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Human fibroproliferative disorders like hypertrophic scarring of the skin are characterized by increased contractility and excess extracellular matrix synthesis. A beneficial role of transforming growth factor (TGF)-␤ in wound healing was proposed; however, chronic stimulation by this cytokine leads to fibrosis. In the present report, the intracellular TGF-␤ signaling in fibroblasts derived from hypertrophic scars and normal skin was examined. In an attempt to intervene in profibrogenic TGF-␤ functions, ectopic expression of Smad7 or dominant negative Smads3/4 completely inhibited contractility of scar-derived and normal fibroblasts after suspension in collagen gels. Both cell types displayed constitutive Smad2/3 phosphorylation and (CAGA) 9 -MLP-Luc activity with expression and phosphorylation of Smad3 being predominant in hypertrophic scar-derived fibroblasts. Down-regulation of intrinsic signaling with various TGF-␤ antagonists, e.g. soluble TGF-␤ receptor, latency-associated peptide, and anti-TGF-␤ 1 antibodies, confirms autocrine TGF-␤ stimulation of both cell populations. Further, Smad7 expression inhibited ␣1 (I) collagen and ␣-smooth muscle actin expression. In summary, our data indicate that autocrine TGF-␤/Smad signaling is involved in contractility and matrix gene expression of fibroblasts from normal and hypertrophic scars. Smad7 inhibits these processes and may exert beneficial effects on excessive scar formation.

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Application of C1Inh appears to be an effective means to prevent capillary leakage and inflammatory tissue destruction after thermal trauma.

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Angiogenesis is essential in wound healing and a common feature in chronic inflammation which is crucially involved in the biological response to biomaterials. A useful system to evaluate the angiogenic activity and the inflammatory potency of various agents is the chorioallantoic membrane (CAM) of the chick embryo. Here we examined its response to different biomaterials. Smooth materials such as PVC or the polyurethane Tecoflex either unmodified or modified by an OH- or N(CH(3))(3)(+)-end group (HEMA or MAPTAC) inhibited angiogenesis and did not induce the formation of granulation tissue. The anti-angiogenic effects of PVC, Tecoflex and its HEMA modification, however, were only seen at an early stage of development. In contrast, the MAPTAC modified Tecoflex inhibited angiogenesis over the whole time. Rough materials, e.g. filter paper or a collagen/elastin membrane, stimulated angiogenesis and induced the formation of inflammatory tissue. Histological analysis revealed that the filter material was homogeneously populated with cells consisiting mainly of macrophages, fibroblasts and endothelial cells. The collagen/elastin membrane was only partially infiltrated with cells. Among those also clusters of granulocytes were present pointing to an acute inflammatory process. These data show that the angiogenic activity and inflammatory response of biomaterials strongly depend on the chemical composition and the physical structure of the material. The CAM assay appears to be a useful tool for studying biocompatibility.

Next to in vitro-cultured autogeneic keratinocytes for the restoration of epidermis, a suitable dermal matrix is a mandatory component of an artificial skin substitute for the permanent covering of full thickness skin defects. In our model a xenogeneic membrane, consisting of processed native collagen and elastin of porcine origin is meant to serve as a template for the formation of a neo-dermis. In order to improve the resistance of this matrix against enzymatical degradation, we cross-linked it by using the carbodiimide 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) together with N-hydroxysuccinimide. Chemical cross-linking by these agents at two different degrees (shrinkage temperatures 63 degrees C and 81 degrees C) had no relevant effect on mechanical features or water-uptake capacity. The time needed for enzymatic digestion was increased by cross-linking. Concerning growth and spreading of fibroblasts and keratinocytes on and within the structure of this membrane, we did not observe a difference between cross-linked and non-cross-linked material (shrinkage temperature 48 degrees C). We therefore expect that cross-linking by EDC is an effective means to control the degradation of the collagen/elastin membranes in vivo without a significant influence on their biocompatibility.

Anesthesia of the pig poses great problems for experimental animal-based research and particularly in shock research. In this study, five mechanically ventilated domestic pigs were given long-term anesthesia with a combination of ketamine plus pentobarbital. Circulatory parameters were recorded every 2 h via an arterial catheter placed in the right common carotid artery, a Swan-Gans thermodilution catheter (7F), that was placed in the pulmonary artery of the right middle-lobe in a wedge position through the external jugular vein, and another catheter in the internal jugular vein for measuring central venous pressure. Moreover, body weight, blood gases, pH, blood cells, electrolytes and serum enzymes were measured. Further serum traits as total protein and glucose and pathological alterations in different organs were recorded. The animals were observed for a period of 96 h and then killed painlessly. It was shown that pigs can survive 96-h anesthesia with the combination of ketamine and pentobarbital. Optimum, carefully controlled anesthesia did not impair the integrity of the regulatory mechanisms of circulation.