P Lüscher | PubMed Health

PubMed1996

Tissue engineering scaffolds using superstructures.

Here, scaffolds as cell and tissue carriers are approached from an engineering point of view, emphasizing material superstructuring in the design of supports. Superstructure engineering provides optimal spatial and nutritional conditions for cell maintenance by the arrangement of structural elements (e.g. pores or fibres) so as to vary the order of cell to cell contact. This approach is illustrated in the design of several scaffolds: knitted fabrics as three-dimensional superstructures for optimized osteosynthesis implants, a new injectable open porous implant system, an angiopolar non-degradable ceramic cell carrier, and an injectable or microsurgically implantable entangled carrier system. The implications for tissue engineering are discussed.

Anisotropy↗

PubMed1996

Lipid metabolite involvement in the activation of the human heme oxygenase-1 gene.

Cellular effects of ultraviolet A (UVA) radiation include peroxidation of membrane lipids as well as a decrease in intracellular glutathione. We have investigated whether damage to membrane lipids is involved in the activation of the human heme oxygenase-1 gene by UVA. Irradiation of human skin fibroblasts in the presence of the lipophilic antioxidants, butylated hydroxytoluene and alpha-tocopherol, enhances the UVA-induced HO-1 mRNA accumulation, suggesting that peroxidation of plasma membrane lipids is not involved. Furthermore, sodium ascorbate, which induces lipid peroxidation mainly in the plasma membrane, induces HO-1 mRNA to low levels only. The decrease in GSH by UVA radiation is not affected by the presence of the lipophilic antioxidants while ascorbate treatment increases the intracellular GSH by twofold above controls. These results indicate that peroxidation of internal membrane lipids, a decrease in the intracellular GSH levels and the integrity of the plasma membrane are all important for the UVA-induction of heme oxygenase-1. Both nonenzymatic as well as enzymatic lipid peroxidation metabolites are inducers of heme oxygenase-1. The nonenzymatic lipid peroxidation product 4-hydroxynonenal induces heme oxygenase-1 mRNA up to 40-fold and the phospholipase metabolites diacylglycerol and arachidonic acid induce this mRNA by three-to sixfold above basal levels. We also demonstrate that the cyclooxygenase metabolites of arachidonic acid are important for the UVA-activation of the heme oxygenase-1 gene.

Aldehydes↗