene copy numbers demonstrated that MDR+ KC progenitor cells were enriched by topical selection resulting in long-term expression of the transgene in the skin. Thus, in summary, these models demonstrate that topical selection of MDR+ KC is a safe approach to efficiently enhance long-term gene expression in the skin and holds future promise for clinical gene therapy applications.

Administration, Topical↗
PubMed2003

[Carcinogenesis: defect control systems and options for molecular therapy].

DNA mutations lead to multiple defects of different control systems necessary to regulate cell growth, cell death and cell invasion, thus resulting in the development of a malignant tumor. While the loss of single control systems can still be compensated by others, the destruction of the whole network on a molecular level will cause tumor growth. Knowledge about these control systems and their defects during carcinogenesis may it possible to design new therapeutic strategies. Among them, gene therapy offers promising treatment options.

Carcinogenesis↗
PubMed2003

[Systemic contact eczema against Balsam of Peru].

Balsam of Peru (PB; Myroxylon pereirae) is a natural product derived from resin of a tropical tree (MyroxyIon balsamum (L.) Harms var. pereirae (Royle) Baillon). Because of its antiseptic and aromatic properties PB or PB-components can be found worldwide not only in many health care and cosmetic products, but also in food items and semiluxury food. PB contains a wide variety of potent contact allergens leading to hypersensitivity reactions not only after topical application but also oral uptake. We report a 51-year-old brewer with chronic eczema of the hands who showed delayed-type patch test reactions against PB and fragrance-mix. Oral PB-challenge led to exacerbation of the eczema 5 and in a repeated test 2 days later. We here review this probably quite often overlooked disease and the therapeutic consequences which require profound knowledge about the wide distribution of PB when advising the patient about a PB-restricted diet. In addition, this unusual case report demonstrates that one has to consider marked delayed hypersensitivity reaction when investigating a systemic contact allergy.

Administration, Topical↗