Medical devices

New materials for wound healing – Skin repair kit chronic wound care

If an external injury fails to get better within a few weeks, it becomes what is known as a chronic wound. Some two percent of the population in industrialized countries is afflicted by such wounds. Apart from an abundance of wound dressings, treatment options up until now have been very limited. Bayer Innovation (BIG) is currently developing products for the treatment of these complex symptoms.

Bayer Project Managers Iwer Baecker and Dr. Burkhard Fugmann are coordinating the development of innovative plasters.

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Bayer Project Managers Iwer Baecker and Dr. Burkhard Fugmann are coordinating the development of innovative plasters.

In old age and also in conditions such as diabetes, the body is unable to get wounds to heal of their own accord. For sufferers, this often means that what was initially an apparently harmless injury turns into a serious and stressful illness. Complications such as infections usually further impair the healing process. Chronic wounds occur mainly in later life. The number of patients per year requiring treatment worldwide is already approaching 100 million, at a cost of many billions of euros. And the everageing population could further magnify the problem.

The cause of chronic wounds is an imbalance of various factors. On the one hand, cells that fuel the injury’s inflammatory response and proteases (enzymes that break down protein) go into overdrive. On the other, there is a deficiency of growth factors that are needed for generating new tissue. They are destroyed by various agents, including proteases. These enzymes could only be blocked by suitable inhibitors which are, however, likewise in too short supply. The injured tissue is often also undersupplied with oxygen.

Germ-free production: threads are produced at high pressure from liquid silica gel and placed inmolds that are laid out to dry on the changing bench by laboratory technician Kai-Michael Heuser.This results in a fibrous fleece from which the wound dressings are subsequently produced.

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Germ-free production: threads are produced at high pressure from liquid silica gel and placed in molds that are laid out to dry on the changing bench by laboratory technician Kai-Michael Heuser. This results in a fibrous fleece from which the wound dressings are subsequently produced.

BIG’s has set itself the goal with the wound healing project of developing new, innovative treatment methods. For the Bayer researchers, attention is focused on three main categories: wounds in already damaged tissue, severe burns and pressure sores. All chronic wounds are covered with wound dressings – as a barrier to invading pathogens. The dressings absorb excessive secretions, without drying out the wound. Although there are currently hundreds of different wound dressings on the market some requirements still remain unmet.

The Bayer researchers are therefore currently developing a novel dressing made of a well-known material, silica gel. This substance has long been widely used as a food supplement and is available in tablet or capsule form as silica. In order to be able to use silica gel for wound dressings, however, it had to be produced in the form of fibers that are physically stable and yet bioabsorbable, i.e. that can be broken down within the body. This breakthrough was achieved on a laboratory scale by researchers at the Fraunhofer Institute of Silicate Research (ISC) in Würzburg. Bayer Innovation adopted this novel technology platform in late 2005 and has since been engaged in targeted product development. Since May 2007, a pilot plant in Leverkusen produces the fibers according to GMP standards.

Regeneration of blood vessels accelerated

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Healing silica gel: this well-known material has long been used in tablet form as a dietary supplement. In association with other partners, Bayer Innovation is using this substance as a basis for the development of novel wound dressings that are absorbable within the body.

Various tests, for example, have shown that skin cells (fibroblasts and keratinocytes) adhere faster and better to the fiber and form new tissue. Furthermore, the three-dimensional structure of the wound closure system allows particularly rapid regeneration of blood vessels. They are particularly important to ensure that the newly formed tissue is supplied with nutrients. Wound healing takes place more swiftly than with comparable products and the newly formed tissue is more homogenous, has a more natural structure and is therefore of better quality. A further advantage is that the bioabsorbable wound dressings remain stable in the wound environment for longer. In contrast, conventional bioabsorbable materials are broken down very much faster.

The silica gel wound dressings, on the other hand, remain in the wound both for the optimum length of time and with their original structure intact, before being absorbed by the body. Furthermore, active substances that further promote wound healing can be incorporated into the fibers during the manufacturing process: Additional active substances that kill potential pathogens in open wounds. Bayer Innovation is also working on active substances that promote healing generally when applied to the wound. Firstly, supplementation of growth factors, as levels of these in chronic wounds are too low and, secondly, inhibition of the breakdown of growth factors in the chronic wound.

Three phases of healing

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Wound healing can be divided into three phases. In what is known as the coagulation and inflammation phase, blood clotting is initiated in order to stem blood flow. Wound secretion or exudate is then formed to flush pathogens and other foreign bodies out of the wound. Immune cells that have migrated to the wound likewise prevent infection by warding off germs. This inflammatory response triggers reddening and swelling of the wound area, which is often tender. At the same time, a network of fibers made of the protein fibrin is formed. One of its functions is to provide support for free skin cells. In the subsequent granulation phase, these together with the similarly fibrous protein collagen form a granular connective tissue or granulation tissue. This is transformed into mature skin only in the final regeneration phase. The silica gel wound dressings from Bayer Innovation help the wound to heal faster and promote the formation of homogenous, natural tissue.

Further informationen you will find within research - The Bayer Scientific Magazine.