Knockdown of PCBER1, a gene of neolignan biosynthesis, resulted in increased poplar growth.

MAIN CONCLUSION: Poplar trees displayed an increased plant height due to the transgenic knockdown of PCBER1, a gene of lignan biosynthesis. The wood composition was slightly altered in both overexpression and knockdown lines. The gene PHENYLCOUMARAN BENZYLIC ETHER REDUCTASE1 (PCBER1) is well known as an important gene in the synthesis of lignans, a group of diverse phenylpropanoid derivatives. They are widely distributed in the plant kingdom and may have a role in both plant defense and growth regulation. To analyze its role in biomass formation and wood composition in poplar, both overexpression and knockdown approaches have been performed. Transgenic lines were analyzed on genetic and phenotypic levels, and partly in regard to their biomass composition. While the PCBER1 overexpression approach remained unremarkable concerning the plant height, biomass composition of obtained transgenic lines was modified. They had a significantly increased amount of ethanol extractives. The PCBER1 knockdown resulted in significantly deviating plants; after 17 months of greenhouse cultivation, transgenic plants were up to 38% higher compared to non-transgenic wild type. Most examined transgenic lines did not reveal a significantly enhanced stem diameter after three vegetation periods in the greenhouse. Significant changes were not obtained with regard to the three major wood components, lignin, cellulose and hemicelluloses. As a slight but not significant reduction in ethanol extractives was detected, the hypothesis arises that the lignan content could be influenced. Lignans become important in the pharmaceutical industry and clinical studies concerning cancer and other diseases, thus further investigations on lignan formation in poplar and its connection to biomass formation seem promising.

Influence of Regioselectively Sulfated Cellulose on in Vitro Vascularization of Biomimetic Bone Matrices.

Vascularization is essential for the regeneration of bone tissue within composite material. We measured the effect of regioselectively modified cellulose/hemicellulose as an additive for porous scaffolds of collagen/hydroxyapatite nanocomposite on the tubule formation of human vascular endothelial cells. Using a coculture of endothelial cells and fibroblasts, endothelial cells formed a network of tubules within an incubation time of 14 to 24 days. A cellulose sulfate with irregular sulfation pattern along the polysaccharide backbone (13-TACS-01) led to an additional increase in vascular endothelial growth factor (VEGF)-induced tubule formation, as observed in an in vitro angiogenesis assays. In contrast with structurally different heparin, these cellulose sulfates have no apparent affinity to VEGF. Their impact on endothelial function may possibly be due to interactions with cell surface receptors/soluble factors not yet defined.

Preparation and Characterization of Water-Soluble Xylan Ethers.

Xylan is a predominant hemicellulose component that is found in plants and in some algae. This polysaccharide is made from units of xylose (a pentose sugar). One promising source of xylan is oat spelt. This feedstock was used for the synthesis of two xylan ethers. To achieve water soluble products, we prepared dihydroxypropyl xylan as a non-ionic ether on the one hand, and carboxymethyl xylan as an ionic derivative on the other hand. Different preparation methods like heterogeneous, pseudo-homogeneous, and homogeneous syntheses were compared. In the case of dihydroxypropyl xylan, the synthesis method did not significantly affect the degree of substitution (DS). In contrast, in the case of carboxymethyl xylan, clear differences of the DS values were found in dependence on the synthesis method. Xylan ethers with DS values of >1 could be obtained, which mostly show good water solubility. The synthesized ionic, as well as non-ionic, xylan ethers were soluble in water, even though the aqueous solutions showed slight turbidity. Nevertheless, stable, transparent, and stainable films could be prepared from aqueous solutions from carboxymethyl xylans.

Synthesis and characterization of novel cellulose ether sulfates.

The synthesis and characterization of novel cellulose sulfate derivatives was reported. Various cellulose ethers were prepared in a homogeneous reaction with common sulfating agents. The received product possess different properties in dependence on the reaction conditions like sulfating agent, solvent, reaction time and reaction temperature. The cellulose ether sulfates are all soluble in water, they rheological behavior could be determined by viscosity measurements and the determination of the sulfur content by elemental analysis lead to a resulting degree of substitution ascribed to sulfate groups (DSSul) of the product. A wide range of products from DSSul 0.1 to DSSul 2.7 will be obtained. Furthermore the cellulose sulfate ethers could be characterized by Raman spectroscopy.

Encapsulated cells to focus the metabolic activation of anticancer drugs.

One of the first strategies for cancer gene therapy was the use of suicide gene/prodrug combinations, originally delivered to tumor cells using viral vectors. A major limitation of this approach was the inefficiency of suicide gene delivery. An alternative strategy, in which the suicide genes are physically juxtaposed to the tumor, involves the implantation of encapsulated, genetically modified cells. Cell encapsulation technologies were originally developed for the treatment of acquired and genetic diseases, such as diabetes. In the application of this technology for the treatment of tumors, cells that are genetically modified to overexpress suicide genes are encapsulated and implanted near solid tumors; this process is then followed by systemic prodrug administration. This review discusses the various cells types, suicide genes and prodrugs that have been used in preclinical and clinical trials, as well as the data that have been obtained from these studies. Future improvements for the production of second-generation approaches are also discussed.