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Tissue Engineering: how injuries can be treated more effectively

Burns are one of the major accidents the doctors at the BG Casualty Hospital in Tübingen have to deal with. They are currently using regenerative therapies to support the self-healing power of the body.

"When we see how much severely burnt children are affected by scar formation, we feel the need to do something about it" that is how Prof. Dr. Hans-Oliver Rennekampff describes his and his team's motivation for working on the improvement of therapies for the treatment of burns victims. In Germany, around one thousand people are affected by severe 3rd degree burns every year. In such cases, the skin is completely burnt leaving behind areas depleted of cells that would otherwise be able to induce the regeneration of the damaged skin. Although there is a possibility of transplanting skin from other parts of the body to the affected area, in many cases there is not enough safe skin available.

That is why the researchers are working hard on developing skin replacements that can be grown from the patients' own cells in the laboratory. The emphasis lies on "replacement" because the scientists are well aware that they are far from being able to develop a fully functional skin. "We won't be able to create a natural skin type in the foreseeable future, but we hope that we are coming a good step closer to being able to produce near-normal skin," said Rennekampff.

As things stand at the moment, the laboratory-made skin has several disadvantages: It requires constant care and lotion has to be continuously applied because such skin replacements have no mechanisms for protecting the organ from sunlight. It also has no sweat glands and is therefore unable to operate a cooling system. In cooperation with Prof. Dr. Thomas Skutella's group at the Anatomical Institute at the University of Tübingen, Rennekampff and his colleagues are currently evaluating a tissue type in the mouse model, which is cultivated in co-culture with adult bone-marrow derived stem cells.

With stem cells closer to the original

The researchers hope that the use of stem cells will provide them with a skin consisting of different cell types, which, in common with real skin, will also be able to carry out different functions. "The experiments are promising and we are confident that we will get a great deal closer to the original. That's why we intend to intensify this type of research and hope to acquire extra funds," said Rennekampff. Nevertheless, he does not see the currently used acellular skin replacement as out-dated. Quite the contrary – Rennekampff is working on approaches that combine both cultured tissue and acellular replacement materials. "This would considerably simplify the application of the grafts," said the skin specialist.

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Cultivated keratinocytes and fibroblasts are mixed with adult bone-marrow derived stem cells. The cell suspension is applied to the wound here it is shown in an animal model. (Photos: Prof. Rennekampff)

Skin replacement can also considerably increase the chances of curing chronic wounds. In contrast to burns, chronic wounds still have a sufficient number of cells that are able to induce regeneration of the affected area. However, they are unable to grow over the wound base. "There is no adequate wound bed that would help the skin to grow back together," said Rennekampff, who is looking for different kinds of wound dressings that are able to actively stimulate the skin to grow back together – potentially also through the addition of growth factors.

Reliable test site for industry products

In order to reach their goal quicker, Rennekampff supports interdisciplinary cooperation and is very interested in establishing intensive contacts with industrial and research partners - "When a company has developed a new wound dressing that has been certified and approved, we will then test the material for inertness and look into whether it is more effective than previous solutions," said Rennekampff.

The suspension of keratinocytes and fibroblasts leads to the closure of the skin. The epidermis tends to regenerate well.

The suspension of keratinocytes and fibroblasts leads to the closure of the skin. The epidermis tends to regenerate well.

Suspension of keratinocytes, fibroblasts and bone-marrow cells. (Photos: Prof. Rennekampff)

Suspension of keratinocytes, fibroblasts and bone-marrow cells. (Photos: Prof. Rennekampff)


Renekampff's team is also working in close cooperation with the Fraunhofer Institute of Interfacial Engineering and Biotechnology (IGB) in Stuttgart: "We provide advice and support for the development of skin systems for industrial research. The skin systems will be used to replace animal experiments."

Biomaterial encounter huge obstacles in the authorisation process

Obtaining authorisation for the use of acellular materials only creates minor problems. "This is possible in spite of the fact that time-consuming cell compatibility tests have to be carried out." The situation is completely different where biological products are concerned. "Products in which cells, and specifically foreign cells, are used, run into virtually insurmountable obstacles in Germany." Restrictive legislation, which is even more restrictive in Germany than required by EU regulations, runs into fundamental problems in the application of biological materials. "Naturally, biological products vary and cannot be standardised," said Rennekampff. As industry is careful with its investment decisions in the field of biomaterials, Rennekampff and his colleagues find it difficult to find cooperation partners for the further development of skin replacement materials. Nevertheless, he is always open to new approaches and hopeful that the efforts in this area will be intensified.

leh - 17.10.06
© BIOPRO Baden-Württemberg GmbH, first published at www.bio-pro.de<, the Biotech/Life Sciences Portal of the State of Baden-Württemberg. All rights reserved.

Further information:

BG Unfallklinik - Casualty Hospital Tübingen
Hospital for Hand, Plastic, Reconstructive and Burn Surgery
Prof. Dr. Hans-Oliver Rennekampff
(Head of the Department of Burn Surgery and Skin Regeneration)
Schnarrenbergstr. 95
72076 Tübingen

Phone: +49 (0)7071 606-1172
Fax: +49 (7)071 606-1037
rennekampff [at] bgu-tuebingen [dot] de www.bgu-tuebingen.de<